Newsletter of the Animal Navigation Group
Issue No. 28 Autumn 2013
Contents
Navigational Efficiency of Nocturnal ‘Myrmecia’ Ants Suffers at Low Light Levels 5 Spatial memory and stereotypy of flight paths by big brown bats in cluttered surroundings 5 Bumblebee calligraphy: the design and control of flight motifs in the learning and return flights of Bombus terrestris 6 Coordinating compass-based and nest-based flight directions during bumblebee learning and return flights 6 Spontaneous magnetic orientation in larval Drosophila shares properties with learned magnetic compass responses in adult flies and mice 7 Magnetic Compass Orientation in the European Eel 7 Animal Behaviour: Monarchs Catch a Cold 8 Endogenous control of migratory behavior in Alaskan Northern Wheatears Oenanthe oenanthe 8 An unknown migration route of the "globally threatened" Aquatic Warbler revealed by geolocators 8 Migration strategies of the Yelkouan Shearwater Puffinus yelkouan 8 Orientation of shorebirds in relation to wind: both drift and compensation in the same region 9 Individual migratory patterns of two threatened seabirds revealed using stable isotope and geolocation analyses 9 Homeward bound: factors affecting homing ability in a polymorphic lizard 10 Migration confers survival benefits against avian predators for partially migratory freshwater fish 10 Pairs of pigeons act as behavioural units during route learning and co-navigational leadership conflicts 11 Response of a free-flying songbird to an experimental shift of the light polarization pattern around sunset 11 Back home at night or out until morning? Nycthemeral variations in homing of anosmic Cory's shearwaters in a diurnal colony 12 The invisible cues that guide king penguin chicks home: use of magnetic and acoustic cues during orientation and short-range navigation 12 Reception and learning of electric fields in bees 13 The behavioural ecology of animal movement: reflections upon potential synergies 13 In search of magnetosensitivity and ferromagnetic particles in Rhodnius prolixus: Behavioral studies and vibrating sample magnetometry 14 Orientation of migrating leatherback turtles in relation to ocean currents 14 Long-Distance Animal Migrations in the Oceanic Environment: Orientation and Navigation
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Correlates 15 Detection and Learning of Floral Electric Fields by Bumblebees 15 Interactions between the visual and the magnetoreception system: Different effects of bichromatic light regimes on the directional behavior of migratory birds 15 An experimental displacement and over 50 years of tag-recoveries show that monarch butterflies are not true navigators 16 Beware the Boojum: caveats and strengths of avian radar 16 Common orientation and layering of migrating insects in southeastern Australia observed with a Doppler weather radar 17 Passive Acoustic Tracking of Singing Humpback Whales (Megaptera novaeangliae) on a Northwest Atlantic Feeding Ground 17 Flexible weighing of olfactory and vector information in the desert ant Cataglyphis fortis 18 Visual Scene Perception in Navigating Wood Ants 18 Mechanistic models of animal migration behaviour – their diversity, structure and use 18 Sensory Navigation Device for Blind People 19 Repeat Tracking of Individual Songbirds Reveals Consistent Migration Timing but Flexibility in Route 19 Migration phenology and seasonal fidelity of an Arctic marine predator in relation to sea ice dynamics 20 Overshadowing of geometry learning by discrete landmarks in the water maze: Effects of relative salience and relative validity of competing cues 20 Predictive ethoinformatics reveals the complex migratory behaviour of a pelagic seabird, the Manx Shearwater 21 Migratory connectivity magnifies the consequences of habitat loss from sea-level rise for shorebird populations 21 Three-Phase Fuel Deposition in a Long-Distance Migrant, the Red Knot Calidris canutus piersmai, before the Flight to High Arctic Breeding Ground 22 Bird Migration Advances More Strongly in Urban Environments 22 Visual Navigation during Colony Emigration by the Ant Temnothorax rugatulus 22 Representation of Three-Dimensional Space in the Hippocampus of Flying Bats 23 A 3D Analysis of Flight Behavior of Malaria Mosquitoes in Response to Human Odor and Heat 23 A Distinct Layer of the Medulla Integrates Sky Compass Signals in the Brain of an Insect 24 The depth of the honeybee's backup sun-compass systems 24 Differences in Speed and Duration of Bird Migration between Spring and Autumn 25 Activity-dependent gene expression in honey bee mushroom bodies in response to orientation flight 25 Migrating Mule Deer: Effects of Anthropogenically Altered Landscapes 25 Error Properties of Argos Satellite Telemetry Locations Using Least Squares and Kalman Filtering 26 Ocean-finding in marine turtles: the importance of low-horizon elevation as an orientation cue 26 From random walks to informed movement 27 Homing Pigeons Respond to Time-Compensated Solar Cues Even in Sight of the Loft 28 An Iron-Rich Organelle in the Cuticular Plate of Avian Hair Cells 28 A magnetic pulse does not affect homing pigeon navigation: a GPS tracking experiment 28 Forty years of olfactory navigation in birds 29 Hippocampal Time Cells: Time versus Path Integration 29 Avian magnetic compass can be tuned to anomalously low magnetic intensities 30 A Trans-Hemispheric Migratory Songbird Does Not Advance Spring Schedules or Increase
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Migration Rate in Response to Record-Setting Temperatures at Breeding Sites 30 Passive electroreception in aquatic mammals 31 Are harbour seals (Phoca vitulina) able to perceive and use polarised light? 31 Edible Crabs "Go West": Migrations and Incubation Cycle of Cancer pagurus Revealed by Electronic Tags 31 Echolocation in Blainville's beaked whales (Mesoplodon densirostris) 32 Conditional Use of Social and Private Information Guides House-Hunting Ants 32 Increasing the Usability of Pedestrian Navigation Interfaces by means of Landmark Visibility Analysis 33 Biomimetic and bio-inspired robotics in electric fish research 33 Differential Regulation of Adipokines May Influence Migratory Behavior in the White- Throated Sparrow (Zonotrichia albicollis) 33 Rejoinder: challenge and opportunity in the study of ungulate migration amid environmental change 34 Environmental change and the evolution of migration 34 Animal migration amid shifting patterns of phenology and predation: lessons from a Yellowstone elk herd 35 Carry-over effects from breeding modulate the annual cycle of a long-distance migrant: an experimental demonstration 35 Sun Compass Orientation Helps Coral Reef Fish Larvae Return to Their Natal Reef 36 Advances in tracking small migratory birds: a technical review of light-level geolocation 36 The significance of midsummer movements of Autographa gamma: Implications for a mechanistic understanding of orientation behavior in a migrant moth 37 Apparent dissociation of photoperiodic time measurement between vernal migration and breeding under dim green light conditions in Gambel's white-crowned sparrow Zonotrichia leucophrys gambelii 37 Revealing the control of migratory fueling: An integrated approach combining laboratory and field studies in northern wheatears Oenanthe oenanthe 38 Lipid reserves and immune defense in healthy and diseased migrating monarchs Danaus plexippus 38 Premigratory fat metabolism in hummingbirds: A rumsfeldian approach 39 Development of the navigational system in homing pigeons: increase in complexity of the navigational map 39 Mapping the navigational knowledge of individually foraging ants, Myrmecia croslandi 39 Use of a light-dependent magnetic compass for y-axis orientation in European common frog (Rana temporaria) tadpoles 40 Automated long-term tracking and social behavioural phenotyping of animal colonies within a semi-natural environment 40 Projected climate-driven faunal movement routes 41 Movements and dispersal of farmed Atlantic salmon following a simulated-escape event 41 Site fidelity and homing behaviour in intertidal fishes 41 Satellite telemetry reveals behavioural plasticity in a green turtle population nesting in Sri Lanka 42 Context-dependent diel behavior of upstream-migrating anadromous fishes 42 Migration and dispersal patterns of bats and their influence on genetic structure. Bats are important ecosystems service providers, make a significant contribution to biodiversity and can be important pests and disease vectors. In spite of this, information on their migration and dispersal patterns is limited. 42 Fall movements of Red-headed Woodpeckers in South Carolina. 43 Effect of neck collars on the body condition of migrating Greater Snow Geese 43
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Migratory Reed Warblers Need Intact Trigeminal Nerves to Correct for a 1,000 km Eastward Displacement 44 Perceiving space and optical cues via a visuo-tactile sensory substitution system: a methodological approach for training of blind subjects for navigation 44 Complementary Roles of the Hippocampus and the Dorsomedial Striatum during Spatial and Sequence-Based Navigation Behavior 45 Annual rhythms that underlie phenology: biological time-keeping meets environmental change 45 Patterns and influences on Dolly Varden migratory timing in the Chignik Lakes, Alaska, and comparison of populations throughout the northeastern Pacific and Arctic oceans 46 Blue whales respond to simulated mid-frequency military sonar 46 Rates of straying by hatchery-produced Pacific salmon (Oncorhynchus spp.) and steelhead (Oncorhynchus mykiss) differ among species, life history types, and populations 47 A Depth-Based Head-Mounted Visual Display to Aid Navigation in Partially Sighted Individuals 47 High Altitude Bird Migration at Temperate Latitudes: A Synoptic Perspective on Wind Assistance 48 The homing frog: High homing performance in a territorial Dendrobatid frog Allobates femoralis (Dendrobatidae) 48 Oceanic navigation in Cory's shearwaters: evidence for a crucial role of olfactory cues for homing after displacement 48 Ocean navigation: smelling your way home 49 Directional compass preference for landing in water birds 49 Ant foraging and geodesic paths in labyrinths: Analytical and computational results 50 Selection pressures give composite correlated random walks Lévy walk characteristics 50 Exploring juvenile golden eagles' dispersal movements at two different temporal scales 50 Seasonal differences in behavior patterns of the migratory white-throated sparrow 51 High-altitude migration of Heteroptera in Britain 51 Flying at No Mechanical Energy Cost: Disclosing the Secret of Wandering Albatrosses 52 Scouts behave as streakers in honeybee swarms 52 Air speeds of migrating birds observed by ornithodolite and compared with predictions from flight theory 52 Travelling light: white sharks (Carcharodon carcharias) rely on body lipid stores to power ocean-basin scale migration 53 Are Lévy flight patterns derived from the Weber-Fechner law in distance estimation? 53 The Head-Direction Signal Is Critical for Navigation Requiring a Cognitive Map but Not for Learning a Spatial Habit 54 Pectoral fins aid in navigation of a complex environment by bluegill sunfish under sensory deprivation conditions 54 Ontogenetic development of magnetic compass orientation in domestic chickens (Gallus gallus) 54 Group recruitment in a thermophilic desert ant, Ocymyrmex robustior 55 Intra- and inter-individual variation in flight direction in a migratory butterfly co-vary with individual mobility 55 Learning of Multi-Modal Stimuli in Hawkmoths 56 Assignment tests, telemetry and tag-recapture data converge to identify natal origins of leatherback turtles foraging in Atlantic Canadian waters 57 Timing of songbird migration: individual consistency within and between seasons 57 Satellite telemetry reveals long-distance migration in the Asian great bustard Otis tarda dybowski 58
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Tracking multi-generational colonization of the breeding grounds by monarch butterflies in eastern North America 58 Do naive juvenile seabirds forage differently from adults? 59 Do sandhoppers use the skylight polarization as a compass cue? 59 Direct recordings of grid-like neuronal activity in human spatial navigation 60 Mapping Global Diversity Patterns for Migratory Birds 60 Comparative analysis of olfactory learning of Apis cerana and Apis mellifera 60 A radical sense of direction: signalling and mechanism in cryptochrome magnetoreception 61 Predicting the distribution of oceanic-stage Kemp's ridley sea turtles 61
No attempt has been made to standardize spelling in this Newsletter. Hence the reader will note the use of both English and American spelling, the determining factor being the spelling used in the original paper. It is hoped that this will not detract from the content of each abstract/summary. Similarly, no attempt has been made to Aimprove@ the syntax used in the original paper or to change the case of words in each title.
Navigational Efficiency of Nocturnal ‘Myrmecia’ Ants Suffers at Low Light Levels Insects face the challenge of navigating to specific goals in both bright sun-lit and dim-lit environments. Both diurnal and nocturnal insects use quite similar navigation strategies. This is despite the signal-to-noise ratio of the navigational cues being poor at low light conditions. To better understand the evolution of nocturnal life, we investigated the navigational efficiency of a nocturnal ant, 'Myrmecia pyriformis', at different light levels. Workers of M. pyriformis leave the nest individually in a narrow light-window in the evening twilight to forage on nest-specific 'Eucalyptus' trees. The majority of foragers return to the nest in the morning twilight, while few attempt to return to the nest throughout the night. We found that as light levels dropped, ants paused for longer, walked more slowly, the success in finding the nest reduced and their paths became less straight. We found that in both bright and dark conditions ants relied predominantly on visual landmark information for navigation and that landmark guidance became less reliable at low light conditions. It is perhaps due to the poor navigational efficiency at low light levels that the majority of foragers restrict navigational tasks to the twilight periods, where sufficient navigational information is still available. Narendra, A., Reid, S. F. & Raderschall, C. 2013. PLoS ONE 8, e58801. doi:10.1371/journal.pone.0058801
Spatial memory and stereotypy of flight paths by big brown bats in cluttered surroundings The big brown bat, Eptesicus fuscus, uses echolocation for foraging and orientation. The limited operating range of biosonar implies that bats must rely upon spatial memory in familiar spaces with dimensions larger than a few meters. Prior experiments with bats flying in obstacle arrays have revealed differences in flight and acoustic emission patterns depending on the density and spatial extent of the obstacles. Using the same method, combined with acoustic microphone array tracking, we flew big brown bats in an obstacle array that varied in density and distribution in different locations in the flight room. In the initial experiment, six bats learned individually stereotyped flight patterns as they became familiar with the space. After the first day, the repetition rate of sonar broadcasts dropped to a stable level, consistent with low-density clutter. In a second experiment, after acquiring
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their stable paths, each bat was released from each of two unfamiliar locations in the room. Each bat still followed the same flight path it learned originally. In a third experiment, performed 1 month after the first two experiments, three of the bats were re-flown in the same configuration of obstacles; these three resumed flying in their accustomed path. The other three bats were flown in a mirror-image reconfiguration of the obstacles; these bats quickly found stable flight paths that differed from their originally learned paths. Overall, the flight patterns indicate that the bats perceive the cluttered space as a single scene through which they develop globally organized flight paths Barchi, J. R., Knowles, J. M., Simmons, J. A. 2013. The Journal of Experimental Biology. 216, 1053-1063. doi: 10.1242/jeb.073197
Bumblebee calligraphy: the design and control of flight motifs in the learning and return flights of Bombus terrestris Many wasps and bees learn the position of their nest relative to nearby visual features during elaborate ‘learning’ flights that they perform on leaving the nest. Return flights to the nest are thought to be patterned so that insects can reach their nest by matching their current view to views of their surroundings stored during learning flights. To understand how ground-nesting bumblebees might implement such a matching process, we have video- recorded the bees' learning and return flights and analysed the similarities and differences between the principal motifs of their flights. Loops that take bees away from and bring them back towards the nest are common during learning flights and less so in return flights. Zigzags are more prominent on return flights. Both motifs tend to be nest based. Bees often both fly towards and face the nest in the middle of loops and at the turns of zigzags. Before and after flight direction and body orientation are aligned, the two diverge from each other so that the nest is held within the bees' fronto-lateral visual field while flight direction relative to the nest can fluctuate more widely. These and other parallels between loops and zigzags suggest that they are stable variations of an underlying pattern, which enable bees to store and reacquire similar nest-focused views during learning and return flights Philippides, A., de Ibarra, N. H., Riabinina, O., Collett, T. S. 2013. The Journal of Experimental Biology. 216, 1093-1104 doi:10.1242/jeb.081455
Coordinating compass-based and nest-based flight directions during bumblebee learning and return flights Bumblebees tend to face their nest over a limited range of compass directions when learning the nest's location on departure and finding it on their approach after foraging. They thus obtain similar views of the nest and its surroundings on their learning and return flights. How do bees coordinate their flights relative to nest-based and compass-based reference frames to get such similar views? We show, first, that learning and return flights contain straight segments that are directed along particular compass bearings, which are independent of the orientation of a bee's body. Bees are thus free within limits to adjust their viewing direction relative to the nest, without disturbing flight direction. Second, we examine the coordination of nest-based and compass-based control during likely information gathering segments of these flights: loops during learning flights and zigzags on return flights. We find that bees tend to start a loop or zigzag when flying within a restricted range of compass directions and to fly towards the nest and face it after a fixed change in compass direction, without continuous interactions between their nest-based and compass-based directions of flight. A preferred trajectory of compass-based flight over the course of a motif, combined with the tendency of the bees to keep their body oriented towards the
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nest automatically narrows the range of compass directions over which bees view the nest. Additionally, the absence of interactions between the two reference frames allows loops and zigzags to have a stereotyped form that can generate informative visual feedback Collett, T. S., de Ibarra, N. H., Riabinina, O., Philippides, A. 2013. The Journal of Experimental Biology. 216, 1105-1113. doi:10.1242/jeb.081463
Spontaneous magnetic orientation in larval Drosophila shares properties with learned magnetic compass responses in adult flies and mice We provide evidence for spontaneous quadramodal magnetic orientation in a larval insect. Second instar Berlin, Canton-S and Oregon-R × Canton-S strains of Drosophila melanogaster exhibited quadramodal orientation with clusters of bearings along the four anti-cardinal compass directions (i.e. 45, 135, 225 and 315 deg). In double-blind experiments, Canton-S Drosophila larvae also exhibited quadramodal orientation in the presence of an earth- strength magnetic field, while this response was abolished when the horizontal component of the magnetic field was cancelled, indicating that the quadramodal behavior is dependent on magnetic cues, and that the spontaneous alignment response may reflect properties of the underlying magnetoreception mechanism. In addition, a re-analysis of data from studies of learned magnetic compass orientation by adult Drosophila melanogaster and C57BL/6 mice revealed patterns of response similar to those exhibited by larval flies, suggesting that a common magnetoreception mechanism may underlie these behaviors. Therefore, characterizing the mechanism(s) of magnetoreception in flies may hold the key to understanding the magnetic sense in a wide array of terrestrial organisms Painter, M. S., Dommer, D. H., Altizer, W. W., Muheim, R. & Phillips, J. B. 2013. The Journal of Experimental Biology 216, 1307-1316. doi:10.1242/jeb.077404
Magnetic Compass Orientation in the European Eel European eel migrate from freshwater or coastal habitats throughout Europe to their spawning grounds in the Sargasso Sea. However, their route (~ 6000 km) and orientation mechanisms are unknown. Several attempts have been made to prove the existence of magnetoreception in Anguilla sp., but none of these studies have demonstrated magnetic compass orientation in earth-strength magnetic field intensities. We tested eels in four altered magnetic field conditions where magnetic North was set at geographic North, South, East, or West. Eels oriented in a manner that was related to the tank in which they were housed before the test. At lower temperature (under 12°C), their orientation relative to magnetic North corresponded to the direction of their displacement from the holding tank. At higher temperatures (12–17°C), eels showed bimodal orientation along an axis perpendicular to the axis of their displacement. These temperature-related shifts in orientation may be linked to the changes in behavior that occur between the warm season (during which eels are foraging) and the colder fall and winter (during which eels undertake their migrations). These observations support the conclusion that 1. Eels have a magnetic compass, and 2. They use this sense to orient in a direction that they have registered moments before they are displaced. The adaptive advantage of having a magnetic compass and learning the direction in which they have been displaced becomes clear when set in the context of the eel’s seaward migration. For example, if their migration is halted or blocked, as it is the case when environmental conditions become unfavorable or when they encounter a barrier, eels would be able to resume their movements along their old bearing when conditions become favorable again or when they pass by the barrier Durif, C. M. F., Browman, H. I., Phillips, J. B., Skiftesvik, A. B., Vøllestad, L. A. r. & Stockhausen, H. H. 2013. PLoS ONE 8, e59212. doi:10.1371/journal.pone.0059212
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Animal Behaviour: Monarchs Catch a Cold The spectacular migration of the Monarch from northeastern America to its overwintering grounds in Mexico requires the butterfly to set its time-compensated compass south in the autumn, then north in the spring foráits return home. The stimulus responsible for compass resetting has been identified as a reduction in temperature Kyriacou, C. 18-3-2013 Current Biology 23, R235-R236. doi: 10.1016/j.cub.2013.02.025
Endogenous control of migratory behavior in Alaskan Northern Wheatears Oenanthe oenanthe We tested endogenous migratory fuelling and nocturnal migratory restlessness in juvenile Northern Wheatears (Oenanthe oenanthe) from Alaska kept in captivity indoors. The birds showed a spontaneous seasonal, and biologically relevant, pattern of body mass development and nocturnal migratory restlessness. These data were compared to similar data of Northern Wheatears from Iceland. The Alaskan birds showed much higher restlessness but lower fuelling, which is consistent with their much longer journey but different ecological encounters Bulte, M., Bairlein, F. 2013. J Ornithol. 154, 567-570. doi:10.1007/s10336-012-0920-5
An unknown migration route of the "globally threatened" Aquatic Warbler revealed by geolocators The globally-threatened Aquatic Warbler (Acrocephalus paludicola) breeds in Europe and spends the northern winter in sub-Saharan West Africa. We attached 30 geolocators to breeding birds in the central Ukraine in 2010. Three geolocators which collected data from the autumn migration were recovered in 2011. They revealed apreviously-unknown migration route via southern Europe to stopover sites in south-western France and Spain. In West Africa, one bird spent some time well south of known non-breeding areas. For the conservation of some Aquatic Warbler populations, protection of hitherto unknown stopover sites in southern Europe and Africa may be crucial Salewski, V., Flade, M., Poluda, A., Kiljan, G., Liechti, F., Lisovski, S., Hahn, S. 2013 J Ornithol. 154, 549-552. doi: 10.1007/s10336-012-0912-5
Migration strategies of the Yelkouan Shearwater Puffinus yelkouan Although the Yelkouan Shearwater Puffinus yelkouan is listed as near threatened on the International Union for Conservation of Nature Red List, with many populations in serious decline, there is little detailed information on the location of its key foraging areas during the non-breeding season. To address this knowledge gap, adult Yelkouan Shearwaters at a breeding colony in Malta were fitted with geolocators in 2 consecutive years. Of the 13 birds tracked (two of which were tracked in both years), the majority (n = 10; 76.9 %) migrated in June-July to spend most of the non-breeding period in the Black Sea (n = 5), Aegean Sea (n = 2), Black and Aegean seas (n = 2), or Black and Adriatic seas (n = 1). The final three birds remained within the central Mediterranean area and did not move beyond 500 km of the breeding colony. There was considerable variation among individuals in terms of timing of the outward and return migrations, duration and location of periods of residency in different areas, and migration routes. However, migration patterns (including routes and areas visited) were very consistent in the two individuals tracked in consecutive years. All birds returned in November or December to waters closer to the breeding colony, concentrating between the North African coast and the southern Adriatic. This study has identified key areas during the non-breeding season for Yelkouan Shearwaters from Malta which are also likely to be important for other populations. Given the continuing
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decline of this species throughout its range, this information represents an essential step for improving international conservation efforts. At-sea threats in the wintering regions include by-catch in long-line and trawl fisheries, impacts of over-fishing, illegal hunting (particularly in Maltese waters), ingestion of plastics, pollution, and the potential impact of off-shore wind farms. These threats need to be addressed urgently in the areas identified by this study to prevent further declines Raine, A., Borg, J., Raine, H., Phillips, R. 2013. J Ornithol. 154, 411-422 doi: 10.1007/s10336-012-0905-4
Orientation of shorebirds in relation to wind: both drift and compensation in the same region Migratory movements in air or water are strongly affected by wind and ocean currents and an animal which does not compensate for lateral flow will be drifted from its intended direction of movement. We investigated whether arctic shorebirds during autumn migration in the region of South Sweden and the southern Baltic Sea compensate for wind drift or allow themselves to be drifted when approaching a known goal area under different circumstances (over sea, over land, at low and high altitude) using two different approaches, visual telescope observations and tracking radar. The shorebirds showed clearly different responses to crosswinds along this short section (<200 km) of the migratory journey, from almost full drift when departing over the sea, followed by partial drift and almost full compensation at higher altitudes over land during later stages. Our study demonstrates that shorebirds are also remarkably variable in their response to crosswinds during short sections of their migratory journey. The recorded initial drift close to departure is probably not adaptive but rather a result of constraints in the capacity of the birds to compensate in some situations, e.g. in low-altitude climbing flight over the sea. We found no difference in orientation response to wind between adult and juvenile birds. This study indicates, in addition to adaptive orientation responses to wind, the importance of the non-adaptive wind drift that contributes to increasing the variability of drift/compensation behaviour between places that are separated by only short distances, depending on the local topographic and environmental conditions Grönroos, J., Green, M., Alerstam, T. 2013. J Ornithol. 154, 385-392 doi: 10.1007/s10336-012-0902-7
Individual migratory patterns of two threatened seabirds revealed using stable isotope and geolocation analyses Aim Intraspecific variability in the migratory movements of seabirds is being revealed far more complex than hitherto recognized, and our lack of understanding undermines their effective protection. Our aim is to test whether the isotopic values of a single feather of two threatened seabirds, the Mediterranean (Puffinus yelkouan) and the Balearic (Puffinus mauretanicus) shearwaters allow the geographic assignment of birds to their non-breeding areas. Location These two species are known to use three main non-breeding areas: the NE Atlantic Ocean, the W Mediterranean and the Aegean-Black seas. Methods We clustered in three groups the δ13C and δ15N values of the first primary feather (P1), inferred to be grown during the non-breeding period, of 34 Mediterranean and 56 Balearic shearwaters accidentally caught by longliners. To link the isotopic values of P1 to its
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corresponding non-breeding area, we performed a discriminant function analysis (DFA) based on the three clusters and applied this function to feathers of known origin: P1 from seven Mediterranean shearwaters from Hyères Archipelago (France) tracked with geolocators and body feathers from six chicks from Balearic shearwaters. To link the moulting patterns to the areas where the feathers were grown, we applied the DFA to a sequence of primary feathers of eight Balearic and five Mediterranean shearwaters (caught by longliners). Results Isotopic and tracking data indicate that none of the Mediterranean shearwaters migrated to the Atlantic. The cluster and discriminant function analyses revealed that 8% of Balearic and 54% of Mediterranean shearwater moulted P1 in the Mediterranean Sea. Migratory movements were reflected in the changing isotopic values of the primary sequences. Main conclusions Stable isotope analyses (SIA) are a powerful approach to reveal the intraspecific variability in the migratory patterns of seabirds that use distinct isotopic areas over their annual cycle. The assignment of birds to their non-breeding areas by means of SIA is a simple and effective tool that can help to evaluate the impact of human activities in remote areas not only at population but also at individual level, which is an essential knowledge for the management and conservation of threatened species. Militão, T., Bourgeois, K., Roscales, J. L. and González-Solís, J. 2013. Diversity and Distributions. 19, 317–329. doi: 10.1111/j.1472-4642.2012.00916.x
Homeward bound: factors affecting homing ability in a polymorphic lizard Colour polymorphism is a widespread phenomenon among reptiles and is often associated with alternative physiological and behavioural strategies, including dispersal and movement patterns. To test the homing ability of Podarcis muralis and look for morph-specific responses, we conducted a translocation experiment in two areas of Northern Italy during 2009 and 2010. The first study area was a wall surrounding a city park with a linear and simplified habitat structure; the second one was an archaeological park in a natural area, including stone walls remains, grasses and woods. Lizards of both sexes (203 and 288 for site, respectively) were translocated at 50–200 m distances using cloth bags to block lizard sight. Podarcis muralis were able to return home as 56.7% of translocated individuals in the first site and 35.1% of translocated individuals in the second site successfully returned to their home range. The homing ability decreased with increasing distances, whereas body size positively affected homing behaviour, probably depending on the territoriality of adult lizards. More interestingly, homing performance differed among colour morphs, as yellow lizards of both sexes had significantly better homing skill than other morphs Scali, S., Sacchi, R., Azzusi, M., Daverio, S., Oppedisano, T. and Mangiacotti, M. 2013. Journal of Zoology. 289, 196–203. doi: 10.1111/j.1469-7998.2012.00977.x.
Migration confers survival benefits against avian predators for partially migratory freshwater fish The importance of predation risk in shaping patterns of animal migration is not well studied, mostly owing to difficulties in accurately quantifying predation risk for migratory versus resident individuals. Here, we present data from an extensive field study, which shows that migration in a freshwater fish (roach, Rutilus rutilus) that commonly migrates from lakes to streams during winter confers a significant survival benefit with respect to bird (cormorant, Phalacrocorax carbo spp.) predation. We tagged over 2000 individual fish in two Scandinavian lakes over 4 years and monitored migratory behaviour using passive telemetry.
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Next, we calculated the predation vulnerability of fish with differing migration strategies, by recovering data from passive integrated transponder tags of fish eaten by cormorants at communal roosts close to the lakes. We show that fish can reduce their predation risk from cormorants by migrating into streams, and that probability of being preyed upon by cormorants is positively related to the time individuals spend in the lake during winter. Our data add to the growing body of evidence that highlights the importance of predation for migratory dynamics, and, to our knowledge, is one of the first studies to directly quantify a predator avoidance benefit to migrants in the field Skov, C., Chapman, B. B., Baktoft, H., Brodersen, J., Brönmark, C., Hansson, L.- A., Hulthén, K. & Nilsson, P. A. 2013. Biology Letters 9, doi: 10.1098/rsbl.2012.1178
Pairs of pigeons act as behavioural units during route learning and co- navigational leadership conflicts In many species, group members obtain benefits from moving collectively, such as enhanced foraging efficiency or increased predator detection. In situations where the group's decision involves integrating individual preferences, group cohesion can lead to more accurate outcomes than solitary decisions. In homing pigeons, a classic model in avian orientation studies, individuals learn habitual routes home, but whether and how co-navigating birds acquire and share route-based information is unknown. Using miniature GPS loggers, we examined these questions by first training pairs (the smallest possible flocks) of pigeons together, and then releasing them with other pairs that had received separate pair-training. Our results show that, much like solitary individuals, pairs of birds are able to establish idiosyncratic routes that they recapitulate together faithfully. Also, when homing with other pairs they exhibit a transition from a compromise- to a leadership-like mechanism of conflict resolution as a function of the degree of disagreement (distance separating the two preferred routes) between the two pairs, although pairs tolerate a greater range of disagreements prior to the transition than do single birds. We conclude that through shared experiences during past decision-making, pairs of individuals can become units so closely coordinated that their behaviour resembles that of single birds. This has implications for the behaviour of larger groups, within which certain individuals have closer social affiliations or share a history of previous associations Flack, A., Freeman, R., Guilford, T., Biro, D. 2013. The Journal of Experimental Biology. 216, 1434-1438 doi: 10.1016/j.anbehav.2011.12.018
Response of a free-flying songbird to an experimental shift of the light polarization pattern around sunset The magnetic field, the sun, the stars and the polarization pattern of visible light during twilight are important cues for orientation in nocturnally migrating songbirds. As these cues change with time and location on Earth, the polarization pattern was put forward as a likely key reference system calibrating the other compass systems. Whether this applies generally to migratory birds is, however, controversially discussed. We used an experimental approach in free-flying birds to study the role of polarization for their departure direction in autumn. Experimental birds experienced a 90 deg shift of the band of maximum polarization during sunset, whereas control birds experienced the polarization pattern as under natural conditions. Full view of the sunset cues near the horizon was provided during the cue conflict exposure. Here we show that both the experimental and the control birds being released after nautical twilight departed consistently towards south-southeast. Radiotelemetry allowed tracking of the first 15 km of the birds' outward journey, thus the intrinsic migration direction as chosen by the birds was measured. We found no
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recalibration of the magnetic compass after pre-exposure to a cue conflict between the natural magnetic field and the artificially shifted polarization pattern at sunset. The lacking difference in the departure direction of both groups may suggest that birds did not recalibrate any of the compass systems during the experiment. As free-flying migrants can use all available orientation cues after release, it remains unknown whether our birds might have used the magnetic and/or star compass to determine their departure direction Schmaljohann, H., Rautenberg, T., Muheim, R., Naef-Daenzer, B., Bairlein, F. 2013 The Journal of Experimental Biology. 216, 1381-1387. doi: 10.1242/jeb.080580
Back home at night or out until morning? Nycthemeral variations in homing of anosmic Cory's shearwaters in a diurnal colony Olfactory cues have been shown to be important to homing petrels at night, but apparently those procellariiform species that also come back to the colony during the day are not impaired by smell deprivation. However, the nycthemeral distribution of homing, i.e. whether displaced birds released at night return to their burrow by night or during daylight, has never been investigated. To explore this question, we studied the homing behaviour of Cory's shearwater (Calonectris borealis) in the only known population where these birds are active at the colony both during the day and at night. Here, we compared the nocturnal versus diurnal homing schedule of birds treated with zinc sulphate (to induce a reversible but complete anosmia) with that of controls. Our results show that anosmic shearwaters were unable to home in the dark and were constrained to wait for the daylight to find their burrow again. Our results confirm that olfaction is the basic sensory input for homing by night even in a petrel species that is diurnally active at the colony Dell'Ariccia, G., Bonadonna, F. 2013. The Journal of Experimental Biology. 216, 1430-1433 doi: 10.1242/jeb.082826
The invisible cues that guide king penguin chicks home: use of magnetic and acoustic cues during orientation and short-range navigation King penguins (Aptenodytes patagonicus) live in large and densely populated colonies, where navigation can be challenging because of the presence of many conspecifics that could obstruct locally available cues. Our previous experiments demonstrated that visual cues were important but not essential for king penguin chicks' homing. The main objective of this study was to investigate the importance of non-visual cues, such as magnetic and acoustic cues, for chicks' orientation and short-range navigation. In a series of experiments, the chicks were individually displaced from the colony to an experimental arena where they were released under different conditions. In the magnetic experiments, a strong magnet was attached to the chicks' heads. Trials were conducted in daylight and at night to test the relative importance of visual and magnetic cues. Our results showed that when the geomagnetic field around the chicks was modified, their orientation in the arena and the overall ability to home was not affected. In a low sound experiment we limited the acoustic cues available to the chicks by putting ear pads over their ears, and in a loud sound experiment we provided additional acoustic cues by broadcasting colony sounds on the opposite side of the arena to the real colony. In the low sound experiment, the behavior of the chicks was not affected by the limited sound input. In the loud sound experiment, the chicks reacted strongly to the colony sound. These results suggest that king penguin chicks may use the sound of the colony while orienting towards their home. Nesterova, A. P., Chiffard, J., Couchoux, C., Bonadonna, F. 2013. The Journal of Experimental Biology. 216, 1491-1500 doi: 10.1242/jeb.075564
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Reception and learning of electric fields in bees Honeybees, like other insects, accumulate electric charge in flight, and when their body parts are moved or rubbed together. We report that bees emit constant and modulated electric fields when flying, landing, walking and during the waggle dance. The electric fields emitted by dancing bees consist of low- and high-frequency components. Both components induce passive antennal movements in stationary bees according to Coulomb's law. Bees learn both the constant and the modulated electric field components in the context of appetitive proboscis extension response conditioning. Using this paradigm, we identify mechanoreceptors in both joints of the antennae as sensors. Other mechanoreceptors on the bee body are potentially involved but are less sensitive. Using laser vibrometry, we show that the electrically charged flagellum is moved by constant and modulated electric fields and more strongly so if sound and electric fields interact. Recordings from axons of the Johnston organ document its sensitivity to electric field stimuli. Our analyses identify electric fields emanating from the surface charge of bees as stimuli for mechanoreceptors, and as biologically relevant stimuli, which may play a role in social communication Greggers, U., Koch, G., Schmidt, V., Dürr, A., Floriou-Servou, A., Piepenbrock, D., Göpfert, M. C., Menzel, R. 2013 Proceedings of the Royal Society B: Biological Sciences. 280 doi:10.1098/rspb.2013.0528
The behavioural ecology of animal movement: reflections upon potential synergies Animal movement acts at multiple scales: it can shape the destiny of individuals and populations, govern community and ecosystem structure, and influence evolutionary processes and patterns of biodiversity. Recent technological advances, such as the revolutionary developments in tracking technology and remote sensing, provide fresh insights and the possibility to collect detailed data on where and how animals travel through space, how they react to and/or interact with their environment and conspecifics as well as their predators and prey. Scientists from various disciplines ranging from physics to psychology develop and apply ever improving analytical techniques to observe, assess and archive animal movement across scales. As in any other field, standardising data collection is a key prerequisite in order to combine and extend dataset collections, many of which may further be utilized by behavioural ecologists to answer questions on the function and significance of animal movements. Large-scale manipulative experimental approaches have also shed new light on old questions in animal movement, and opened new and previously inaccessible perspectives to study animal movement in the context of behavioural ecology. Animal movements are intrinsic to all behavioural processes, and analysis of movement phenomena within the framework of behavioural ecology has provided rich insights into the mechanisms and functions of animal behavior for some decades. We convened an international symposium to reflect on the behavioural ecology of animal movement, asking how these two related disciplines can produce new insights and synergies. Our symposium provided a platform that brought together a diverse range of researchers working on animal movement on different taxa and a range of spatial scales to discuss how behavioural ecology can integrate with the nascent discipline of movement ecology. In this short paper we summarise the key points from this meeting, and call for a renewed focus on the behavioural processes involved in the movements of animals Liedvogel, M., Chapman, B. B., Muheim, R., Akesson, S. 2013 Animal Migration, 1, 39-46 doi: 10.2478/ami-2013-0002
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In search of magnetosensitivity and ferromagnetic particles in Rhodnius prolixus: Behavioral studies and vibrating sample magnetometry Magnetoreception is a sensory mechanism with wide phylogenetic distribution, which many organisms use for navigation and orientation. Radical pair reactions and the use of magnetic particles have been proposed as mechanisms for magnetosensitivity in terrestrial animals. Magnetosensitivity and the presence of a ferromagnetic material were tested in the hematophagous bug Rhodnius prolixus (Hemiptera: Reduviidae: Triatominae) vector of Chagas disease in Colombia and Venezuela. R. prolixus is well known in both countries for its active dispersal that allows flow of individuals from sylvatic to domestic environments. Behavioral experiments quantifying the number of body rotations and quadrant changes in a Petri dish were carried out, applying 1 mT artificial field in a constant direction for 45 min and rotated 180° every 5 min for 45 min. In addition, magnetite presence in the abdomens of Apis mellifera (positive control) and the bodies of R. prolixus was tested using a vibrating sample magnetometer (VSM). No differences in the number of body rotations and quadrant changes were found in R. prolixus with and without the presence of an artificial magnetic field. Results obtained with the VSM indicate presence of ferromagnetic material (hysteresis loop) in A. mellifera abdomens and absence of ferromagnetic material in R. prolixus bodies. Both VSM and behavioral results suggest that magnetosensitivity by a ferromagnetic hypothesis is not present in R. prolixus. Finally, our results indicate that the VSM magnetometer is a sensitive technique for detecting ferromagnetic material in insect tissues Giraldo, D., Hernández, C. & Molina, J. 2013. Journal of Insect Physiology 59, 345-350 doi:10.1016/j.jinsphys.2012.12.005
Orientation of migrating leatherback turtles in relation to ocean currents During their offshore movements, leatherback turtles, Dermochelys coriacea, associate frequently with ocean currents and mesoscale oceanographic features such as eddies, and their movements are often in accordance with the current flow. To investigate how individual turtles oriented their ground- and water-related movements in relation to the currents encountered on their journeys, we used oceanographic techniques to estimate the direction and intensity of ocean currents along the course of 15 leatherbacks tracked by satellite during their long-distance movements in the Indian and Atlantic Oceans. For all individuals a non-negligible component of active swimming was evident throughout the journeys, even when their routes closely followed the currents, but overall the turtle water- related orientation was random with respect to current directions. For turtles in the North Atlantic, the ground-related movements largely derived from the turtles' active swimming, while in the Indian Ocean currents contributed substantially to the observed movements. The same pattern was shown when distinct parts of the routes corresponding to foraging bouts and travelling segments were considered separately. These findings substantiate previous qualitative observations of leatherback movements, by revealing that turtles were not simply drifting passively but rather swam actively during most of their journeys, although with a random orientation with respect to currents. Our analysis did not provide any indication that leatherbacks were able to detect the current drift they were exposed to, further highlighting the navigational challenges they face in their oceanic wanderings Galli, S., Gaspar, P., Fossette, S., Calmettes, B., Hays, G. C., Lutjeharms, J. R. E. & Luschi, P. 2012. Animal Behaviour 84, 1491-1500 doi:10.1016/j.anbehav.2012.09.022
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Long-Distance Animal Migrations in the Oceanic Environment: Orientation and Navigation Correlates A large variety of marine animals migrate in the oceanic environment, sometimes aiming at specific targets such as oceanic islands or offshore productive areas. Thanks to recent technological developments, various techniques are available to track marine migrants, even when they move in remote or inhospitable areas. The paper reviews the main findings obtained by tracking marine animals during migratory travels extending over large distances, with a special attention to the orientation and navigation aspects of these phenomena. Long- distance movements have now been recorded in many marine vertebrates, revealing astonishing performances such as individual fidelity to specific sites and basin-wide movements directed towards these locations. Seabirds cover the longest distances, sometimes undertaking interhemispheric flights, but transoceanic migrations are also the rule in pelagic fish, turtles, pinnipeds, and whales. Some features of these journeys call for the involvement of efficient orientation and navigational abilities, but little evidence is available in this respect. Oceanic migrants most likely rely on biological compasses to maintain a direction in the open sea, and displacement experiments have provided evidence for an ability of seabirds and turtles to rely on position-fixing mechanisms, possibly involving magnetic and/or olfactory cues, although simpler navigational systems are not to be excluded Luschi, P. 2013 ISRN Zoology Article ID 631839 doi:10.1155/2013/631839
Detection and Learning of Floral Electric Fields by Bumblebees Insects use several senses to forage, detecting floral cues such as color, shape, pattern, and volatiles. We report a formerly unappreciated sensory modality in bumblebees (Bombus terrestris) detection of floral electric fields. These fields act as floral cues, which are affected by the visit of naturally charged bees. Like visual cues, floral electric fields exhibit variations in pattern and structure, which can be discriminated by bumblebees. We also show that such electric field information contributes to the complex array of floral cues that together improve a pollinator’s memory of floral rewards. Because floral electric fields can change within seconds, this sensory modality may facilitate rapid and dynamic communication between flowers and their pollinators Clarke, D., Whitney, H., Sutton, G. & Robert, D. 2013. Science 340, 66-69 doi: 10.1126/science.1230883
Interactions between the visual and the magnetoreception system: Different effects of bichromatic light regimes on the directional behavior of migratory birds When magnetic compass orientation of migratory robins was tested, the birds proved well oriented under low intensity monochromatic light of shorter wavelengths up to 565 nm green; from 583 nm yellow onward, they were disoriented. In the present study, we tested robins under bichromatic lights composed (1) of 424 nm blue and 565 nm green and (2) of 565 nm green and 583 nm yellow at two intensities. Under dim blue–green light with a total quantal flux of ca. 8 x 1015 quanta/ s m2, the birds were well oriented in their migratory direction by their inclination compass; under blue–green light of twice this intensity, their orientation became axial. In both cases, the magnetic directional information was mediated by the radical pair processes in the eye. When green and yellow light were combined, however, the nature of the behavior changed. Under green–yellow light of the higher intensity, the birds showed a ‘fixed direction’ response that was polar, no longer controlled by the normal inclination compass; under dim green–yellow light, the response became axial.
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Under these two light conditions, the respective directional information was mediated by the magnetite-based receptors in the skin of the upper beak. Apparently, yellow light leads to a change from one magnetoreception system to the other. How this change is effected is still unknown; it appears to reflect complex interactions between the visual and the two magnetoreception systems Wiltschko, R., Dehe, L., Gehring, D., Thalau, P. & Wiltschko, W. 2013. Journal of Physiology-Paris 107, 137-146. doi:10.1016/j.jphysparis.2012.03.003
An experimental displacement and over 50 years of tag-recoveries show that monarch butterflies are not true navigators Monarch butterflies (Danaus plexippus) breeding in eastern North America are famous for their annual fall migration to their overwintering grounds in Mexico. However, the mechanisms they use to successfully reach these sites remain poorly understood. Here, we test whether monarchs are true navigators who can determine their location relative to their final destination using both a "compass" and a "map". Using flight simulators, we recorded the orientation of wild-caught monarchs in southwestern Ontario and found that individuals generally flew in a southwest direction toward the wintering grounds. When displaced 2,500 km to the west, the same individuals continued to fly in a general southwest direction, suggesting that monarchs use a simple vector-navigation strategy (i.e., use a specific compass bearing without compensating for displacement). Using over 5 decades of field data, we also show that the directional concentration and the angular SD of recoveries from tagged monarchs largely conformed to two mathematical models describing the directional distribution of migrants expected under a vector-navigation strategy. A third analysis of tagged recoveries shows that the increasing directionality of migration from north to south is largely because of the presence of geographic barriers that guide individuals toward overwintering sites. Our work suggests that monarchs breeding in eastern North America likely combine simple orientation mechanisms with geographic features that funnel them toward Mexican overwintering sites, a remarkable achievement considering that these butterflies weigh less than a gram and travel thousands of kilometers to a site they have never seen Mouritsen, H., Derbyshire, R., Stalleicken, J., Mouritsen, O. Ø., Frost, B. J., Norris, D. R. 2013. Proceedings of the National Academy of Sciences. online early. doi: 10.1073/pnas.1221701110
Beware the Boojum: caveats and strengths of avian radar Radar provides a useful and powerful tool to wildlife biologists and ornithologists. However, radar also has the potential for errors on a scale not previously possible. In this paper, we focus on the strengths and limitations of avian surveillance radars that use marine radar front-ends integrated with digital radar processors to provide 360° of coverage. Modern digital radar processors automatically extract target information, including such various target attributes as location, speed, heading, intensity, and radar cross-section (size) as functions of time. Such data can be stored indefinitely, providing a rich resource for ornithologists and wildlife managers. Interpreting these attributes in view of the sensor’s characteristics from which they are generated is the key to correctly deriving and exploiting application-specific information about birds and bats. We also discuss (1) weather radars and air-traffic control surveillance radars that could be used to monitor birds on larger, coarser spatial scales; (2) other nonsurveillance radar configurations, such as vertically scanning radars used for vertical profiling of birds along a particular corridor; and (3)
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Doppler, single-target tracking radars used for extracting radial velocity and wing-beat frequency information from individual birds for species identification purposes. Beason, R. C. Nohara, T. J. Weber, P. 2013. Human–Wildlife Interactions 7 16–46
Common orientation and layering of migrating insects in southeastern Australia observed with a Doppler weather radar Australia's migratory insects, including the Australian Plague Locust (Chortoicetes terminifera Walker), were observed with Doppler weather radar during the Austral spring and summer of 2010–2011. On occasion, the presence of a dumbbell pattern in the reflectivity indicated insects taking a common orientation. Using the radial velocity, the average orientation and direction of travel of the insects were determined. Common orientation was most clearly observed shortly before or after dawn, and occasionally in the evening. However, signs of orientation were observed in different migrant populations throughout the day. The cases selected for this study described a daily cycle of migration phases and associated atmospheric conditions. The weather was characterized using surface observations, analysis charts and numerical weather prediction model fields. Migrating insects were profuse during convective weather. Insects often aggregated into layers, particularly in the vicinity of the nocturnal inversion. Copyright © 2013 Royal Meteorological Society Rennie, S. J. 2013 . Meteorological Applications, doi: 10.1002/met.1378
Passive Acoustic Tracking of Singing Humpback Whales (Megaptera novaeangliae) on a Northwest Atlantic Feeding Ground Passive acoustic tracking provides an unobtrusive method of studying the movement of sound-producing animals in the marine environment where traditional tracking methods may be costly or infeasible. We used passive acoustic tracking to characterize the fine-scale movements of singing humpback whales (Megaptera novaeangliae) on a northwest Atlantic feeding ground. Male humpback whales produce complex songs, a phenomenon that is well documented in tropical regions during the winter breeding season, but also occurs at higher latitudes during other times of year. Acoustic recordings were made throughout 2009 using an array of autonomous recording units deployed in the Stellwagen Bank National Marine Sanctuary. Song was recorded during spring and fall, and individual singing whales were localized and tracked throughout the array using a correlation sum estimation method on the time-synchronized recordings. Tracks were constructed for forty-three song sessions, revealing a high level of variation in movement patterns in both the spring and fall seasons, ranging from slow meandering to faster directional movement. Tracks were 30 min to 8 h in duration, and singers traveled distances ranging from 0.9 to 20.1 km. Mean swimming speed was 2.06 km/h (SD 0.95). Patterns and rates of movement indicated that most singers were actively swimming. In one case, two singers were tracked simultaneously, revealing a potential acoustic interaction. Our results provide a first description of the movements of singers on a northwest Atlantic feeding ground, and demonstrate the utility of passive acoustic tracking for studying the fine-scale movements of cetaceans within the behavioral context of their calls. These methods have further applications for conservation and management purposes, particularly by enhancing our ability to estimate cetacean densities using passive acoustic monitoring Stanistreet, J. E., Risch, D. & Van Parijs, S. M. 2013. PLoS ONE 8, e61263. doi:10.1371/journal.pone.0061263
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Flexible weighing of olfactory and vector information in the desert ant Cataglyphis fortis Desert ants, Cataglyphis fortis, are equipped with remarkable skills that enable them to navigate efficiently. When travelling between the nest and a previously visited feeding site, they perform path integration (PI), but pinpoint the nest or feeder by following odour plumes. Homing ants respond to nest plumes only when the path integrator indicates that they are near home. This is crucial, as homing ants often pass through plumes emanating from foreign nests and do not discriminate between the plume of their own and that of a foreign nest, but should absolutely avoid entering a wrong nest. Their behaviour towards food odours differs greatly. Here, we show that in ants on the way to food, olfactory information outweighs PI information. Although PI guides ants back to a learned feeder, the ants respond to food odours independently of whether or not they are close to the learned feeding site. This ability is beneficial, as new food sources-unlike foreign nests-never pose a threat but enable ants to shorten distances travelled while foraging. While it has been shown that navigating C. fortis ants rely strongly on PI, we report here that the ants retained the necessary flexibility in the use of PI Buehlmann, C., Hansson, B. S., Knaden, M. 2013. Biology Letters. 9, doi: 10.1098/rsbl.2013.0070
Visual Scene Perception in Navigating Wood Ants Ants, like honeybees, can set their travel direction along foraging routes using just the surrounding visual panorama . This ability gives us a way to explore how visual scenes are perceived. By training wood ants to follow a path in an artificial scene and then examining their path within transformed scenes, we identify several perceptual operations that contribute to the ants' choice of direction. The first is a novel extension to the known ability of insects to compute the "center of mass" of large shapes: ants learn a desired heading toward a point on a distant shape as the proportion of the shape that lies to the left and right of the aiming point-the 'fractional position of mass' (FPM). The second operation, the extraction of local visual features like oriented edges, is familiar from studies of shape perception . Ants may use such features for guidance by keeping them in desired retinal locations. Third, ants exhibit segmentation. They compute the learned FPM over the whole of a simple scene, but over a segmented region of a complex scene. We suggest how the three operations may combine to provide efficient directional guidance Lent, D., Graham, P., Collett, T. 2013. Current Biology. online early doi: 10.1016/j.cub.2013.03.016
Mechanistic models of animal migration behaviour – their diversity, structure and use Migration is a widespread phenomenon in the animal kingdom, including many taxonomic groups and modes of locomotion. Developing an understanding of the proximate and ultimate causes for this behaviour not only addresses fundamental ecological questions but has relevance to many other fields, for example in relation to the spread of emerging zoonotic diseases, the proliferation of invasive species, aeronautical safety as well as the conservation of migrants. * Theoretical methods can make important contributions to our understanding of migration, by allowing us to integrate findings on this complex behaviour, identify caveats in our understanding and to guide future empirical research efforts. Various mechanistic models exist to date, but their applications seem to be scattered and far from evenly distributed across taxonomic units. Therefore, we provide an overview of the major mechanistic modelling approaches used in the study of migration behaviour and characterize
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their fundamental features, assumptions and limitations and discuss their typical data requirements both for model parameterization and for scrutinizing model predictions. Furthermore, we review 155 studies that have used mechanistic models to study animal migration and analyse them with regard to the approaches used and the focal species, and also explore their contribution to advancing current knowledge within six broad migration ecology research themes. This identifies important gaps in our present knowledge, which should be tackled in future research using existing and to-be developed theoretical approaches Bauer, S. & Klaassen, M. 2013. Journal of Animal Ecology 82, 498-508 doi: 10.1111/1365-2656.12054
Sensory Navigation Device for Blind People This paper presents a new Electronic Travel Aid (ETA) ‘Acoustic Prototype’ which is especially suited to facilitate the navigation of visually impaired users. The device consists of a set of 3-Dimensional Complementary Metal Oxide Semiconductor (3-D CMOS) image sensors based on the three-dimensional integration and Complementary Metal-Oxide Semiconductor (CMOS) processing techniques implemented into a pair of glasses, stereo headphones as well as a Field-Programmable Gate Array (FPGA) used as processing unit. The device is intended to be used as a complementary device to navigation through both open known and unknown environments. The FPGA and the 3D-CMOS image sensor electronics control object detection. Distance measurement is achieved by using chip- integrated technology based on the Multiple Short Time Integration method. The processed information of the object distance is presented to the user via acoustic sounds through stereophonic headphones. The user interprets the information as an acoustic image of the surrounding environment. The Acoustic Prototype transforms the surface of the objects of the real environment into acoustical sounds. The method used is similar to a bat's acoustic orientation. Having good hearing ability, with few weeks training the users are able to perceive not only the presence of an object but also the object form (that is, if the object is round, if it has corners, if it is a car or a box, if it is a cardboard object or if it is an iron or cement object, a tree, a person, a static or moving object). The information is continuously delivered to the user in a few nanoseconds until the device is shut down, helping the end user to perceive the information in real time. Dunai, L., Peris-Fajarnés, G., Lluna, E. & Defez, B. 2013. The Journal of Navigation 66, 349-362. doi: 10.1017/S0373463312000574
Repeat Tracking of Individual Songbirds Reveals Consistent Migration Timing but Flexibility in Route Tracking repeat migratory journeys of individual animals is required to assess phenotypic plasticity of individual migration behaviour in space and time. We used light-level geolocators to track the long-distance journeys of migratory songbirds (wood thrush,
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phenotypic plasticity in timing of spring migration, which may limit the ability of individuals to adjust migration schedules in response to climate change Stanley, C. Q., MacPherson, M., Fraser, K. C., McKinnon, E. A. & Stutchbury, B. J. M. 2013. PLoS ONE 7, e40688. doi:10.1371/journal.pone.0040688
Migration phenology and seasonal fidelity of an Arctic marine predator in relation to sea ice dynamics Understanding how seasonal environmental conditions affect the timing and distribution of synchronized animal movement patterns is a central issue in animal ecology. * Migration, a behavioural adaptation to seasonal environmental fluctuations, is a fundamental part of the life history of numerous species. However, global climate change can alter the spatiotemporal distribution of resources and thus affect the seasonal movement patterns of migratory animals. * We examined sea ice dynamics relative to migration patterns and seasonal geographical fidelity of an Arctic marine predator, the polar bear (Ursus maritimus). Polar bear movement patterns were quantified using satellite-linked telemetry data collected from collars deployed between 1991–1997 and 2004–2009. * We showed that specific sea ice characteristics can predict the timing of seasonal polar bear migration on and off terrestrial refugia. In addition, fidelity to specific onshore regions during the ice- free period was predicted by the spatial pattern of sea ice break-up but not by the timing of break-up. The timing of migration showed a trend towards earlier arrival of polar bears on shore and later departure from land, which has been driven by climate-induced declines in the availability of sea ice. * Changes to the timing of migration have resulted in polar bears spending progressively longer periods of time on land without access to sea ice and their marine mammal prey. The links between increased atmospheric temperatures, sea ice dynamics, and the migratory behaviour of an ice-dependent species emphasizes the importance of quantifying and monitoring relationships between migratory wildlife and environmental cues that may be altered by climate change Cherry, S. G., Derocher, A. E., Thiemann, G. W. & Lunn, N. J. 2013. Journal of Animal Ecology Early view. doi: 10.1111/1365-2656.12050.
Overshadowing of geometry learning by discrete landmarks in the water maze: Effects of relative salience and relative validity of competing cues The effects of stimulus salience and cue validity in the overshadowing of geometric features of an enclosed arena by discrete landmarks were investigated in rats using the water maze paradigm. Experiment 1 established that in a rhomboid-shaped arena, the acute corner was more salient than the obtuse corner. In Experiment 2, rats were trained to find a submerged platform either in one of the acute, or obtuse, corners. In addition to the information provided by corner angle, the platform was also signaled by the presence of a spherical landmark suspended above the platform for rats in the experimental group. The landmark was a more valid cue for predicting the location of the platform than the angle of the corner. This training resulted in overshadowing of learning about the angle of the corner by the presence of the landmark. The final experiment extended this result by showing that when the predictive validities of the angle and the landmark were matched in the experimental group, learning about geometry was still overshadowed by the presence of landmarks, but only in animals that were trained with the platform at an obtuse, but not acute, corner. These results uniquely demonstrate that learning about geometry can be overshadowed by discrete landmarks, and also that whether overshadowing is observed
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depends on the stimulus salience and the relative validity of the competing cues. These findings imply that learning based on geometric cues follows the same basic rules that apply to a wide range of other learning paradigms Kosaki, Y., Austen, J. M., McGregor, A. 2013. Journal of Experimental Psychology: Animal Behavior Processes. 39, 126-139 doi:10.1037/a0031199
Predictive ethoinformatics reveals the complex migratory behaviour of a pelagic seabird, the Manx Shearwater Understanding the behaviour of animals in the wild is fundamental to conservation efforts. Advances in bio-logging technologies have offered insights into the behaviour of animals during foraging, migration and social interaction. However, broader application of these systems has been limited by device mass, cost and longevity. Here, we use information from multiple logger types to predict individual behaviour in a highly pelagic, migratory seabird, the Manx Shearwater (Puffinus puffinus). Using behavioural states resolved from GPS tracking of foraging during the breeding season, we demonstrate that individual behaviours can be accurately predicted during multi-year migrations from low cost, lightweight, salt-water immersion devices. This reveals a complex pattern of migratory stopovers: some involving high proportions of foraging, and others of rest behaviour. We use this technique to examine three consecutive years of global migrations, revealing the prominence of foraging behaviour during migration and the importance of highly productive waters during migratory stopover Freeman, R., Dean, B., Kirk, H., Leonard, K., Phillips, R. A., Perrins, C. M., Guilford, T. 2013 Journal of The Royal Society Interface. 10, online early doi: 10.1098/rsif.2013.0279
Migratory connectivity magnifies the consequences of habitat loss from sea-level rise for shorebird populations Sea-level rise (SLR) will greatly alter littoral ecosystems, causing habitat change and loss for coastal species. Habitat loss is widely used as a measurement of the risk of extinction, but because many coastal species are migratory, the impact of habitat loss will depend not only on its extent, but also on where it occurs. Here, we develop a novel graph-theoretic approach to measure the vulnerability of a migratory network to the impact of habitat loss from SLR based on population flow through the network. We show that reductions in population flow far exceed the proportion of habitat lost for 10 long-distance migrant shorebirds using the East Asian-Australasian Flyway. We estimate that SLR will inundate 23- 40% of intertidal habitat area along their migration routes, but cause a reduction in population flow of up to 72 per cent across the taxa. This magnifying effect was particularly strong for taxa whose migration routes contain bottlenecks-sites through which a large fraction of the population travels. We develop the bottleneck index, a new network metric that positively correlates with the predicted impacts of habitat loss on overall population flow. Our results indicate that migratory species are at greater risk than previously realized Iwamura, T., Possingham, H. P., Chades, Minton, C., Murray, N. J., Rogers, D. I., Treml, E. A., Fuller, R. A. 2013 Proceedings of the Royal Society B: Biological Sciences. 280, online early doi: 10.1098/rspb.2013.0325
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Three-Phase Fuel Deposition in a Long-Distance Migrant, the Red Knot Calidris canutus piersmai, before the Flight to High Arctic Breeding Ground Refuelling by migratory birds before take-off on long flights is generally considered a two- phase process, with protein accumulation preceding rapid fat deposition. The first phase expresses the demands for a large digestive system for nutrient storage after shrinkage during previous flights, the second phase the demands for fat stores to fuel the subsequent flight. At the last staging site in northward migration, this process may include expression of selection pressures both en route to and after arrival at the breeding grounds, which remains unascertained. Here we investigated changes in body composition during refuelling of High Arctic breeding red knots (Calidris canutus piersmai) in the northern Yellow Sea, before their flight to the tundra. These red knots followed a three-phase fuel deposition pattern, with protein being stored in the first and last phases, and fat being deposited mainly in the second phase. Thus, they did not shrink nutritional organs before take-off, and even showed hypertrophy of the nutritional organs. These suggest the build up of strategic protein stores before departure to cope with a protein shortage upon arrival on the breeding grounds. Further comparative studies are warranted to examine the degree to which the deposition of stores by migrant birds generally reflects a balance between concurrent and upcoming environmental selection pressures Hua, N., Piersma, T. & Ma, Z. 2013 s. PLoS ONE 8, e62551 doi:10.1371/journal.pone.0062551
Bird Migration Advances More Strongly in Urban Environments Urbanization has a marked effect on the reproduction and other ecological and behavioural traits of many living organisms, including birds. In migrant birds, survival and reproductive output is influenced by the (mis)synchronization of arrival with the availability of resources. Many recent studies have shown that arrival timing is related to temperatures en-route and at destination. Because urban areas are heat islands, with higher temperatures that influence earlier vegetation and invertebrate development, this should favour earlier arrival of migrant birds to cities rather than to rural areas. In this paper, we analysed differences between urban and rural habitats in mean dates and trends of first arrival dates of 18 species of migratory bird species in western Poland during 1983-2010. For many individual species, and overall, mean first arrival date was significantly earlier in rural areas than in urban areas (significant for 11 species). However, the trend towards earlier first arrival dates was stronger in urban areas for 15 of the 18 species (significantly stronger in four species). Consequently, arrival dates in urban areas are fast approaching, or have now matched or passed those in rural areas. These findings suggest that recent environmental changes may have more rapidly changed the migratory habits of birds occupying urban habitats than those occupying rural habitats Tryjanowski, P., Sparks, T. H., Kuźniak, S., Czechowski, P. & Jerzak, L. 2013 PLoS ONE 8, e63482. doi:10.1371/journal.pone.0063482
Visual Navigation during Colony Emigration by the Ant Temnothorax rugatulus Many ants rely on both visual cues and self-generated chemical signals for navigation, but their relative importance varies across species and context. We evaluated the roles of both modalities during colony emigration by Temnothorax rugatulus. Colonies were induced to move from an old nest in the center of an arena to a new nest at the arena edge. In the midst of the emigration the arena floor was rotated 60uaround the old nest entrance, thus displacing any substrate-bound odor cues while leaving visual cues unchanged. This
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manipulation had no effect on orientation, suggesting little influence of substrate cues on navigation. When this rotation was accompanied by the blocking of most visual cues, the ants became highly disoriented, suggesting that they did not fall back on substrate cues even when deprived of visual information. Finally, when the substrate was left in place but the visual surround was rotated, the ants’ subsequent headings were strongly rotated in the same direction, showing a clear role for visual navigation. Combined with earlier studies, these results suggest that chemical signals deposited by Temnothorax ants serve more for marking of familiar territory than for orientation. The ants instead navigate visually, showing the importance of this modality even for species with small eyes and coarse visual acuity Bowens, Sean R., Glatt, Daniel P., Pratt, 1., PLoS One doi:10.1371/journal.pone.0064367
Representation of Three-Dimensional Space in the Hippocampus of Flying Bats Many animals, on air, water, or land, navigate in three-dimensional (3D) environments, yet it remains unclear how brain circuits encode the animal's 3D position. We recorded single neurons in freely flying bats, using a wireless neural-telemetry system, and studied how hippocampal place cells encode 3D volumetric space during flight. Individual place cells were active in confined 3D volumes, and in >90% of the neurons, all three axes were encoded with similar resolution. The 3D place fields from different neurons spanned different locations and collectively represented uniformly the available space in the room. Theta rhythmicity was absent in the firing patterns of 3D place cells. These results suggest that the bat hippocampus represents 3D volumetric space by a uniform and nearly isotropic rate code Yartsev, M. M., & Ulanovsky, N., 2013. Science 340, 367-372. doi:10.1126/science 1235338
A 3D Analysis of Flight Behavior of Malaria Mosquitoes in Response to Human Odor and Heat Female mosquitoes use odor and heat as cues to navigate to a suitable landing site on their blood host. The way these cues affect flight behavior and modulate anemotactic responses, however, is poorly understood. We studied in-flight behavioral responses of females of the nocturnal malaria mosquito to human odor and heat. Flight-path characteristics in a wind tunnel (flow 20 cm/s) were quantified in three dimensions. With wind as the only stimulus (control), short and close to straight upwind flights were recorded. With heat alone, flights were similarly short and direct. The presence of human odor, in contrast, caused prolonged and highly convoluted flight patterns. The combination of odor+heat resulted in longer flights with more landings on the source than to either cue alone. Flight speed was greatest (mean groundspeed 27.2 cm/s) for odor+heat. Odor alone resulted in decreased flight speed when mosquitoes arrived within 30 cm of the source whereas mosquitoes exposed to odor+heat maintained a high flight speed while flying in the odor plume, until they arrived within 15 cm of the source. Human odor evoked an increase in crosswind flights with an additive effect of heat at close range (<15 cm) to the source. This was found for both horizontal and vertical flight components. However, mosquitoes nevertheless made upwind progress when flying in the odor+heat generated plume, suggesting that mosquitoes scan their environment intensively while they progress upwind towards their host. These observations may help to improve the efficacy of trapping systems for malaria mosquitoes by (1) optimizing the site of odor release relative to trap entry and (2) adding a heat source
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which enhances a landing response Spitzen, J., Spoor, C. W., Grieco, F., ter Braak, C., Beeuwkes, J., van Brugge, S. P., Kranenbarg, S., Noldus, L. P. J. J., van Leeuwen, J. L. & Takken, W. 2013 PLoS ONE 8, e62995. doi:10.1371/journal.pone.0062995
A Distinct Layer of the Medulla Integrates Sky Compass Signals in the Brain of an Insect Mass migration of desert locusts is a common phenomenon in North Africa and the Middle East but how these insects navigate is still poorly understood. Laboratory studies suggest that locusts are able to exploit the sky polarization pattern as a navigational cue. Like other insects locusts detect polarized light through a specialized dorsal rim area (DRA) of the eye. Polarization signals are transmitted through the optic lobe to the anterior optic tubercle (AOTu) and, finally, to the central complex in the brain. Whereas neurons of the AOTu integrate sky polarization and chromatic cues in a daytime dependent manner, the central complex holds a topographic representation of azimuthal directions suggesting a role as an internal sky compass. To understand further the integration of sky compass cues we studied polarization-sensitive (POL) neurons in the medulla that may be intercalated between DRA photoreceptors and AOTu neurons. Five types of POL-neuron were characterized and four of these in multiple recordings. All neurons had wide arborizations in medulla layer 4 and most, additionally, in the dorsal rim area of the medulla and in the accessory medulla, the presumed circadian clock. The neurons showed type-specific orientational tuning to zenithal polarized light and azimuth tuning to unpolarized green and UV light spots. In contrast to neurons of the AOTu, we found no evidence for color opponency and daytime dependent adjustment of sky compass signals. Therefore, medulla layer 4 is a distinct stage in the integration of sky compass signals that precedes the time-compensated integration of celestial cues in the AOTu el Jundi, B., Pfeiffer, K. & Homberg, U. 2013. PLoS ONE 6, e27855. doi:10.1371/journal.pone.0027855
The depth of the honeybee's backup sun-compass systems Honeybees have at least three compass mechanisms: a magnetic compass; a celestial or sun compass, based on the daily rotation of the sun and sun-linked skylight patterns; and a backup celestial compass based on a memory of the sun's movements over time in relation to the landscape. The interactions of these compass systems have yet to be fully elucidated, but the celestial compass is primary in most contexts, the magnetic compass is a backup in certain contexts, and the bees' memory of the sun's course in relation to the landscape is a backup system for cloudy days. Here we ask whether bees have any further compass systems, for example a memory of the sun's movements over time in relation to the magnetic field. To test this, we challenged bees to locate the sun when their known celestial compass systems were unavailable, that is, under overcast skies in unfamiliar landscapes. We measured the bees' knowledge of the sun's location by observing their waggle dances, by which foragers indicate the directions toward food sources in relation to the sun's compass bearing. We found that bees have no celestial compass systems beyond those already known: under overcast skies in unfamiliar landscapes, bees attempt to use their landscape- based backup system to locate the sun, matching the landscapes or skylines at the test sites with those at their natal sites as best they can, even if the matches are poor and yield weak or inconsistent orientation Dovey, K. M., Kemfort, J. R., Towne, W. F. 2013. The Journal of Experimental Biology. 216, 2129-2139. doi: 10.1242/jeb.084160
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Differences in Speed and Duration of Bird Migration between Spring and Autumn It has been suggested that birds migrate faster in spring than in autumn because of competition for arrival order at breeding grounds and environmental factors such as increased daylight. Investigating spring and autumn migration performances is important for understanding ecological and evolutionary constraints in the timing and speed of migration. We compiled measurements from tracking studies and found a consistent predominance of cases showing higher speeds and shorter durations during spring compared to autumn, in terms of flight speeds (airspeed, ground speed, daily travel speed), stopover duration, and total speed and duration of migration. Seasonal differences in flight speeds were generally smaller than those in stopover durations and total speed/duration of migration, indicating that rates of foraging and fuel deposition were more important than flight speed in accounting for differences in overall migration performance. Still, the seasonal differences in flight speeds provide important support for time selection in spring migration Nilsson, C., Raymond, H. G., Alerstam, T. 2013. The American Naturalist. 181, 837- 845. doi: 10.1086/670335
Activity-dependent gene expression in honey bee mushroom bodies in response to orientation flight The natural history of adult worker honey bees (Apis mellifera) provides an opportunity to study the molecular basis of learning in an ecological context. Foragers must learn to navigate between the hive and floral locations that may be up to miles away. Young pre- foragers prepare for this task by performing orientation flights near the hive, during which they begin to learn navigational cues such as the appearance of the hive, the position of landmarks, and the movement of the sun. Despite well-described spatial learning and navigation behavior, there is currently limited information on the neural basis of insect spatial learning. We found that Egr, an insect homolog of Egr-1, is rapidly and transiently upregulated in the mushroom bodies in response to orientation. This result is the first example of an Egr-1 homolog acting as a learning-related immediate-early gene in an insect and also demonstrates that honey bee orientation uses a molecular mechanism that is known to be involved in many other forms of learning. This transcriptional response occurred both in na+»ve bees and in foragers induced to re-orient. Further experiments suggest that visual environmental novelty, rather than exercise or memorization of specific visual cues, acts as the stimulus for Egr upregulation. Our results implicate the mushroom bodies in spatial learning and emphasize the deep conservation of Egr-related pathways in experience-dependent plasticity Lutz, C. C., Robinson, G. E. 2013. The Journal of Experimental Biology. 216, 2031-2038. doi: 10.1242/jeb.084905
Migrating Mule Deer: Effects of Anthropogenically Altered Landscapes Migration is an adaptive strategy that enables animals to enhance resource availability and reduce risk of predation at a broad geographic scale. Ungulate migrations generally occur along traditional routes, many of which have been disrupted by anthropogenic disturbances. Spring migration in ungulates is of particular importance for conservation planning, because it is closely coupled with timing of parturition. The degree to which oil and gas development affects migratory patterns, and whether ungulate migration is sufficiently plastic to compensate for such changes, warrants additional study to better understand this critical conservation issue. Methodology/Principal Findings We studied timing and synchrony of departure from
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winter range and arrival to summer range of female mule deer Odocoileus hemionus in northwestern Colorado, USA, which has one of the largest natural-gas reserves currently under development in North America. We hypothesized that in addition to local weather, plant phenology, and individual life-history characteristics, patterns of spring migration would be modified by disturbances associated with natural-gas extraction. We captured 205 adult female mule deer, equipped them with GPS collars, and observed patterns of spring migration during 2010. Conclusions/Significance. Timing of spring migration was related to winter weather (particularly snow depth) and access to emerging vegetation, which varied among years, but was highly synchronous across study areas within years. Additionally, timing of migration was influenced by the collective effects of anthropogenic disturbance, rate of travel, distance traveled, and body condition of adult females. Rates of travel were more rapid over shorter migration distances in areas of high natural-gas development resulting in the delayed departure, but early arrival for females migrating in areas with high development compared with less-developed areas. Such shifts in behavior could have consequences for timing of arrival on birthing areas, especially where mule deer migrate over longer distances or for greater durations Lendrum, P. E., Anderson, C. R., Jr., Monteith, K. L., Jenks, J. A. & Bowyer, R. T. 2013. PLoS ONE 8, e64548.
Error Properties of Argos Satellite Telemetry Locations Using Least Squares and Kalman Filtering Study of animal movements is key for understanding their ecology and facilitating their conservation. The Argos satellite system is a valuable tool for tracking species which move long distances, inhabit remote areas, and are otherwise difficult to track with traditional VHF telemetry and are not suitable for GPS systems. Previous research has raised doubts about the magnitude of position errors quoted by the satellite service provider CLS. In addition, no peer-reviewed publications have evaluated the usefulness of the CLS supplied error ellipses nor the accuracy of the new Kalman filtering (KF) processing method. Using transmitters hung from towers and trees in southeastern Peru, we show the Argos error ellipses generally contain ~25% of the true locations and therefore do not adequately describe the true location errors. We also find that KF processing does not significantly increase location accuracy. The errors for both LS and KF processing methods were found to be lognormally distributed, which has important repercussions for error calculation, statistical analysis, and data interpretation. In brief, ‘good’ positions (location codes 3, 2, 1, A) are accurate to about 2 km, while 0 and B locations are accurate to about 5–10 km. However, due to the lognormal distribution of the errors, larger outliers are to be expected in all location codes and need to be accounted for in the user data processing. We evaluate five different empirical error estimates and find that 68% lognormal error ellipses provided the most useful error estimates. Longitude errors are larger than latitude errors by a factor of 2 to 3, supporting the use of elliptical error ellipses. Numerous studies over the past 15 years have also found fault with the CLS-claimed error estimates yet CLS has failed to correct their misleading information. We hope this will be reversed in the near future Boyd, J. D. & Brightsmith, D. J. 2013. PLoS ONE 8, e63051 doi:10.1371/journal.pone.0063051
Ocean-finding in marine turtles: the importance of low-horizon elevation as an orientation cue Sea finding behaviour in hatchling sea turtles is widely believed to be guided by orientation
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towards the brightest horizon and away from high silhouettes. We propose that the horizon profile at the lowest angle of elevation is a more important cue for ocean finding than light intensity. Examples of hatchling orientation occurring at natural nest sites, at preselected beach release sites, and within a walled wooden arena under various conditions in the field, are presented. We conclude that hatchlings orient as follows: (1) Hatchlings move towards the horizon line at the lowest angle of elevation; (2) Hatchlings move away from high silhouettes, in a direction that remains close to the horizon line at the lowest angle of elevation; (3) Should a conflict exist regarding the direction of lowest horizon elevation, hatchlings move towards the brightest lowest horizon. This refinement to current theory explains numerous instances of natural non-ocean-finding behaviour in marine turtles, which occur both by day and by night, and in the absence of artificial lighting. We propose that the disruption caused to hatchling orientation by artificial lighting close to nesting beaches occurs because bright lights mask the horizon line as a cue by making it impossible to discern, causing the hatchlings to move towards the only visible "horizon" — the artificial lights. Consequently, we recommend that managers of sea turtle rookeries where turtles have an ocean-finding problem should manipulate the beach profile to ensure the direction of the ocean matches the lowest angle of elevation, in combination with light reduction strategies — as the most effective means of preventing disrupted orientation Limpus, C., Kamrowski, R. L. 2013. Brill. doi: 10.1163/1568539X-00003083
From random walks to informed movement The analysis of animal movement is a large and continuously growing field of research. Detailed knowledge about movement strategies is of crucial importance for understanding eco-evolutionary dynamics at all scales - from individuals to (meta-)populations. This and the availability of detailed movement and dispersal data motivated Nathan and colleagues to published their much appreciated call to base movement ecology on a more thorough mechanistic basis. So far, most movement models are based on random walks. However, even if a random walk might describe real movement patterns acceptably well, there is no reason to assume that animals move randomly. Therefore, mechanistic models of foraging strategies should be based on information use and memory in order to increase our understanding of the processes that lead to animal movement decisions. We present a mechanistic movement model of an animal with a limited perceptual range and basic information storage capacities. This 'spatially informed forager' constructs an internal map of its environment by using perception, memory and learned or evolutionarily acquired assumptions about landscape attributes. We analyse resulting movement patterns and search efficiencies and compare them to area restricted search strategies (ARS) and biased correlated random walks (BCRW) of omniscient individuals. We show that, in spite of their limited perceptual range, spatially informed individuals boost their foraging success and may perform much better than the best ARS. The construction of an internal map and the use of spatial information results in the emergence of a highly correlated walk between patches and a rather systematic search within resource clusters. Furthermore, the resulting movement patterns may include foray search behaviour. Our work highlights the strength of mechanistic modelling approaches and sets the stage for the development of more sophisticated models of memory use for movement decisions and dispersal Fronhofer, E. A., Hovestadt, T., Poethke, H. J. 2013. Oikos. 122, 857-866. doi: 10.1111/j.1600-0706.2012.21021.x
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Homing Pigeons Respond to Time-Compensated Solar Cues Even in Sight of the Loft The sun has long been thought to guide bird navigation as the second step in a two-stage process, in which determining position using a map is followed by course setting using a compass, both over unfamiliar and familiar terrain. The animal’s endogenous clock time- compensates the solar compass for the sun’s apparent movement throughout the day, and this allows predictable deflections in orientation to test for the compass’ influence using clock-shift manipulations. To examine the influence of the solar compass during a highly familiar navigational task, 24 clock-shifted homing pigeons were precision-tracked from a release site close to and in sight of their final goal, the colony loft. The resulting trajectories displayed significant partial deflection from the loft direction as predicted by either fast or slow clock-shift treatments. The partial deflection was also found to be stable along the entire trajectory indicating regular updating of orientation via input from the solar compass throughout the final approach flight to the loft. Our results demonstrate that time- compensated solar cues are deeply embedded in the way birds orient during homing flight, are accessed throughout the journey and on a remarkably fine-grained scale, and may be combined effectively simultaneously with direct guidance from familiar landmarks, even when birds are flying towards a directly visible goal Armstrong, C., Wilkinson, H., Meade, J., Biro, D., Freeman, R. & Guilford, T. 2013. PLoS ONE 8, e63130. doi:10.1371/journal.pone.0063130
An Iron-Rich Organelle in the Cuticular Plate of Avian Hair Cells Hair cells reside in specialized epithelia in the inner ear of vertebrates, mediating the detection of sound, motion, and gravity. The transduction of these stimuli into a neuronal impulse requires the deflection of stereocilia, which are stabilized by the actin-rich cuticular plate. Recent electrophysiological studies have implicated the vestibular system in pigeon magnetosensation [1]. Here we report the discovery of a single iron-rich organelle that resides in the cuticular plate of cochlear and vestibular hair cells in the pigeon. Transmission electron microscopy, coupled with elemental analysis, has shown that this structure is composed of ferritin-like granules, is approximately 300-600 nm in diameter, is spherical, and in some instances is membrane-bound and/or organized in a paracrystalline array. This organelle is found in hair cells in a wide variety of avian species, but not in rodents or in humans. This structure may function as (1) a store of excess iron, (2) a stabilizer of stereocilia, or (3) a mediator of magnetic detection. Given the specific subcellular location, elemental composition, and evolutionary conservation, we propose that this structure is an integral component of the sensory apparatus in birds Lauwers, M., Pichler, P., Edelman, N. B., Resch, G. P., Ushakova, L., Salzer, M. C., Heyers, D., Saunders, M., Shaw, J., and Keays, D. A. 20-5-2013 Current Biology 23, 924-929. doi:10.1016/j.cub.2013.04.025
A magnetic pulse does not affect homing pigeon navigation: a GPS tracking experiment The cues by which homing pigeons are able to return to a home loft after displacement to unfamiliar release sites remain debated. A number of experiments in which migratory birds have been treated with a magnetic pulse have produced a disruption in their orientation, which argues that a ferrimagnetic sense is used for navigation in birds. One previous experiment has also indicated an effect of magnetic pulses on homing pigeon navigation, although with inconsistent results. Previous studies have shown that some magnetic-related information is transmitted by the trigeminal nerve to the brain in some bird species,
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including the homing pigeon. The function of this information is still unclear. It has been suggested that this information is important for navigation. Previous studies with trigeminal nerve lesioned homing pigeons have clearly shown that the lack of trigeminally mediated information, even if magnetic, is not crucial for homing performance. However, this result does not completely exclude the possibility that other ferrimagnetic receptors in the homing pigeon play a role in navigation. Additionally, recent studies on homing pigeons suggested the existence of a ferrimagnetic sense in a novel location presumably located in the inner ear (lagena). In the present study, we tested whether any ferrimagnetic magnetoreceptors, irrespective of their location in the bird's head, are involved in pigeons' homing. To do this, we treated homing pigeons with a strong magnetic pulse before release, tracked birds with GPS loggers and analyzed whether this treatment affected homing performance. In the single previous magnetic pulse experiment on homing pigeons, only initial orientation at a release site was considered and the results were inconsistent. We observed no effect of the magnetic pulse at any of the sites used on initial orientation, homing performance, tortuosity or track efficiency, which does not support a role for the ferrimagnetic sense in homing pigeon navigation, at least not in this geographic area, where magnetic field variations are in the region of 200 nT intensity and 0.8 deg inclination. Holland, R., Filannino, C., Gagliardo, A. 2013. The Journal of Experimental Biology. 216, 2192-2200. doi: 10.1242/jeb.083543
Forty years of olfactory navigation in birds Forty years ago, Papi and colleagues discovered that anosmic pigeons cannot find their way home when released at unfamiliar locations. They explained this phenomenon by developing the olfactory navigation hypothesis: pigeons at the home loft learn the odours carried by the winds in association with wind direction; once at the release site, they determine the direction of displacement on the basis of the odours perceived locally and orient homeward. In addition to the old classical experiments, new GPS tracking data and observations on the activation of the olfactory system in displaced pigeons have provided further evidence for the specific role of olfactory cues in pigeon navigation. Although it is not known which odours the birds might rely on for navigation, it has been shown that volatile organic compounds in the atmosphere are distributed as fairly stable gradients to allow environmental odour-based navigation. The investigation of the potential role of olfactory cues for navigation in wild birds is still at an early stage; however, the evidence collected so far suggests that olfactory navigation might be a widespread mechanism in avian species Gagliardo, A. 2013. The Journal of Experimental Biology. 216, 2165-2171. doi: 10.1242/jeb.070250
Hippocampal Time Cells: Time versus Path Integration Recent studies have reported the existence of hippocampal time cells, neurons that fire at particular moments during periods when behavior and location are relatively constant. However, an alternative explanation of apparent time coding is that hippocampal neurons path integrate to encode the distance an animal has traveled. Here, we examined hippocampal neuronal firing patterns as rats ran in place on a treadmill, thus clamping behavior and location, while we varied the treadmill speed to distinguish time elapsed from distance traveled. Hippocampal neurons were strongly influenced by time and distance, and less so by minor variations in location. Furthermore, the activity of different neurons reflected integration over time and distance to varying extents, with most neurons strongly influenced by both factors and some significantly influenced by only time or distance. Thus, hippocampal neuronal networks captured both the organization of time and distance in a
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situation where these dimensions dominated an ongoing experience. "Hippocampal neurons fire in sequences during treadmill running" Hippocampal neuronal activity reflects location, time, and distance Kraus et al. report that, during stationary treadmill running, hippocampal neuronal activity reflects integration of both time elapsed and distance traveled, in addition other salient features of experience Kraus, Benjamin, Robinson, Robert, White, John, Eichenbaum, Howard, and Hasselmo, Michael. 23-5-2013 Neuron online early.
Avian magnetic compass can be tuned to anomalously low magnetic intensities The avian magnetic compass works in a fairly narrow functional window around the intensity of the local geomagnetic field, but adjusts to intensities outside this range when birds experience these new intensities for a certain time. In the past, the geomagnetic field has often been much weaker than at present. To find out whether birds can obtain directional information from a weak magnetic field, we studied spontaneous orientation preferences of migratory robins in a 4 µT field (i.e. a field of less than 10 per cent of the local intensity of 47 µT). Birds can adjust to this low intensity: they turned out to be disoriented under 4 µT after a pre-exposure time of 8 h to 4 µT, but were able to orient in this field after a total exposure time of 17 h. This demonstrates a considerable plasticity of the avian magnetic compass. Orientation in the 4 µT field was not affected by local anaesthesia of the upper beak, but was disrupted by a radiofrequency magnetic field of 1.315 MHz, 480 nT, suggesting that a radical-pair mechanism still provides the directional information in the low magnetic field. This is in agreement with the idea that the avian magnetic compass may have developed already in the Mesozoic in the common ancestor of modern birds Winklhofer, M., Dylda, E., Thalau, P., Wiltschko, W., Wiltschko, R. 2013. Proceedings of the Royal Society B: Biological Sciences. 280, doi: 10.1098/rspb.2013.0853.
A Trans-Hemispheric Migratory Songbird Does Not Advance Spring Schedules or Increase Migration Rate in Response to Record-Setting Temperatures at Breeding Sites The decline of long distance migratory songbirds has been linked to an increasing mismatch between spring arrival date and timing of food availability caused by climate change. It is unclear to what extent individuals can adjust migration timing or en route rate in response to annual variation in temperature at breeding sites. We tracked the ca. 7300 km spring migration of 52 purple martins Progne subis from the Amazon basin to two breeding sites in eastern North America. Spring 2012 was the warmest on record in eastern North America, but contrary to predictions, this did not result in earlier departure, faster migration, or earlier arrival at breeding areas compared with earlier years. Temperatures and rainfall in the Amazon basin at the time of departure were not higher in 2012, and conditions along migration routes did not give consistent signals of a warmer spring at the breeding site. Once in North America, individuals likely had limited opportunity to speed up their migration because this final portion of the journey was already very rapid (570 km/d; 4–5 d in duration). Migration timing over the entire journey was best predicted by breeding latitude and sex and was not sensitive to ecological cues (temperature and rainfall amount) at departure from South American overwintering sites or en route, in contrast to recent studies of other songbirds. Our results provide the first direct evidence for a mismatch between higher spring temperatures at breeding sites and departure schedules of individual songbirds, and suggest phenotypic responses to short-term climatic warming may be limited for some species. Further direct-tracking data with greater geographic and temporal scope
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is needed to test for individual plasticity in response to temperature and rainfall along migratory routes for this, and other, species Fraser, K. C., Silverio, C., Kramer, P., Mickle, N., Aeppli, R. & Stutchbury, B. J. M. 2013 PLoS ONE 8, e64587. doi:10.1371/journal.pone.0064587
Passive electroreception in aquatic mammals Passive electroreception is a sensory modality in many aquatic vertebrates, predominantly fishes. Using passive electroreception, the animal can detect and analyze electric fields in its environment. Most electric fields in the environment are of biogenic origin, often produced by prey items. These electric fields can be relatively strong and can be a highly valuable source of information for a predator, as underlined by the fact that electroreception has evolved multiple times independently. The only mammals that possess electroreception are the platypus (Ornithorhynchus anatinus) and the echidnas (Tachyglossidae) from the monotreme order, and, recently discovered, the Guiana dolphin (Sotalia guianensis) from the cetacean order. Here we review the morphology, function and origin of the electroreceptors in the two aquatic species, the platypus and the Guiana dolphin. The morphology shows certain similarities, also similar to ampullary electroreceptors in fishes, that provide cues for the search for electroreceptors in more vertebrate and invertebrate species. The function of these organs appears to be very similar. Both species search for prey animals in low-visibility conditions or while digging in the substrate, and sensory thresholds are within one order of magnitude. The electroreceptors in both species are innervated by the trigeminal nerve. The origin of the accessory structures, however, is completely different; electroreceptors in the platypus have developed from skin glands, in the Guiana dolphin, from the vibrissal system Czech-Damal, N. U., Dehnhardt, G., Manger, P., Hanke, W. 2013. J Comp Physiol A. 199, 555-563. doi: 10.1007/s00359-012-0780-8
Are harbour seals (Phoca vitulina) able to perceive and use polarised light? Harbour seals are active at night and during the day and see well in both air and water. Polarised light, which is a well-known visual cue for orientation, navigation and foraging, is richly available in harbour seal habitats, both above and below the water surface. We hypothesised that an ability to detect and use polarised light could be valuable for seals, and thus tested if they are able to see this property of light. We performed two behavioural experiments, one involving object discrimination and the other involving object detection. These objects were presented to the seals as two-dimensional stimuli on a specially modified liquid crystal display that generated objects whose contrast was purely defined in terms of polarisation (i.e. objects lacked luminance contrast). In both experiments, the seals' performance did not deviate significantly from chance. In contrast, the seals showed a high baseline performance when presented with objects on a non-modified display (whose contrast was purely defined in terms of luminance). We conclude that harbour seals are unable to use polarised light in our experimental context. It remains for future work to elucidate if they are polarisation insensitive per se Hanke, F. D., Miersch, L., Warrant, E. J., Mitschke, F. M., Dehnhardt, G. 2013 J Comp Physiol A. 199, 509-519. doi: 10.1007/s00359-012-0762-x
Edible Crabs "Go West": Migrations and Incubation Cycle of Cancer pagurus Revealed by Electronic Tags Crustaceans are key components of marine ecosystems which, like other exploited marine taxa, show seasonable patterns of distribution and activity, with consequences for their
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availability to capture by targeted fisheries. Despite concerns over the sustainability of crab fisheries worldwide, difficulties in observing crabs' behaviour over their annual cycles, and the timings and durations of reproduction, remain poorly understood. From the release of 128 mature female edible crabs tagged with electronic data storage tags (DSTs), we demonstrate predominantly westward migration in the English Channel. Eastern Channel crabs migrated further than western Channel crabs, while crabs released outside the Channel showed little or no migration. Individual migrations were punctuated by a 7-month hiatus, when crabs remained stationary, coincident with the main period of crab spawning and egg incubation. Incubation commenced earlier in the west, from late October onwards, and brooding locations, determined using tidal geolocation, occurred throughout the species range. With an overall return rate of 34%, our results demonstrate that previous reluctance to tag crabs with relatively high-cost DSTs for fear of loss following moulting is unfounded, and that DSTs can generate precise information with regards life-history metrics that would be unachievable using other conventional means Hunter, E., Eaton, D., Stewart, C., Lawler, A., Smith, M. T. 2013. PLoS ONE. 8, e63991. doi: 10.1371/journal.pone.0063991
Echolocation in Blainville's beaked whales (Mesoplodon densirostris) Here we use sound and movement recording tags to study how deep-diving Blainville's beaked whales (Mesoplodon densirostris) use echolocation to forage in their natural mesopelagic habitat. These whales ensonify thousands of organisms per dive but select only about 25 prey for capture. They negotiate their cluttered environment by radiating sound in a narrow 20° field of view which they sample with 1.5-3 clicks per metre travelled requiring only some 60 clicks to locate, select and approach each prey. Sampling rates do not appear to be defined by the range to individual targets, but rather by the movement of the predator. Whales sample faster when they encounter patches of prey allowing them to search new water volumes while turning rapidly to stay within a patch. This implies that the Griffin search-approach-capture model of biosonar foraging must be expanded to account for sampling behaviours adapted to the overall prey distribution. Beaked whales can classify prey at more than 15 m range adopting stereotyped motor patterns when approaching some prey. This long detection range relative to swimming speed facilitates a deliberate mode of sensory-motor operation in which prey and capture tactics can be selected to optimize energy returns during long breath-hold dives Madsen, P. T., Soto, N. A., Arranz, P., Johnson, M. 2013. J Comp Physiol A. 199, 451- 469. doi: 10.1007/s00359-013-0824-8
Conditional Use of Social and Private Information Guides House-Hunting Ants Social animals can use both social and private information to guide decision making. While social information can be relatively economical to acquire, it can lead to maladaptive information cascades if attention to environmental cues is supplanted by unconditional copying. Ants frequently employ pheromone trails, a form of social information, to guide collective processes, and this can include consensus decisions made when choosing a place to live. In this study, I examine how house-hunting ants balance social and private information when these information sources conflict to different degrees. Social information, in the form of pre-established pheromone trails, strongly influenced the decision process in choices between equivalent nests, and lead to a reduced relocation time. When trails lead to non-preferred types of nest, however, social information had less influence when this preference was weak and no influence when the preference was strong. These results suggest that social information is vetted against private information during the house-hunting
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process in this species. Private information is favoured in cases of conflict and this may help insure colonies against costly wrong decisions Cronin, A. L. 2013. PLoS ONE 8, e64668. doi:10.1371/journal.pone.0064668
Increasing the Usability of Pedestrian Navigation Interfaces by means of Landmark Visibility Analysis Communicating location-specific information to pedestrians is a challenging task which can be aided by user-friendly digital technologies. In this paper, landmark visibility analysis, as a means for developing more usable pedestrian navigation systems, is discussed. Using an algorithmic framework for image-based 3D analysis, this method integrates a 3D city model with identified landmarks and produces raster visibility layers for each one. This output enables an Android phone prototype application to indicate the visibility of landmarks from the user's actual position. Tested in the field, the method achieves sufficient accuracy for the context of use and improves navigation efficiency and effectiveness Delikostidis, I., Engel, J., Retsios, B., van Elzakker, C. P. J. M., Kraak, M. J., Döllner, J. 2013. The Journal of Navigation. 66, 523-537. doi: 10.1017/S0373463313000209
Biomimetic and bio-inspired robotics in electric fish research Weakly electric knifefish have intrigued both biologists and engineers for decades with their unique electrosensory system and agile swimming mechanics. Study of these fish has resulted in models that illuminate the principles behind their electrosensory system and unique swimming abilities. These models have uncovered the mechanisms by which knifefish generate thrust for swimming forward and backward, hovering, and heaving dorsally using a ventral elongated median fin. Engineered active electrosensory models inspired by electric fish allow for close-range sensing in turbid waters where other sensing modalities fail. Artificial electrosense is capable of aiding navigation, detection and discrimination of objects, and mapping the environment, all tasks for which the fish use electrosense extensively. While robotic ribbon fin and artificial electrosense research has been pursued separately to reduce complications that arise when they are combined, electric fish have succeeded in their ecological niche through close coupling of their sensing and mechanical systems. Future integration of electrosense and ribbon fin technology into a knifefish robot should likewise result in a vehicle capable of navigating complex 3D geometries unreachable with current underwater vehicles, as well as provide insights into how to design mobile robots that integrate high bandwidth sensing with highly responsive multidirectional movement Neveln, I. D., Bai, Y., Snyder, J. B., Solberg, J. R., Curet, O. M., Lynch, K. M., MacIver, M. A. 2013. The Journal of Experimental Biology. 216, 2501-2514. doi:10.1242/jeb.082743
Differential Regulation of Adipokines May Influence Migratory Behavior in the White-Throated Sparrow (Zonotrichia albicollis) White-throated sparrows increase fat deposits during pre-migratory periods and rely on these fat stores to fuel migration. Adipose tissue produces hormones and signaling factors in a rhythmic fashion and may be controlled by a clock in adipose tissue or driven by a master clock in the brain. The master clock may convey photoperiodic information from the environment to adipose tissue to facilitate pre-migratory fattening, and adipose tissue may, in turn, release adipokines to indicate the extent of fat energy stores. Here, we present evidence that a change in signal from the adipokines adiponectin and visfatin may act to indicate body condition, thereby influencing an individual's decision to commence migratory
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flight, or to delay until adequate fat stores are acquired. We quantified plasma adiponectin and visfatin levels across the day in captive birds held under constant photoperiod. The circadian profiles of plasma adiponectin in non-migrating birds were approximately inverse the profiles from migrating birds. Adiponectin levels were positively correlated to body fat, and body fat was inversely related to the appearance of nocturnal migratory restlessness. Visfatin levels were constant across the day and did not correlate with fat deposits; however, a reduction in plasma visfatin concentration occurred during the migratory period. The data suggest that a significant change in the biological control of adipokine expression exists between the two migratory conditions and we propose a role for adiponectin, visfatin and adipose clocks in the regulation of migratory behaviors Stuber, E. F., Verpeut, J., Horvat-Gordon, M., Ramachandran, R. & Bartell, P. A. 2013 PLoS ONE 8, e59097 doi:10.1371/journal.pone.0059097.
Rejoinder: challenge and opportunity in the study of ungulate migration amid environmental change 1st paragraph: Increasingly, animals that migrate long distances to exploit seasonal habitats must traverse political boundaries capable of altering the very ecological gradients that promote migratory behavior. This transboundary aspect of migration presents many new challenges and opportunities for research and conservation (e.g., Bolger et al. 2008, Taillon et al. 2012). Work to date has often focused on physical barriers to movement (roads, fences, and housing and energy development) that can threaten migratory populations to varying degrees (Holdo et al.2011, Sawyer et al. 2013). However, even in the absence of conspicuous barriers, political and jurisdictional boundaries can bring dramatic differences in land use and conservation policy. What happens to migratory populations when these boundaries alter the resources and refuges that they seek on their seasonal journeys? Middleton, A. D., Kauffman, M. J., McWhirter, D. E., Cook, J. G., Cook, R. C., Nelson, A. A., Jimenez, M. D., Klaver, R. W. 2013. Ecology. 94, 1280-1286. doi: 10.1890/12-2142.1
Environmental change and the evolution of migration 1st paragraph Perhaps the most difficult challenge in evolutionary biology is to ‘‘explain’’ existing patterns in light of environmental, genetic, and physical constraints (Gould and Lewontin 1979). The reason is obvious: Because we can only observe the resulting pattern, causes for the underlying process that produced that pattern will always prove elusive. Yet the mountains of data accumulated by ecological and evolutionary studies linked with rapid environmental changes that have occurred over the past few decades now present a remarkable pportunity to witness evolution in action. Such is the opportunity hinted at by Middleton et al.’s (2013; hereafter referred to as Middleton et al.) paper comparing pregnancy rates and cow : calf ratios of resident elk (Cervus elaphus) living outside Yellowstone National Park (USA) to those of elk that migrate seasonally. The latter use montane areas during the summer months and lowland habitat similar to that of residents during the winter months. All other things being equal, their data suggests a substantial decline in the rate of offspring recruitment of migratory elk, compared to that of residents, likely driven both by phenological changes and an upsurge in predation from large carnivores. This would suggest that there might be strong selection underway, disfavoring migration. Fryxell, J. M., Holt, R. D. 2013 94, 1274-1279. doi:10.1890/12-0668.1
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Animal migration amid shifting patterns of phenology and predation: lessons from a Yellowstone elk herd Migration is a striking behavioral strategy by which many animals enhance resource acquisition while reducing predation risk. Historically, the demographic benefits of such movements made migration common, but in many taxa the phenomenon is considered globally threatened. Here we describe a long-term decline in the productivity of elk (Cervus elaphus) that migrate through intact wilderness areas to protected summer ranges inside Yellowstone National Park, USA. We attribute this decline to a long-term reduction in the demographic benefits that ungulates typically gain from migration. Among migratory elk, we observed a 21-year, 70% reduction in recruitment and a 4-year, 19% depression in their pregnancy rate largely caused by infrequent reproduction of females that were young or lactating. In contrast, among resident elk, we have recently observed increasing recruitment and a high rate of pregnancy. Landscape-level changes in habitat quality and predation appear to be responsible for the declining productivity of Yellowstone migrants. From 1989 to 2009, migratory elk experienced an increasing rate and shorter duration of green-up coincident with warmer spring-summer temperatures and reduced spring precipitation, also consistent with observations of an unusually severe drought in the region. Migrants are also now exposed to four times as many grizzly bears (Ursus arctos) and wolves (Canis lupus) as resident elk. Both of these restored predators consume migratory elk calves at high rates in the Yellowstone wilderness but are maintained at low densities via lethal management and human disturbance in the year-round habitats of resident elk. Our findings suggest that large-carnivore recovery and drought, operating simultaneously along an elevation gradient, have disproportionately influenced the demography of migratory elk. Many migratory animals travel large geographic distances between their seasonal ranges. Changes in land use and climate that disparately influence such seasonal ranges may alter the ecological basis of migratory behavior, representing an important challenge for, and a powerful lens into, the ecology and conservation of migratory taxa Middleton, A. D., Kauffman, M. J., McWhirter, D. E., Cook, J. G., Cook, R. C., Nelson, A. A., Jimenez, M. D., Klaver, R. W. 2013 Ecology. 94, 1245-1256. doi: 10.1890/11-2298.1
Carry-over effects from breeding modulate the annual cycle of a long-distance migrant: an experimental demonstration Carry-over effects relate to events or processes that influence individual performance in a subsequent season, but their occurrence in the annual cycle of migratory avian taxa is seldom studied. We investigated if different levels of resource allocation to reproduction may result in carry-over effects that change the timing and destination of long-distance migration. We reduced the parental investment of Cory's Shearwaters Calonectris diomedea by removing their chick at an early stage. When compared to individuals with greater parental investment (controls that raised chicks to close to fledging), manipulated birds started most stages of migration sooner and returned to the colony earlier at the start of the following breeding season. Late arrival in the subsequent nesting season increased the probability of skipping a breeding year. Manipulated males were less likely to engage in long- distance migration, which supports the idea that partial migration is condition dependent. Our study demonstrates experimentally that energetic or time-dependent costs of reproduction may have an enduring impact on migration schedule and on nonbreeding geographical distribution of long-distance migrants, which may also influence the ability to breed in the following season. Read More: http://www.esajournals.org/doi/abs/10.1890/12-2177.1
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Catry, P., Dias, M. P., Phillips, R. A., Granadeiro, J. P. 2013. Ecology. 94, 1230-1235 doi: 10.1890/12-2177.1
Sun Compass Orientation Helps Coral Reef Fish Larvae Return to Their Natal Reef Reef fish sustain populations on isolated reefs and show genetic diversity between nearby reefs even though larvae of many species are swept away from the natal site during pelagic dispersal. Retention or recruitment to natal reefs requires orientation capabilities that enable larvae to find their way. Although olfactory and acoustically based orientation has been implicated in homing when larvae are in the reef’s vicinity, it is still unclear how they cope with greater distances. Here we show evidence for a sun compass mechanism that can bring the larvae to the vicinity of their natal reef. In a circular arena, pre-settlement larvae and early settlers (<24 hours>) of the cardinal fish, Ostorhinchus doederleini, showed a strong SSE directional swimming response, which most likely has evolved to compensate for the locally prevailing large scale NNW current drift. When fish were clock-shifted 6 hours, they changed their orientation by ca. 180° as predicted by the tropical sun curve at One Tree Island, i.e. they used a time-compensated sun compass. Furthermore, the fish oriented most consistently at times of the day when the sun azimuth is easy to determine. Microsatellite markers showed that the larvae that had just arrived at One Tree Island genetically belonged to either the local reef population or to Fitzroy Reef located 12 kilometers to the SSE. The use of a sun compass adds a missing long-distance link to the hierarchy of other sensory abilities that can direct larvae to the region of origin, including their natal reef. Predominant local recruitment, in turn, can contribute to genetic isolation and potential speciation Mouritsen, H., Atema, J., Kingsford, M. J. & Gerlach, G. 2013. PLoS ONE 8, e66039. doi:10.1371/journal.pone.0066039
Advances in tracking small migratory birds: a technical review of light-level geolocation Light-level geolocation data loggers, or geologgers, have recently been miniaturized to the extent that they can be deployed on small songbirds, allowing us to determine many previously unknown migration routes, breeding locations, and wintering sites. Use of geologgers on small birds has great potential to help address major research and conservation questions, but the method is not without its shortcomings. Among these shortcomings are the need to recapture birds after they have carried a device throughout a migration cycle and the potential for the devices to affect survival and behavior. We examined return rates of birds with geologgers in published and unpublished studies and found no evidence of a general negative effect of geologgers on survival, although there were a few individual studies where such an effect was evident. From these same studies, we found that most currently used harness materials are equivalent in terms of failure rates, and the most reliable geologgers are those made by the British Antarctic Survey (although these were also the largest geologgers used in the studies we examined). With regard to analysis methods, we believe there is much room for improvement. Use of online archiving of both data and analysis parameters would greatly improve the repeatability and transparency of geologger research Bridge, E. S., Kelly, J. F., Contina, A., Gabrielson, R. M., MacCurdy, R. B., Winkler, D. W. 2013. Journal of Field Ornithology. 84, 121-137. doi: 10.1111/jofo.12011
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The significance of midsummer movements of Autographa gamma: Implications for a mechanistic understanding of orientation behavior in a migrant moth The silver Y moth Autographa gamma undertakes windborne spring and fall migrations between winter breeding regions around the Mediterranean and summer breeding regions in northern Europe. Flight behaviors facilitating these migrations include: (i) selection of seasonally-favorable tailwinds; (ii) flying at the altitude of the fastest winds; (iii) adopting flight headings that partially counteract crosswind drift; and (iv) seasonal reversal of preferred directions between spring and fall. In the UK, radar measurements indicate that migratory activity is pronounced during the spring and fall, but is usually very low during midsummer (July). However, an atypically intense period of high-altitude flight was recorded during July 2006, and in this study we compare the flight behavior of A. gamma during these midsummer movements with the more typical spring and fall migrations. During July 2006, activity was most intense at significantly lower altitudes than occurred in spring or fall, and was not associated with the height of the fastest winds; consequently displacement speeds were significantly slower. The most striking difference was an absence of tailwind selectivity in July with windborne movements occurring on almost every night of the month and on tailwinds from all directions. Finally, orientation behavior was quantitatively different during July, with significantly greater dispersion of flight headings and displacements than observed in spring and fall. We discuss mechanisms which could have caused these differences, and conclude that a lack of appropriate photoperiod cues during development of the summer generation resulted in randomly-oriented 'dispersive' movements that were strikingly different from typical seasonal migrations Chapman, J. W., Lim, K. S., Reynolds, D. R. 2013 Current Zoology. 59, 360-370
Apparent dissociation of photoperiodic time measurement between vernal migration and breeding under dim green light conditions in Gambel's white- crowned sparrow Zonotrichia leucophrys gambelii In seasonally breeding birds, the annual cycle of photoperiod is a principal environmental cue for temporal arrangement of different life-history stages, such as migration and breeding. In the past, most research has focused on the mechanisms of photoperiodic control of breeding with less attention paid to migration. In Gambel's white-crowned sparrow Zonotrichia leucophrys gambelii (GWCS), photoreceptors for induction of breeding are known to reside in the basal hypothalamus. However, it is unknown whether the sites of photoperiodic reception for vernal migration are the same as those for breeding. Therefore, we hypothesized that they may be controlled separately. In this study, we exposed photosensitive GWCSs to low-penetration green light (wavelength at 510 nm) under a regime of 1 lux during the day and <0.1 lux at night, and switched the photoperiodic conditions from short day (10 h daytime) to long day (18 h daytime). The results showed that the experimental birds developed traits associated with vernal migration including mass increase, fat deposition and migratory restlessness behavior when transferred from short day to long day green light cycles, while control birds maintained continuously on short day green light conditions did not express any migration related characteristics. Neither experimental nor control groups showed gonadal recrudescence under either green light cycles. In support of our hypothesis, we were able to apparently dissociate the photoperiodic responses regulating vernal migration and breeding, which suggests separate mechanisms of photoperiodic time measurement. Such distinct photoperiodic mechanisms may drive the fine-tuned temporal arrangement of the two life history stages Wang, G., Ramenofsky, M., Wingfield, J. C. 2013. Current Zoology. 59, 349-359
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Revealing the control of migratory fueling: An integrated approach combining laboratory and field studies in northern wheatears Oenanthe oenanthe Migratory birds rely on fueling prior to migratory flights. Fueling in migrants is controlled by intrinsic as well as extrinsic factors. From captive studies we have started understanding the internal mechanisms controlling bird migration. Field studies have demonstrated the effects of external factors, such as food availability, weather, competitors, parasites or diseases, on the stopover behavior of migrants. However, an integrated approach is still missing to study coherently how the innate migration program interacts with the varying environmental cues and to estimate the contribution of the innate migration program and the environment to realized migration. The northern wheatear Oenanthe oenanthe offers a unique opportunity for integrated studies. It breeds across almost the whole Holarctic with just a "gap" between eastern Canada and Alaska. All breeding populations overwinter in sub-Saharan Africa which makes the northern wheatear one of the most long-distant migratory songbirds with extraordinary long non-stop flights across oceans. It is a nocturnal migrant which travels without parental or social aid/guidance. Thus, young birds rely entirely on endogenous mechanisms of timing, route selection and fueling on their first outbound migration. By establishing indoor housing under controlled conditions the endogenous control mechanisms of northern wheatear migration could be revealed. At the same time, environmental factors controlling fueling could be investigated in the field. On migration wheatears occur in a variety of habitats with sparse vegetation where their stopover behavior could be quantitatively studied in the light of "optimal migration" theory by the use of remote balances, radio-tagging and even experimentally manipulated food availability. The present paper summarizes our approach to understand the control of migration in northern wheatears by combining field and laboratory studies at various spatial and temporal scales, and linking various sub-disciplines Bairlein, F., Dierschke, J., Delingat, J., Eikenaar, C., Maggini, I., Bulte, M., Schmaljohann, H. 2013. Current Zoology. 59, 381-392
Lipid reserves and immune defense in healthy and diseased migrating monarchs Danaus plexippus Recent studies suggest that the energetic demands of long-distance migration might lower the pool of resources available for costly immune defenses. Moreover, migration could amplify the costs of parasitism if animals suffering from parasite-induced damage or depleted energy reserves are less able to migrate long distances. We investigated relationships between long-distance migration, infection, and immunity in wild fall-migrating monarch butterflies Danaus plexippus. Monarchs migrate annually from eastern North America to central Mexico, accumulating lipids essential for migration and winter survival as they travel southward. Monarchs are commonly infected by the debilitating protozoan parasite Ophryocystis elektroscirrha (OE). We collected data on lipid reserves, parasite loads, and two immune measures (hemocyte concentration and phenoloxidase activity) from wild monarchs migrating through north GA (USA) to ask whether (1) parasite infection negatively affects lipid reserves, and (2) greater investment in lipid reserves is associated with lower immune measures. Results showed that monarchs sampled later in the fall migration had lower but not significantly different immune measures and significantly higher lipid reserves than those sampled earlier. Lipid measures correlated negatively but only nearly significantly with one measure of immune defense (phenoloxidase activity) in both healthy and infected monarchs, but did not depend on monarch infection status or parasite load. These results provide weak support for a trade-off between energy reserves and immune defense in migrants, and suggest that previously-demonstrated costs of OE infection for monarch migration are not
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caused by depleted lipid reserves Satterfield, D. A., Wright, A. E., Altizer, S. 2013 Current Zoology. 59, 393-402
Premigratory fat metabolism in hummingbirds: A rumsfeldian approach Hummingbird migration is a remarkable feat, given the small body sizes of migratory species, their high metabolic rates during flight and the long distances traveled using fat to fuel the effort. Equally remarkable is the ability of premigratory hummingbirds in the wild to accumulate fat, synthesized from sugar, at rates as high as 10% of body mass per day. This paper summarizes, using Rumsfeldian terminology, "known knowns" concerning the energetics of hummingbird migration and premigratory fattening. Energy metabolism during hover-feeding on floral nectar is fueled directly by dietary sugar through the pathway recently named the "sugar oxidation cascade". However, flight without feeding for more than a few minutes requires shifting to fat as a fuel. It is proposed that behavior and metabolic fuel choice are coadapted to maximize the rate of fat deposition during premigratory fattening. The hummingbird liver appears to possess extraordinarily high capacities for fatty acid synthesis. The analysis of "known knowns" leads to identification of "known unknowns", e.g., the fates of dietary glucose and fructose, the regulation of fat metabolism and metabolic interactions between liver and adipose tissue. The history of science behooves recognition of "unknown unknowns" that, when discovered serendipitously, might shed new light on fundamental mechanisms as well as human pathological conditions Suarez, R. K. 2013 Current Zoology 59, 371-380
Development of the navigational system in homing pigeons: increase in complexity of the navigational map In the present study we analysed GPS-recorded tracks from pigeons of different ages from 11 sites between 3.6 and 22.1 km from the home loft, which revealed changes in the navigational system as the birds grew older and became more experienced. The efficiency of juveniles in their first year of life, at only 0.27, was rather low, indicating that the young birds covered more than three times the direct distance home. In the second year, after a standard training programme, the efficiency of the same birds increased to 0.80 and was no longer different from that of older pigeons. The short-term correlation dimension, a variable that reflects the number of factors involved in the navigational process, also increased with age. In juveniles, it was markedly lower than in the other two groups, but even in yearlings it was still significantly lower than that of old pigeons, indicating that the navigational map of yearlings is still developing. Our results indicate that the map system, although functional in the first year of life, continues to become more complex GÇô older pigeons seem to either consider more navigational factors than younger ones or at least weigh the same factors differently Schiffner, I., Wiltschko, R. 2013 The Journal of Experimental Biology. 216, 2675-2681. doi: 10.1242/jeb.085662
Mapping the navigational knowledge of individually foraging ants, Myrmecia croslandi Ants are efficient navigators, guided by path integration and visual landmarks. Path integration is the primary strategy in landmark-poor habitats, but landmarks are readily used when available. The landmark panorama provides reliable information about heading direction, routes and specific location. Visual memories for guidance are often acquired along routes or near to significant places. Over what area can such locally acquired
39 memories provide information for reaching a place? This question is unusually approachable in the solitary foraging Australian jack jumper ant, since individual foragers typically travel to one or two nest-specific foraging trees. We find that within 10 m from the nest, ants both with and without home vector information available from path integration return directly to the nest from all compass directions, after briefly scanning the panorama. By reconstructing panoramic views within the successful homing range, we show that in the open woodland habitat of these ants, snapshot memories acquired close to the nest provide sufficient navigational information to determine nest-directed heading direction over a surprisingly large area, including areas that animals may have not visited previously Narendra, A., Gourmaud, S., Zeil, J. 2013 Proceedings of the Royal Society B: Biological Sciences. 280, doi: 10.1098/rspb.2013.0683
Use of a light-dependent magnetic compass for y-axis orientation in European common frog (Rana temporaria) tadpoles We provide evidence for the use of a magnetic compass for y-axis orientation (i.e., orientation along the shore-deep water axis) by tadpoles of the European common frog (Rana temporaria). Furthermore, our study provides evidence for a wavelength-dependent effect of light on magnetic compass orientation in amphibians. Tadpoles trained and then tested under full-spectrum light displayed magnetic compass orientation that coincided with the trained shore-deep water axes of their training tanks. Conversely, tadpoles trained under long-wavelength (?500 nm) light and tested under full-spectrum light, and tadpoles trained under full-spectrum light and tested under long-wavelength (?500 nm) light, exhibited a 90° shift in magnetic compass orientation relative to the trained y-axis direction. Our results are consistent with earlier studies showing that the observed 90° shift in the direction of magnetic compass orientation under long-wavelength (?500 nm) light is due to a direct effect of light on the underlying magnetoreception mechanism. These findings also show that wavelength-dependent effects of light do not compromise the function of the magnetic compass under a wide range of natural lighting conditions, presumably due to a large asymmetry in the relatively sensitivity of antagonistic short- and long-wavelength inputs to the light-dependent magnetic compass Diego-Rasilla, F. J., Luengo, R. M., Phillips, J. B. 2013 J Comp Physiol A. 199, 619-628. doi: 10.1007/s00359-013-0811-0
Automated long-term tracking and social behavioural phenotyping of animal colonies within a semi-natural environment Social behaviour has a key role in animal survival across species, ranging from insects to primates and humans. However, the biological mechanisms driving natural interactions between multiple animals, over long-term periods, are poorly studied and remain elusive. Rigorous and objective quantification of behavioural parameters within a group poses a major challenge as it requires simultaneous monitoring of the positions of several individuals and comprehensive consideration of many complex factors. Automatic tracking and phenotyping of interacting animals could thus overcome the limitations of manual tracking methods. Here we report a broadly applicable system that automatically tracks the locations of multiple, uniquely identified animals, such as mice, within a semi-natural setting. The system combines video and radio frequency identified tracking data to obtain detailed behavioural profiles of both individuals and groups. We demonstrate the usefulness of these data in characterizing individual phenotypes, interactions between pairs and the collective social organization of groups. Weissbrod, A., Shapiro, A., Vasserman, G., Edry, L., Dayan, M., Yitzhaky, A.,
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Hertzberg, L., Feinerman, O., Kimchi, T. 2013. Nat Commun. 4, doi: 10.1038/ncomms3018
Projected climate-driven faunal movement routes Historically, many species moved great distances as climates changed. However, modern movements will be limited by the patterns of human-dominated landscapes. Here, we use a combination of projected climate-driven shifts in the distributions of 2903 vertebrate species, estimated current human impacts on the landscape, and movement models, to determine through which areas in the western hemisphere species will likely need to move to track suitable climates. Our results reveal areas with projected high densities of climate- driven movements including, the Amazon Basin, the southeastern United States and southeastern Brazil. Some of these regions, such as southern Bolivia and northern Paraguay, contain relatively intact landscapes, whereas others such as the southeastern United States and Brazil are heavily impacted by human activities. Thus, these results highlight both critical areas for protecting lands that will foster movement, and barriers where human land-use activities will likely impede climate-driven shifts in species distributions Lawler, J. J., Ruesch, A. S., Olden, J. D., McRae, B. H. 2013. Ecology Letters. Online early. doi: 10.1111/ele.12132
Movements and dispersal of farmed Atlantic salmon following a simulated- escape event One of the major challenges for understanding the ecological impact of escaped farmed Atlantic salmon (Salmo salar L.) is predicting their dispersal patterns after an escape event. Here, we quantify the behaviour of escaped farmed salmon using a simulated-escape experiment within a Norwegian fjord system. Thirty-seven individuals were tagged with acoustic transmitters and their spatial distribution, horizontal movements and diving behaviour was monitored throughout the fjord and accompanying rivers using 29 acoustic receivers. A rapid movement away from the release site occurred. There was no movement into the rivers feeding the fjord and there was no preference for residence at the fish farms: nearly a third of the individuals had a final detection in the outer part of the fjord and no detections occurred from approximately 2 months after release. As it is unlikely that all fish died or remained undetected within the study area it is reasonable to assume that a substantial proportion of the fish moved out of the fjord system. If a recapture program is not implemented immediately after an escape event, we recommend spreading potential recapture efforts over a relatively large area Solem, O., Hedger, R. D., Urke, H. A., Kristensen, T., Okland, F., Ulvan, E. M., Uglem, I. 2013. Environ Biol Fish. 96, 927-939. doi: 10.1007/s10641-012-0088-0
Site fidelity and homing behaviour in intertidal fishes The theory of ecological cognition poses that the brains and behaviour of animals are shaped by the environmental challenges they face in their everyday lives. Site fidelity and homing ability was tested for five species of intertidal rock pool fish by tagging and displacing them to new rock pools at various distances from their 'home' rock pools. Three of the species were rock pool specialists whilst the remaining two spend a small proportion of their life in rock pools during early ontogeny. The three specialists showed strong site fidelity with >50 % of individuals found in the same pool 42 days after tagging. In contrast, the non-specialist species showed low fidelity and poor homing abilities. Homing success in the rock pool specialists remained relatively stable as displacement distance increased. The effect of body size on homing ability was species dependent, with only one species showing a significantly
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greater tendency to home with increasing size White, G., Brown, C. 2013. Mar Biol. 160, 1365-1372. doi: 10.1007/s00227-013-2188- 6
Satellite telemetry reveals behavioural plasticity in a green turtle population nesting in Sri Lanka Satellite transmitters were deployed on ten green turtles (Chelonia mydas) nesting in Rekawa Sanctuary (RS-80.851°E 6.045°N), Sri Lanka, during 2006 and 2007 to determine inter- nesting and migratory behaviours and foraging habitats. Nine turtles subsequently nested at RS and demonstrated two inter-nesting strategies linked to the location of their residence sites. Three turtles used local shallow coastal sites within 60 km of RS during some or all of their inter-nesting periods and then returned to and settled at these sites on completion of their breeding seasons. In contrast, five individuals spent inter-nesting periods proximate to RS and then migrated to and settled at distant (>350 km) shallow coastal residence sites. Another turtle also spent inter-nesting periods proximate to RS and then migrated to a distant oceanic atoll and made forays into oceanic waters for 42 days before transmissions ceased. This behavioural plasticity informs conservation management beyond protection at the nesting beach Richardson, P. B., Broderick, A. C., Coyne, M. S., Ekanayake, L., Kapurusinghe, T., Premakumara, C., Ranger, S., Saman, M. M., Witt, M. J., Godley, B. J. 2013. Mar Biol. 160, 1415-1426. doi: 10.1007/s00227-013-2194-8
Context-dependent diel behavior of upstream-migrating anadromous fishes Variability is a hallmark of animal behavior and the degree of variability may fluctuate in response to environmental or biological gradients. For example, diel activity patterns during reproductive migrations often differ from those in non-breeding habitats, reflecting trade- offs among efficient route selection, reproductive phenology, and risk avoidance. In this study, we tested the hypothesis that diel movements of anadromous fishes differ among freshwater migration habitats. We analyzed diel movement data from ~13 000 radio-, PIT-, and acoustic-tagged adult fishes from five Columbia River species: Chinook salmon, Oncorhynchus tshawytscha; sockeye salmon, O. nerka; steelhead, O. mykiss; Pacific lamprey, Entosphenus tridentatus; and American shad, Alosa sapidissima. All five species were active during most of the diel cycle in low-gradient, less hydraulically complex reservoir and riverine habitats. Movement shifted to predominantly diurnal (salmonids and American shad) or nocturnal (Pacific lamprey) at hydroelectric dam fishways where hydraulic complexity and predator density were high. Results suggest that context- dependent behaviors are common during fish migrations, and that diel activity patterns vary with the degree of effort or predation risk required for movement Keefer, M., Caudill, C., Peery, C., Moser, M. 2013. Environ Biol Fish. 96, 691-700. doi: 10.1007/s10641-012-0059-5
Migration and dispersal patterns of bats and their influence on genetic structure. Bats are important ecosystems service providers, make a significant contribution to biodiversity and can be important pests and disease vectors. In spite of this, information on their migration and dispersal patterns is limited. 2. In temperate bats, migration is most evident in females. This reflects seasonal differences in their habitat requirements, and the fact that seasonally suitable sites can be geographically distant. Tropical bats mainly migrate to track variation in food availability.
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3. Little direct information is available on the patterns and drivers of bat dispersal, although drivers may include mate competition and inbreeding avoidance. In many temperate species, differential energy requirements and local resource competition among the sexes drive sexual segregation in the summer: females remain philopatric to their natal region, and frequently to their natal colony, while males disperse. In contrast, many tropical Pteropodidae form single-male/multi-female groups in which local resource defence contributes to female-biased or all-offspring dispersal from the natal site. 4. Population genetic studies are the most common source of evidence used to infer the spatial dynamics of bats. As expected, migratory species tend to have less genetically structured populations over large geographical scales due to mating outside of breeding areas, weak migratory connectivity and long-distance movements. In contrast and as expected, populations of sedentary species tend to be more differentiated at smaller geographical scales. 5. Despite this general pattern, a range of factors, including historical events, dispersal capabilities, and behavioural, ecological and geographical barriers, are implicated in the genetic partitioning of bat populations, irrespective of movement patterns. These factors limit the study of bat movements using only genetic methods. 6. Combining population genetics with other methods, such as mark-recapture, tracking or stable isotope analysis, should provide more insight into the movements of these ecologically and economically important species. Moussy, C., Hosken, D. J., Mathews, F., Smith, G. C., Aegerter, J. N., Bearhop, S. 2013. Mammal Review. 43, 183-195. doi: 10.1111/j.1365-2907.2012.00218.x
Fall movements of Red-headed Woodpeckers in South Carolina. Fall migration of Red-headed Woodpeckers (Melanerpes erythrocephalus) can be erratic, with departure rates, directions, and distances varying among populations and individuals. We report fall migration departure dates, rates, and routes, and the size of fall home ranges of 62 radio-tagged Red-headed Woodpeckers in western South Carolina. Rates of fall migration differed among years; all radio-tagged woodpeckers migrated in 2005 (15 of 15), none (0 of 23) migrated in 2006, and 54.2% (13 of 24) migrated in 2007. Of 28 woodpeckers that left their breeding territories, we relocated eight either en route or on their fall home ranges. These woodpeckers migrated short distances (4.3-22.2 km) south along the floodplain forest of a large creek. The variable migration patterns we observed indicate that Red-headed Woodpeckers may best be described as facultative migrants. We determined the home range sizes of 13 woodpeckers in both seasons, regardless of whether they migrated, and fall home ranges were smaller (mean = 1.12 ha) than summer home ranges (mean = 3.23 ha). Fall-winter movements of Red-headed Woodpeckers were concentrated on mast-producing oak (Quercus spp.) trees, which may have restricted home range sizes. The partial migration we observed in 2007 suggests that factors other than mast crop variability may also influence migration patterns because woodpeckers that year responded to the same annual mast crop in different ways, with some migrating and some remaining on breeding season home ranges during the fall. Vukovich, M., Kilgo, J. C. 2013. 84, 193-200. doi: 10.1111/jofo.12018
Effect of neck collars on the body condition of migrating Greater Snow Geese Markers are widely used to study behavior, migration, and the life history traits of birds such as survival, dispersal, and reproductive success. The presence of neck collars has been shown to impact the breeding propensity of adult female Greater Snow Geese (Chen caerulescens atlantica), but not their survival rates. We evaluated the hypothesis that the
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reduction in breeding propensity in neck-collared birds was due to a reduction in the body condition of these long-distance migrants that rely on a partial capital breeding strategy. Our study was conducted during 4 consecutive years along the St. Lawrence estuary in Quebec, Canada, a major spring staging area for these geese. We captured and marked 2552 geese with collars and 34 were recaptured in subsequent years at the same site. After controlling for confounding variables such as year and date of capture, we found that the presence of a neck collar reduced body condition of females during spring staging. Female Greater Snow Geese lost an average of 105.5 ± 39.1 (SE) g (4% of body mass) after carrying a collar for 1 yr and an average of 81.9 ± 43.6 g compared to original mass when recaptured 2 or 3 yr later. Our results suggest that the previously reported reduction in breeding propensity of neck-collared geese may be due to a reduction in body condition during spring staging. Neck collars could negatively affect the body condition of female Greater Snow Geese by increasing their energy expenditure (due to increased drag during flight or to chronic stress) or reducing their foraging efficiency. Legagneux, P., Simard, A. A., Gauthier, G., Bety. 2013. Journal of Field Ornithology. 84, 201-209. doi: 10.1111/jofo.12019
Migratory Reed Warblers Need Intact Trigeminal Nerves to Correct for a 1,000 km Eastward Displacement Several studies have shown that experienced night-migratory songbirds can determine their position, but it has remained a mystery which cues and sensory mechanisms they use, in particular, those used to determine longitude (east–west position). One potential solution would be to use a magnetic map or signpost mechanism like the one documented in sea turtles. Night-migratory songbirds have a magnetic compass in their eyes and a second magnetic sense with unknown biological function involving the ophthalmic branch of the trigeminal nerve (V1). Could V1 be involved in determining east–west position? We displaced 57 Eurasian reed warblers (Acrocephalus scirpaceus) with or without sectioned V1. Sham operated birds corrected their orientation towards the breeding area after displacement like the untreated controls did. In contrast, V1-sectioned birds did not correct for the displacement. They oriented in the same direction after the displacement as they had done at the capture site. Thus, an intact ophthalmic branch of the trigeminal nerve is necessary for detecting the 1,000 km eastward displacement in this night-migratory songbird. Our results suggest that V1 carries map-related information used in a large-scale map or signpost sense that the reed warblers needed to determine their approximate geographical position and/or an east–west coordinate. Kishkinev, D., Chernetsov, N., Heyers, D. & Mouritsen, H. 2013. PLoS ONE 8, e65847. doi:10.1371/journal.pone.0065847
Perceiving space and optical cues via a visuo-tactile sensory substitution system: a methodological approach for training of blind subjects for navigation A methodological approach to perceptual learning was used to allow both early blind subjects (experimental group) and blindfolded sighted subjects (control group) to experience optical information and spatial phenomena, on the basis of visuo-tactile information transmitted by a 64-taxel pneumatic sensory substitution device. The learning process allowed the subjects to develop abilities in spatial localisation, shape recognition (with generalisation to different points of view), and monocular depth cue interpretation. During the training phase, early blind people initially experienced more difficulties than blindfolded sighted subjects (having previous perceptual experience of perspective) with interpreting and using monocular depth cues. The amelioration of the performance for all
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blind subjects during training sessions and the quite similar level of performance reached by two groups in the final navigation tasks suggested that early blind people were able to develop and apply cognitive understanding of depth cues. Both groups showed generalisation of the learning from the initial phases to cue identification in the maze, and subjectively experienced shapes facing them. Subjects’ performance depended not only on their perceptual experience but also on their previous spatial competencies Segond, H., Weiss, D., Kawalec, M. & Sampaio, E. 2013. Perception 42, 508-528. doi:10.1068/p6339
Complementary Roles of the Hippocampus and the Dorsomedial Striatum during Spatial and Sequence-Based Navigation Behavior We investigated the neural bases of navigation based on spatial or sequential egocentric representation during the completion of the starmaze, a complex goal-directed navigation task. In this maze, mice had to swim along a path composed of three choice points to find a hidden platform. As reported previously, this task can be solved by using two hippocampal- dependent strategies encoded in parallel i) the allocentric strategy requiring encoding of the contextual information, and ii) the sequential egocentric strategy requiring temporal encoding of a sequence of successive body movements associated to specific choice points. Mice were trained during one day and tested the following day in a single probe trial to reveal which of the two strategies was spontaneously preferred by each animal. Imaging of the activity-dependent gene c-fos revealed that both strategies are supported by an overlapping network involving the dorsal hippocampus, the dorsomedial striatum (DMS) and the medial prefrontal cortex. A significant higher activation of the ventral CA1 subregion was observed when mice used the sequential egocentric strategy. To investigate the potential different roles of the dorsal hippocampus and the DMS in both types of navigation, we performed region-specific excitotoxic lesions of each of these two structures. Dorsal hippocampus lesioned mice were unable to optimally learn the sequence but improved their performances by developing a serial strategy instead. DMS lesioned mice were severely impaired, failing to learn the task. Our data support the view that the hippocampus organizes information into a spatio-temporal representation, which can then be used by the DMS to perform goal-directed navigation Fouquet, C. l., Babayan, B. n. d. M., Watilliaux, A. l., Bontempi, B., Tobin, C. & Rondi-Reig, L. 2013. PLoS ONE 8, e67232. doi:10.1371/journal.pone.0067232
Annual rhythms that underlie phenology: biological time-keeping meets environmental change Seasonal recurrence of biological processes (phenology) and its relationship to environmental change is recognized as being of key scientific and public concern, but its current study largely overlooks the extent to which phenology is based on biological time- keeping mechanisms. We highlight the relevance of physiological and neurobiological regulation for organisms’ responsiveness to environmental conditions. Focusing on avian and mammalian examples, we describe circannual rhythmicity of reproduction, migration and hibernation, and address responses of animals to photic and thermal conditions. Climate change and urbanization are used as urgent examples of anthropogenic influences that put biological timing systems under pressure. We furthermore propose that consideration of Homo sapiens as principally a ‘seasonal animal’ can inspire new perspectives for understanding medical and psychological problems Helm, B., Ben-Shlomo, R., Sheriff, M. J., Hut, R. A., Foster, R., Barnes, B. M., Dominoni, D. 2013. Proceedings of the Royal Society B: Biological Sciences. 280, 49, 563-579
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doi:10.1098/rspb.2013.0016
Patterns and influences on Dolly Varden migratory timing in the Chignik Lakes, Alaska, and comparison of populations throughout the northeastern Pacific and Arctic oceans Dolly Varden (Salvelinus malma) are a facultatively anadromous salmonid common around much of the North Pacific Rim, but little is known about the environmental factors affecting the timing and diversity of their migration. We combined telemetry of anadromous fish with long-term monitoring of Dolly Varden upstream migration timing and environmental data in the Chignik Lakes watershed in Alaska and then compared the timing data with that of other streams where only count data were available. Telemetry revealed two upstream migration modes: midsummer and late fall at the Chignik Lakes. Weir counts indicated that timing fluctuated markedly over the monitoring period (1996-2011) and was negatively correlated with June sea surface temperature. The relationship between sea surface temperature and migration timing in other watersheds with long-term records was as follows: negative (Buskin River), positive (Auke Creek), or nonexistent (Goodnews and Kanektok rivers). Among 18 streams and rivers throughout the eastern Pacific range of Dolly Varden, median upstream migration date increased with latitude. Overall, Dolly Varden migration timing is more variable, protracted, and more strongly influenced by local sea surface temperatures than is typical of semelparous salmonids. These results are likely indicative of other iteroparous salmonids in Pacific waters that share similar environments and life-history characteristics Bond, M. H., Quinn, T. P. 2013. Canadian Journal of Fisheries and Aquatic Sciences. 70, 655- 665. doi:10.1139/cjfas-2012-0416
Blue whales respond to simulated mid-frequency military sonar Mid-frequency military (1-10 kHz) sonars have been associated with lethal mass strandings of deep-diving toothed whales, but the effects on endangered baleen whale species are virtually unknown. Here, we used controlled exposure experiments with simulated military sonar and other mid-frequency sounds to measure behavioural responses of tagged blue whales (Balaenoptera musculus) in feeding areas within the Southern California Bight. Despite using source levels orders of magnitude below some operational military systems, our results demonstrate that mid-frequency sound can significantly affect blue whale behaviour, especially during deep feeding modes. When a response occurred, behavioural changes varied widely from cessation of deep feeding to increased swimming speed and directed travel away from the sound source. The variability of these behavioural responses was largely influenced by a complex interaction of behavioural state, the type of mid-frequency sound and received sound level. Sonar-induced disruption of feeding and displacement from high-quality prey patches could have significant and previously undocumented impacts on baleen whale foraging ecology, individual fitness and population health Goldbogen, J. A., Southall, B. L., DeRuiter, S. L., Calambokidis, J., Friedlaender, A. S., Hazen, E. L., Falcone, E. A., Schorr, G. S., Douglas, A., Moretti, D. J., Kyburg, C., McKenna, M. F., Tyack, P. L. 2013. Proceedings of the Royal Society B: Biological Sciences. 280, doi:10.1098/rspb.2013.0657
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Rates of straying by hatchery-produced Pacific salmon (Oncorhynchus spp.) and steelhead (Oncorhynchus mykiss) differ among species, life history types, and populations Here we ask whether straying differs among species, life history types, and populations of adult hatchery-produced Pacific salmon (Oncorhynchus spp.) and steelhead (Oncorhynchus mykiss) in the Columbia River basin. Previous estimates of straying have been confounded by various factors influencing the probability of individuals returning to non-natal sites (e.g., off- station releases), whereas analyses undertaken here of nearly a quarter million coded-wire tag recoveries control for these factors. Our results revealed large and generally consistent differences in the propensity to stray among species, life history types within species, and populations. Paired releases indicated that (i) Chinook salmon (Oncorhynchus tshawytscha) strayed more (mean population range 0.11%–34.6%) than coho salmon (Oncorhynchus kisutch) (0.08%–0.94%); (ii) ocean-type Chinook (5.2%–18.6%) strayed more than stream- type Chinook (0.11%–10%); and Chinook salmon (0.90%–54.9%) strayed more than steelhead (0.30%–2.3%). We conclude these patterns are largely the result of species- specific behavioral and endocrine factors during the juvenile life stages, but analyses also suggest that environmental factors can influence straying during the adult upstream migration Westley, P. A. H., Quinn, T. P., Dittman, A. H. 2013. Canadian Journal of Fisheries and Aquatic Sciences. 70, 735-746. doi:10.1139/cjfas-2012-0536
A Depth-Based Head-Mounted Visual Display to Aid Navigation in Partially Sighted Individuals Independent navigation for blind individuals can be extremely difficult due to the inability to recognise and avoid obstacles. Assistive techniques such as white canes, guide dogs, and sensory substitution provide a degree of situational awareness by relying on touch or hearing but as yet there are no techniques that attempt to make use of any residual vision that the individual is likely to retain. Residual vision can restricted to the awareness of the orientation of a light source, and hence any information presented on a wearable display would have to limited and unambiguous. For improved situational awareness, i.e. for the detection of obstacles, displaying the size and position of nearby objects, rather than including finer surface details may be sufficient. To test whether a depth-based display could be used to navigate a small obstacle course, we built a real-time head-mounted display with a depth camera and software to detect the distance to nearby objects. Distance was represented as brightness on a low-resolution display positioned close to the eyes without the benefit focussing optics. A set of sighted participants were monitored as they learned to use this display to navigate the course. All were able to do so, and time and velocity rapidly improved with practise with no increase in the number of collisions. In a second experiment a cohort of severely sight-impaired individuals of varying aetiologies performed a search task using a similar low-resolution head-mounted display. The majority of participants were able to use the display to respond to objects in their central and peripheral fields at a similar rate to sighted controls. We conclude that the skill to use a depth-based display for obstacle avoidance can be rapidly acquired and the simplified nature of the display may appropriate for the development of an aid for sight-impaired individuals Hicks, S. L., Wilson, I., Muhammed, L., Worsfold, J., Downes, S. M. & Kennard, C. 2013. PLoS ONE 8, e67695 doi:10.1371/journal.pone.0067695
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High Altitude Bird Migration at Temperate Latitudes: A Synoptic Perspective on Wind Assistance At temperate latitudes the synoptic patterns of bird migration are strongly structured by the presence of cyclones and anticyclones, both in the horizontal and altitudinal dimensions. In certain synoptic conditions, birds may efficiently cross regions with opposing surface wind by choosing a higher flight altitude with more favourable wind. We observed migratory passerines at mid-latitudes that selected high altitude wind optima on particular nights, leading to the formation of structured migration layers at varying altitude up to 3 km. Using long-term vertical profiling of bird migration by C-band Doppler radar in the Netherlands, we find that such migration layers occur nearly exclusively during spring migration in the presence of a high-pressure system. A conceptual analytic framework providing insight into the synoptic patterns of wind assistance for migrants that includes the altitudinal dimension has so far been lacking. We present a simple model for a baroclinic atmosphere that relates vertical profiles of wind assistance to the pressure and temperature patterns occurring at temperate latitudes. We show how the magnitude and direction of the large scale horizontal temperature gradient affects the relative gain in wind assistance that migrants obtain through ascending. Temperature gradients typical for northerly high-pressure systems in spring are shown to cause high altitude wind optima in the easterly sectors of anticyclones, thereby explaining the frequent observations of high altitude migration in these synoptic conditions. Given the recurring synoptic arrangements of pressure systems across temperate continents, the opportunities for exploiting high altitude wind will differ between flyways, for example between easterly and westerly oceanic coasts Dokter, A. M., Shamoun-Baranes, J., Kemp, M. U., Tijm, S. & Holleman, I. 2013. PLoS ONE 8, e52300. doi:10.1371/journal.pone.0052300
The homing frog: High homing performance in a territorial Dendrobatid frog Allobates femoralis (Dendrobatidae) Dendrobatidae (dart-poison frogs) exhibit some of the most complex spatial behaviors among amphibians, such as territoriality and tadpole transport from terrestrial clutches to widely distributed deposition sites. In species that exhibit long-term territoriality, high homing performance after tadpole transport can be assumed, but experimental evidence is lacking, and the underlying orientation mechanisms are unknown. We conducted a field translocation experiment to test whether male Allobates femoralis, a dendrobatid frog with paternal extra-territorial tadpole transport, are capable of homing after experimental removal, as well as to quantify homing success and speed. Translocated individuals showed a very high homing success for distances up to 200 m and successfully returned from up to 400 m. We discuss the potential orientation mechanisms involved and selective forces that could have shaped this strong homing ability. Pasukonis, A., Ringler, M., Brandl, H. B., Mangione, R., Ringler, E., Hödl, W. 2013 Ethology. online early doi: 10.1111/eth.12116
Oceanic navigation in Cory's shearwaters: evidence for a crucial role of olfactory cues for homing after displacement Pelagic birds, which wander in the open sea most of the year and often nest on small remote oceanic islands, are able to pinpoint their breeding colony even within an apparently featureless environment, such as the open ocean. The mechanisms underlying their surprising navigational performance are still unknown. In order to investigate the nature of the cues exploited for oceanic navigation, Cory's shearwaters, Calonectris borealis, nesting in
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the Azores were displaced and released in open ocean at about 800 km from their colony, after being subjected to sensory manipulation. While magnetically disturbed shearwaters showed unaltered navigational performance and behaved similarly to unmanipulated control birds, the shearwaters deprived of their sense of smell were dramatically impaired in orientation and homing. Our data show that seabirds use olfactory cues not only to find their food but also to navigate over vast distances in the ocean Gagliardo, A., Bried, J., Lambardi, P., Luschi, P., Wikelski, M., Bonadonna, F. 2013 The Journal of Experimental Biology. 216, 2798-2805. doi: 10.1242/jeb.085738
Ocean navigation: smelling your way home 1st para. There are no mountains or other visual landmarks in the middle of the Atlantic Ocean, and if you find yourself without a map or GPS, chances are it’s not going to be easy finding your way home. However, for a Cory’s shearwater, navigation in this featureless environment is just another run-of-the-mill exercise. These birds spend most of their lives wandering the oceans, but every year they will return to the same small island to breed. Although it’s like finding a needle in a haystack, these birds have no trouble. So, how do they do it? It’s a question that fascinates Anna Gagliardo, from the University of Pisa, Italy. She explains that there are two potential cues that could aid their long-haul flights – their sense of smell or the natural geomagnetic field. But which cue is it? In collaboration with the researchers from her own university as well as the University of the Azores, Portugal, the Max Planck Institute for Ornithology, Germany, and the CNRS/CEFE, France, Gagliardo visited a colony of breeding Cory’s shearwaters on the remote Portuguese Azores archipelago to find out how shearwaters made it back to their colony after being displaced Stead, N. 2013. The Journal of Experimental Biology. 216, doi: 10.1242/jeb.090555
Directional compass preference for landing in water birds INTRODUCTION: Landing flight in birds is demanding on visual control of velocity, distance to target, and slope of descent. Birds flying in flocks must also keep a common course of landing in order to avoid collisions. Whereas the wind direction may provide a cue for landing, the nature of the landing direction indicator under windless conditions has been unknown. We recorded and analysed landing directions of 3,338 flocks in 14 species of water birds in eight countries. RESULTS: We show that the preferred landing direction, independently of the direction from which the birds have arrived, is along the north-south axis. We analysed the effect of the time of the year, time of the day (and thus sun position), weather (sunny versus overcast), light breeze, locality, latitude, and magnetic declination in 2,431 flocks of mallards (Anas platyrhynchos) and found no systematic effect of these factors upon the preferred direction of landing. We found that magnetic North was a better predictor for landing direction than geographic North. CONCLUSIONS: In absence of any other common denominator determining the landing direction, the alignment with the magnetic field lines seems to be the most plausible if not the only explanation for the directional landing preference under windless and overcast conditions and we suggest that the magnetic field thus provides a landing direction indicator. Hart, V., Malkemper, E.P., Kusta, T., Begall, S., Novakova, P., Pleskac, L., Jezek, M., Husinec, V., Cerveny, J., Burda, H. 2013. Frontiers in Zoology. 10, 38. doi: 0.1186/1742-9994-10-38
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Ant foraging and geodesic paths in labyrinths: Analytical and computational results In this paper we propose a mechanism for the formation of paths of minimal length between two points (trails) by a collection of individuals undergoing reinforced random walks. This is the case, for instance, of ant colonies in search for food and the development of ant trails connecting nest and food source. Our mechanism involves two main ingredients: (1) the reinforcement due to the gradients in the concentration of some substance (pheromones in the case of ants) and (2) the persistence understood as the tendency to preferably follow straight directions in the absence of any external effect. Our study involves the formulation and analysis of suitable Markov chains for the motion in simple labyrinths, that will be understood as graphs, and numerical computations in more complex graphs reproducing experiments performed in the past with ants. Vela-Pérez, M., Fontelos, M. A., Velazquez, J. J. L. 2013. Journal of Theoretical Biology. 320, 100-112.
Selection pressures give composite correlated random walks Lévy walk characteristics Composite correlated random walks have been posited as a strong alternative to Lévy walks as models of multi-scale forager movement patterns. Here it is shown that if plastic then intrinsic composite correlated random walks will, under selection pressures, evolve to resemble optimal Lévy walks when foraging is non-destructive. The fittest composite correlated random walkers are found to be those that come closest to being optimal Lévy walkers. This may explain why such a diverse range of foragers have movement patterns that can be approximated by optimal Lévy walks and shows that the 'Lévy-flight foraging' hypothesis has a broad hinterland. The new findings are consistent with recent observations of mussels Mytilus edulis and the Australian desert ant Melophorus bagoti which suggest that animals approximate a Lévy walk by adopting an intrinsic composite movement strategy with different modes Reynolds, A. M. 2013. Journal of Theoretical Biology. 332, 117-122. doi: 10.1016/j.jtbi.2013.04.035
Exploring juvenile golden eagles' dispersal movements at two different temporal scales The spatial distribution of populations is the result of individuals' movements. In territorial species, the spatial dynamics of populations is to a large degree shaped by individuals' ranging behaviour during their juvenile dispersal. Here we use information on juvenile golden eagles (Aquila chrysaetos) tracked by satellite telemetry, to explore the effects of daily behavioural decisions on their dispersal strategy during their first year of life. When analysed on a biweekly basis, the large-scale movements of golden eagles did not differ from a correlated random walk (CRW) model of dispersal. Although in the long term such a strategy maximises the acquisition of information on good hunting areas, finding a mate and a vacant territory in a landscape, it is expensive in terms of energy requirements. At the finer scale of daily foraging movements, movement patterns were non-random, probably reflecting animals' oriented movements towards sites with high chances of successful hunting. We suggest that the key issue to take into account when exploring the factors determining individuals' dispersal strategies is how strongly the daily movements are influenced by an active search for food. This is to a large degree determined by food availability and individuals' ability to accumulate reserves. In our case, the individuals with the lowest proportion of foraging habitats within their dispersal areas showed large-scale movements
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more restricted than expected from a CRW. Also, distances covered by individuals in their biweekly movements were both larger and more variable in winter, when food availability diminishes The spatial distribution of populations is the result of individuals' movements. In territorial species, the spatial dynamics of populations is to a large degree shaped by individuals' ranging behaviour during their juvenile dispersal. Here we use information on juvenile golden eagles (Aquila chrysaetos) tracked by satellite telemetry, to explore the effects of daily behavioural decisions on their dispersal strategy during their first year of life. When analysed on a biweekly basis, the large-scale movements of golden eagles did not differ from a correlated random walk (CRW) model of dispersal. Although in the long term such a strategy maximises the acquisition of information on good hunting areas, finding a mate and a vacant territory in a landscape, it is expensive in terms of energy requirements. At the finer scale of daily foraging movements, movement patterns were non-random, probably reflecting animals' oriented movements towards sites with high chances of successful hunting. We suggest that the key issue to take into account when exploring the factors determining individuals' dispersal strategies is how strongly the daily movements are influenced by an active search for food. This is to a large degree determined by food availability and individuals' ability to accumulate reserves. In our case, the individuals with the lowest proportion of foraging habitats within their dispersal areas showed large-scale movements more restricted than expected from a CRW. Also, distances covered by individuals in their biweekly movements were both larger and more variable in winter, when food availability diminishes. Soutullo, A., Lopez-Lopez, P., Corte, G. D., Urios, V., Ferrer, M. 2013. Ethology Ecology & Evolution. 25, 117-128. doi:10.1080/03949370.2012.742463
Seasonal differences in behavior patterns of the migratory white-throated sparrow Avian migration and associated changes in behavior patterns occur on a seasonal basis and are regulated by both circadian and circannual clocks. It is well known that seasonally migrating birds must alter the temporal partitioning of behaviors in order to successfully complete nocturnal migration, although the precise changes in allocation have not previously been examined. Because of the difficulties related to the study of bird migration in the wild, many studies regarding the physiology of migration have been performed in captivity, where nocturnal migratory restlessness is readily observable at the appropriate times of the year. Even so, quantifying the amount and timing of daily behavioral rhythms in migrating and non- migrating individuals has not previously been performed. We used video recordings of a common nocturnal migrant, the white-throated sparrow (Zonotrichia albicollis), to generate a basic ethogram and to chart the timing and frequency of occurrence of each behavior in order to compare migrant individuals with non-migrating birds. Our study suggests that the specific allocation of behaviors are altered during migration and that these changes might contribute to the development of the "migratory syndrome". Stuber, E. F., Bartell, P. A. 2013. Journal for Ethology 31, 151-158 doi:10.1007/s10164-013-0361-5
High-altitude migration of Heteroptera in Britain Heteroptera caught during day and night sampling at a height of 200 m above ground at Cardington, Bedfordshire, UK, during eight summers (1999, 2000, and 2002–2007) were compared to high-altitude catches made over the UK and North Sea from the 1930s to the 1950s. The height of these captures indicates that individuals were engaged in windborne
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migration over distances of at least several kilometres and probably tens of kilometres. This conclusion is generally supported by what is known of the species' ecologies, which reflect the view that the level of dispersiveness is associated with the exploitation of temporary habitats or resources. The seasonal timing of the heteropteran migrations is interpreted in terms of the breeding/overwintering cycles of the species concerned. Reynolds, D. R., Nau, B. S., Chapman, J. W. 2013 European Journal of Entomology. 110, 483-492 http://www.eje.cz/pdfs/110/3/483
Flying at No Mechanical Energy Cost: Disclosing the Secret of Wandering Albatrosses Albatrosses do something that no other birds are able to do: fly thousands of kilometres at no mechanical cost. This is possible because they use dynamic soaring, a flight mode that enables them to gain the energy required for flying from wind. Until now, the physical mechanisms of the energy gain in terms of the energy transfer from the wind to the bird were mostly unknown. Here we show that the energy gain is achieved by a dynamic flight manoeuvre consisting of a continually repeated up-down curve with optimal adjustment to the wind. We determined the energy obtained from the wind by analysing the measured trajectories of free flying birds using a new GPS-signal tracking method yielding a high precision. Our results reveal an evolutionary adaptation to an extreme environment, and may support recent biologically inspired research on robotic aircraft that might utilize albatrosses' flight technique for engineless propulsion Sachs, G., Traugott, J., Nesterova, A. P., Dell'Omo, G., Kümmeth , F., Heidrich, W., Vyssotski, A. L. & Bonadonna, F. 2012. PLoS ONE 7, e41449. doi:10.1371/journal.pone.0041449
Scouts behave as streakers in honeybee swarms Harmonic radar tracking was used to record the flights of scout bees during takeoff and initial flight path of two honeybee swarms. One swarm remained intact and performed a full flight to a destination beyond the range of the harmonic radar, while a second swarm disintegrated within the range of the radar and most of the bees returned to the queen. The initial stretch of the full flight is characterized by accelerating speed, whereas the disintegrating swarm flew steadily at low speed. The two scouts in the swarm displaying full flight performed characteristic flight maneuvers. They flew at high speed when traveling in the direction of their destination and slowed down or returned over short stretches at low speed. Scouts in the disintegrating swarm did not exhibit the same kind of characteristic flight performance. Our data support the streaker bee hypothesis proposing that scout bees guide the swarm by traveling at high speed in the direction of the new nest site for short stretches of flight and slowing down when reversing flight direction Greggers, U., Schöning, C., Degen, J. & Menzel, R. 2013. Naturwissenschaften 100, 805-809. doi: 10.1007/s00114-013-1077-7
Air speeds of migrating birds observed by ornithodolite and compared with predictions from flight theory We measured the air speeds of 31 bird species, for which we had body mass and wing measurements, migrating along the east coast of Sweden in autumn, using a Vectronix Vector 21 ornithodolite and a Gill WindSonic anemometer. We expected each species’ average air speed to exceed its calculated minimum-power speed (Vmp), and to fall below its maximum-range speed (Vmr), but found some exceptions to both limits. To resolve these discrepancies, we first reduced the assumed induced power factor for all species from
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1.2 to 0.9, attributing this to splayed and up-turned primary feathers, and then assigned body drag coefficients for different species down to 0.060 for small waders, and up to 0.12 for the mute swan, in the Reynolds number range 25 000-250 000. These results will be used to amend the default values in existing software that estimates fuel consumption in migration, energy heights on arrival and other aspects of flight performance, using classical aeronautical theory. The body drag coefficients are central to range calculations. Although they cannot be measured on dead bird bodies, they could be checked against wind tunnel measurements on living birds, using existing methods Pennycuick, C. J., Akesson, S., Hedenström, A. 2013. Journal of The Royal Society Interface. 10, doi: 10.1098/rsif.2013.0419
Travelling light: white sharks (Carcharodon carcharias) rely on body lipid stores to power ocean-basin scale migration Many species undertake long-distance annual migrations between foraging and reproductive areas. Such migrants depend on the efficient packaging, storage and utilization of energy to succeed. A diverse assemblage of organisms accomplishes this through the use of lipid reserves; yet, it remains unclear whether the migrations of elasmobranchs, which include the largest gill breathers on Earth, depend on such a mechanism. We examine depth records from pop-up satellite archival tags to discern changes in buoyancy as a proxy for energy storage in Eastern Pacific white sharks, and assess whether lipid depletion fuels long- distance (approx. 4000 km) migrations. We develop new algorithms to assess body condition, buoyancy and drift rate during drift dives and validate the techniques using a captive white shark. In the wild, we document a consistent increase in drift rate over the course of all migrations, indicating a decrease in buoyancy caused by the depletion of lipid reserves. These results comprise, to our knowledge, the first assessment of energy storage and budgeting in migrating sharks. The methods provide a basis for further insights into using electronic tags to reveal the energetic strategies of a wide range of elasmobranches Del Raye, G., Jorgensen, S. J., Krumhansl, K., Ezcurra, J. M., Block, B. A. 2013. Proceedings of the Royal Society B: Biological Sciences. 280 doi:10.1098/rspb.2013.0836
Are Lévy flight patterns derived from the Weber-Fechner law in distance estimation? Honeybees (Apis mellifera) are regularly faced with the task of navigating back to their hives from remote food sources. They have evolved several methods to do this, including compass-directed "vector" flights and the use of landmarks. If these hive-centered mechanisms are disrupted, bees revert to searching for the hive, using an optimal Lévy flight searching strategy. The same strategy is adopted when a food source at a known location ceases to be available. Here, we show that the programming for this Lévy strategy does not need to be very sophisticated or clever on the bee's part, as Lévy flight patterns can be derived from the Weber-Fechner law in a bee's odometer. Odometry errors of a different kind occur in desert ants (Cataglyphis spp., Melophorus bagoti). The searching behaviors of these ants are very similar in overall structure to that of honeybees but do not display any Lévy flight characteristics. We suggest that errors in the estimation of distance can be implicitly involved in shaping the structure of systematic search behavior and should not be regarded as merely deficiencies in the odometer Reynolds, A. M., Schultheiss, P., Cheng, K. 2013 Behav Ecol Sociobiology. 67, 1219- 1226. doi: 10.1007/s00265-013-1549-y
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The Head-Direction Signal Is Critical for Navigation Requiring a Cognitive Map but Not for Learning a Spatial Habit Head-direction (HD) cells fire as a function of an animal s directional heading in the horizontal plane during two-dimensional navigational tasks [1]. The information from HD cells is used with place and grid cells to form a spatial representation (cognitive map) of the environment [2, 3]. Previous studies have shown that when rats are inverted (upside down), they have difficulty learning a task that requires them to find an escape hole from one of four entry points but that they can learn it when released from one or two start points [4]. Previous reports also indicate that the HD signal is disrupted when a rat is oriented upside down [5, 6]. Here we monitored HD cell activity in the two-entry-point version of the inverted task and when the rats were released from a novel start point. We found that despite the absence of direction-specific firing in HD cells when inverted, rats could successfully navigate to the escape hole when released from one of two familiar locations by using a habit-associated directional strategy. In the continued absence of normal HD cell activity, inverted rats failed to find the escape hole when started from a novel release point. The results suggest that the HD signal is critical for accurate navigation in situations that require a flexible allocentric cognitive mapping strategy, but not for situations that utilize habit-like associative spatial learning. "We recorded HD cells from rats while inverted moving from familiar or novel locations"Direction-specific firing was disrupted after release from both conditions"Rats navigated accurately from the familiar, but not from the novel release points"Navigation using a flexible representation of space requires a functional HD signal Gibson, B., Butler, William N. & Taube, Jeffery S. 2013 Current biology : CB. doi: 10.1016/j.cub.2013.06.030
Pectoral fins aid in navigation of a complex environment by bluegill sunfish under sensory deprivation conditions Complex structured environments offer fish advantages as places of refuge and areas of greater potential prey densities, but maneuvering through these environments is a navigational challenge. To successfully navigate complex habitats, fish must have sensory input relaying information about the proximity and size of obstacles. We investigated the role of the pectoral fins as mechanosensors in bluegill sunfish swimming through obstacle courses under different sensory deprivation and flow speed conditions. Sensory deprivation was accomplished by filming in the dark to remove visual input and/or temporarily blocking lateral line input via immersion in cobalt chloride. Fish used their pectoral fins to touch obstacles as they swam slowly past them under all conditions. Loss of visual and/or lateral line sensory input resulted in an increased number of fin taps and shorter tap durations while traversing the course. Propulsive pectoral fin strokes were made in open areas between obstacle posts and fish did not use the pectoral fins to push off or change heading. Bending of the flexible pectoral fin rays may initiate an afferent sensory input, which could be an important part of the proprioceptive feedback system needed to navigate complex environments. This behavioral evidence suggests that it is possible for unspecialized pectoral fins to act in both a sensory and a propulsive capacity. Flammang, B. E., Lauder, G. V. 2013. The Journal of Experimental Biology. 216, 3084- 3089. doi: 10.1242/jeb.080077
Ontogenetic development of magnetic compass orientation in domestic chickens (Gallus gallus) Domestic chickens (Gallus gallus) can be trained to search for a social stimulus in a specific
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magnetic direction, and cryptochrome 1a, found in the retina, has been proposed as a receptor molecule mediating magnetic directions. The present study combines immuno- histochemical and behavioural data to analyse the ontogenetic development of this ability. Newly hatched chicks already have a small amount of cryptochrome 1a in their violet cones; on day 5, the amount of cryptochrome 1a reached the same level as in adult chickens, suggesting that the physical basis for magnetoreception is present. In behavioural tests, however, young chicks 5 to 7 days old failed to show a preference of the training direction; on days 8, 9 and 12, they could be successfully trained to search along a specific magnetic axis. Trained and tested again 1 week later, the chicks that had not shown a directional preference on days 5 to 7 continued to search randomly, while the chicks tested from day 8 onward preferred the correct magnetic axis when tested 1 week later. The observation that the magnetic compass is not functional before day 8 suggests that certain maturation processes in the magnetosensitive system in the brain are not yet complete before that day. The reasons why chicks that have been trained before that day fail to learn the task later remain unclear Denzau, S., Nießner, C., Rogers, L. J., Wiltschko, W. 2013 The Journal of Experimental Biology. 216, 3143-3147. doi: 10.1242/jeb.088815
Group recruitment in a thermophilic desert ant, Ocymyrmex robustior Thermophilic desert ants—Cataglyphis, Ocymyrmex, and Melophorus species inhabiting the arid zones of the Palaearctic region, southern Africa and central Australia, respectively—are solitary foragers, which have been considered to lack any kind of chemical recruitment. Here we show that besides mainly employing the solitary mode of food retrieval Ocymyrmex robustior regularly exhibits group recruitment to food patches that cannot be exploited individually. Running at high speed to recruitment sites that may be more than 60 m apart from the nest a leading ant, the recruiter, is followed by a loose and often quite dispersed group of usually 2–7 recruits, which often overtake the leader, or may lose contact, fall back and return to the nest. As video recordings show the leader, while continually keeping her gaster in a downward position, intermittently touches the surface of the ground with the tip of the gaster most likely depositing a volatile pheromone signal. These recruitment events occur during the entire diurnal activity period of the Ocymyrmex foragers, that is, even at surface temperatures of more than 60 °C. They may provide promising experimental paradigms for studying the interplay of orientation by chemical signals and path integration as well as other visual guidance routines. Sommer, S., Weibel, D., Blaser, N., Furrer, A., Wenzler, N., Roessler, W. & Wehner, R. 2013 Group recruitment in a thermophilic desert ant, Ocymyrmex robustior. Journal of Comparative Physiology A 199, 711-722. doi: 10.1007/s00359-013-0830-x
Intra- and inter-individual variation in flight direction in a migratory butterfly co- vary with individual mobility Flight direction is a major component of an animal's migratory success. However, few studies have focused on variation in flight direction both between and within individuals, which is likely to be correlated with other traits implied in migration processes. We report patterns of intra- and inter-individual variation in flight direction in the large white butterfly Pieris brassicae. The presence of inter-individual variation in flight direction for individuals tested in the same conditions suggests that this trait is inherited in P. brassicae and we propose that a rapid loss of migratory skills may exist in the absence of selection for migration. The magnitude of intra-individual variation was negatively correlated to two surrogates of the potential for migration: mobility and wing length. Highly mobile and
55 longed-winged individuals within the same family were found to fly in similar directions, whereas less mobile and short-winged individuals displayed divergent flight direction compared with the average direction of their kin. There was also a negative correlation between the variance to the mean flight direction of a family and its average mobility, but no correlation with wing length. We discuss these issues in terms of the evolution of traits potentially implied in both migration and dispersal in P. brassicae. Flight direction is a major component of an animal's migratory success. However, few studies have focused on variation in flight direction both between and within individuals, which is likely to be correlated with other traits implied in migration processes. We report patterns of intra- and inter-individual variation in flight direction in the large white butterfly Pieris brassicae. The presence of inter-individual variation in flight direction for individuals tested in the same conditions suggests that this trait is inherited in P. brassicae and we propose that a rapid loss of migratory skills may exist in the absence of selection for migration. The magnitude of intra-individual variation was negatively correlated to two surrogates of the potential for migration: mobility and wing length. Highly mobile and longed-winged individuals within the same family were found to fly in similar directions, whereas less mobile and short-winged individuals displayed divergent flight direction compared with the average direction of their kin. There was also a negative correlation between the variance to the mean flight direction of a family and its average mobility, but no correlation with wing length. We discuss these issues in terms of the evolution of traits potentially implied in both migration and dispersal in P. brassicae. Larranaga, N., Baguette, M., Calvez, O., Trochet, A., Ducatez, S. & Legrand, D. 2013. The Journal of Experimental Biology 216, 3156-3163. doi:10.1242/jeb.082883
Learning of Multi-Modal Stimuli in Hawkmoths The hawkmoth, Manduca sexta, uses both colour and odour to find flowers when foraging for nectar. In the present study we investigated how vision and olfaction interact during learning. Manduca sexta were equally attracted to a scented blue coloured feeding target (multimodal stimulus) as to one that does not carry any scent (unimodal stimulus; visual) or to an invisible scented target (unimodal stimulus; odour). This naive attraction to multimodal as well as to unimodal stimuli could be manipulated through training. Moths trained to feed from a blue, scented multimodal feeding target will, when tested in a set-up containing all three feeding targets, select the multimodal target as well as the scented, unimodal target, but ignore the visual target. Interestingly, moths trained to feed from a blue, unimodal visual feeding target will select the visual target as well as the scented, multimodal target, but ignore the unimodal odour target. Our results indicate that a multimodal target is perceived as two separate modalities, colour and odour, rather than as a unique fused target. These findings differ from earlier studies of desert ants that perceive combined visual and odour signals as a unique fused stimulus following learning trials. The hawkmoth, Manduca sexta, uses both colour and odour to find flowers when foraging for nectar. In the present study we investigated how vision and olfaction interact during learning. Manduca sexta were equally attracted to a scented blue coloured feeding target (multimodal stimulus) as to one that does not carry any scent (unimodal stimulus; visual) or to an invisible scented target (unimodal stimulus; odour). This naive attraction to multimodal as well as to unimodal stimuli could be manipulated through training. Moths trained to feed from a blue, scented multimodal feeding target will, when tested in a set-up containing all three feeding targets, select the multimodal target as well as the scented, unimodal target, but ignore the visual target. Interestingly, moths trained to feed from a blue, unimodal visual feeding target will select the visual target as well as the scented, multimodal target, but ignore the unimodal odour target. Our results indicate that a multimodal target is perceived 56
as two separate modalities, colour and odour, rather than as a unique fused target. These findings differ from earlier studies of desert ants that perceive combined visual and odour signals as a unique fused stimulus following learning trials. Balkenius, A. & Dacke, M. 2013. PLoS ONE 8, e71137. doi:10.1371/journal.pone.0071137
Assignment tests, telemetry and tag-recapture data converge to identify natal origins of leatherback turtles foraging in Atlantic Canadian waters Investigating migratory connectivity between breeding and foraging areas is critical to effective management and conservation of highly mobile marine taxa, particularly threatened, endangered, or economically important species that cross through regional, national and international boundaries. * The leatherback turtle (Dermochelys coriacea, Vandelli 1761) is one such transboundary species that spends time at breeding areas at low latitudes in the northwest Atlantic during spring and summer. From there, they migrate widely throughout the North Atlantic, but many show fidelity to one region off eastern Canada, where critical foraging habitat has been proposed. Our goal was to identify nesting beach origins for turtles foraging here. * Using genetics, we identified natal beaches for 288 turtles that were live-captured off the coast of Nova Scotia, Canada. Turtles were sampled (skin or blood) and genotyped using 17 polymorphic microsatellite markers. Results from three assignment testing programs (ONCOR, GeneClass2 and Structure) were compared. Our nesting population reference data set included 1417 individuals from nine Atlantic nesting assemblages. A supplementary data set for 83 foraging turtles traced to nesting beaches using flipper tags and/or PIT tags (n = 72), or inferred from satellite telemetry (n = 11), enabled ground-truthing of the assignments. * We first assigned turtles using only genetic information and then used the supplementary recapture information to verify assignments. ONCOR performed best, assigning 64 of the 83 recaptured turtles to natal beaches (77·1%). Turtles assigned to Trinidad (164), French Guiana (72), Costa Rica (44), St. Croix (7), and Florida (1) reflect the relative size of those nesting populations, although none of the turtles were assigned to four other potential source nesting assemblages. * Our results demonstrate the utility of genetic approaches for determining source populations of foraging marine animals and include the first identification of natal rookeries of male leatherbacks, identified through satellite telemetry and verified with genetics. This work highlights the importance of long-term monitoring and tagging programmes in nesting and high-use foraging areas. Moreover, it provides a scientific basis for evaluating stock-specific effects of fisheries on migratory marine species, thus identifying where coordinated international recovery efforts may be most effective Stewart, K. R., James, M. C., Roden, S. & Dutton, P. H. 2013. Journal of Animal Ecology 82, 791-803. doi: 10.1111/1365-2656.12056
Timing of songbird migration: individual consistency within and between seasons The timing of migration is generally considered of utmost importance for reproduction and survival, and timing is furthermore considered to be under strong genetic control. The individual timing of migration is presumably a result of a combination of genetic, phenotypic and environmental factors as well as some degree of randomness. However, potential differences in consistency of timing between spring and autumn and between migration strategies are not well studied. Using long-term Danish ringing data, we study such differences by correlating date of ringing with date of recaptures for a suite of common migrating passerines in Denmark. We found that individuals marked early in one year tended to be recaptured early in the same season in a following year indicating that individuals time
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their migration in spring or autumn similarly between years. The relationship between spring and autumn migration was overall slightly negative, suggesting that birds arriving early in spring tended to depart late in autumn and vice versa. There were only weak effects of geographical location on timing, suggesting that the patterns found are not primarily caused by different populations being involved. Knowledge of individual consistency in migration timing is needed for understanding changes in migration timing. The consistent patterns of repeatabilities within and between seasons found here highlight the importance of timing of migration in songbirds Thorup, K., Vardanis, Y., Tøttrup, A. P., Kristensen, M. W., Alerstam, T. 2013 Journal of Avian Biology. early view, doi: 10.1111/j.1600-048X.2013.05871.x
Satellite telemetry reveals long-distance migration in the Asian great bustard Otis tarda dybowski The range of the great bustard stretches 10 000 km across Eurasia, one of the largest ranges of any threatened species. While movement patterns of the western subspecies of great bustard are relatively well-understood, this is the first research to monitor the movements of the more endangered Asian subspecies of great bustard through telemetry and to link a breeding population of Asian great bustards to their wintering grounds. Using Argos/GPS platform transmitter terminals, we identified the annual movement patterns of three female great bustards captured at their breeding sites in northern Mongolia. The 4000 km round- trip migration we have recorded terminated at wintering grounds in Shaanxi, China. This route is twice as long as has previously been reported for great bustards, which are among the heaviest flying birds. The journey was accomplished in approximately two months each way, at ground velocities of 48–98 km h−1, and incorporated multiple and variable stopover sites. On their wintering grounds these birds moved itinerantly across relatively large home ranges. Our findings confirm that migratory behavior in this species varies longitudinally. This variation may be attributable to longitudinal gradients in seasonality and severity of winter across Eurasia. The distance and duration of the migratory route taken by great bustards breeding in Mongolia, the crossing of an international border, the incorporation of many stopovers, and the use of a large wintering territory present challenges to the conservation of the Asian subspecies of great bustard in this rapidly changing part of the world Kessler, A. E., Batbayar, N., Natsagdorj, T., Batsuur’, D. & Smith, A. T. 2013 Journal of Avian Biology 44, 311-320 doi: 10.1111/j.1600-048X.2013.00072.x
Tracking multi-generational colonization of the breeding grounds by monarch butterflies in eastern North America Insect migration may involve movements over multiple breeding generations at continental scales, resulting in formidable challenges to their conservation and management. Using distribution models generated from citizen scientist occurrence data and stable-carbon and - hydrogen isotope measurements, we tracked multi-generational colonization of the breeding grounds of monarch butterflies (Danaus plexippus) in eastern North America. We found that monarch breeding occurrence was best modelled with geographical and climatic variables resulting in an annual breeding distribution of greater than 12 million km2 that encompassed 99% occurrence probability. Combining occurrence models with stable isotope measurements to estimate natal origin, we show that butterflies which overwintered in Mexico came from a wide breeding distribution, including southern portions of the range. There was a clear northward progression of monarchs over successive generations from May until August when reproductive butterflies began to change direction and moved south.
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Fifth-generation individuals breeding in Texas in the late summer/autumn tended to originate from northern breeding areas rather than regions further south. Although the Midwest was the most productive area during the breeding season, monarchs that re-colonized the Midwest were produced largely in Texas, suggesting that conserving breeding habitat in the Midwest alone is insufficient to ensure long-term persistence of the monarch butterfly population in eastern North America. Flockhart, D. T. T., Wassenaar, L. I., Martin, T. G., Hobson, K. A., Wunder, M. B., Norris, D. R. 2013. Proceedings of the Royal Society B: Biological Sciences. 280, doi: 10.1098/rspb.2013.1087
Do naive juvenile seabirds forage differently from adults? Foraging skills of young individuals are assumed to be inferior to those of adults. The reduced efficiency of naive individuals may be the primary cause of the high juvenile mortality and explain the deferment of maturity in long-lived species. However, the study of juvenile and immature foraging behaviour has been limited so far. We used satellite telemetry to compare the foraging movements of juveniles, immatures and breeding adult wandering albatrosses Diomedea exulans, a species where foraging success is positively influenced by the distance covered daily. We showed that juveniles are able to use favourable winds as soon as the first month of independence, but cover shorter distances daily and spend more time sitting on water than adults during the first two months after fledging. These reduced movement capacities do not seem to be the cause of higher juvenile mortality. Moreover, juveniles almost never restrict their movement to specific areas, as adults and immatures frequently do over shelf edges or oceanic zones, which suggest that the location of appropriate areas is learned through experience. Immatures and adults have equivalent movement capacities, but when they are central place foragers, i.e. when adults breed or immatures come to the colony to display and pair, immatures make shorter trips than adults. The long duration of immaturity in this species seems to be related to a long period of learning to integrate the foraging constraints associated with reproduction and central place foraging. Our results indicate that foraging behaviour of young albatrosses is partly innate and partly learned progressively over immaturity. The first months of learning appear critical in terms of survival, whereas the long period of immaturity is necessary for young birds to attain the skills necessary for efficient breeding without fitness costs Riotte-Lambert, L., Weimerskirch, H. 2013 Proceedings of the Royal Society B: Biological Sciences. 280, doi: 10.1098/rspb.2013.1434
Do sandhoppers use the skylight polarization as a compass cue? Investigations carried out in the 1950s on the use of polarized light by sandhoppers as a compass reference did not reach convincing results. Therefore, polarized light compass orientation in the sandhopper Talitrus saltator seems to be a traditional attribute more than a solid demonstration. Our tests carried out under artificial and natural conditions of illumination using different polarizing and neutral density (grey) filters demonstrated that T. saltator perceives polarized light; however, it does not use the skylight polarized light as a cue for menotactic orientation. However, since the sky spectral and luminance gradients were not completely eliminated in our tests, a possible influence of these two celestial factors of orientation could still be present. Therefore, we conclude that this species, in this experimental paradigm at least, does not use a polarized light compass mechanism, despite a very good sun compass system of orientation. Ugolini, A., Galanti, G., Mercatelli, L. 2013 Animal Behaviour. 86, 427-434. http://dx.doi.org/10.1016/j.anbehav.2013.05.037
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Direct recordings of grid-like neuronal activity in human spatial navigation Grid cells in the entorhinal cortex appear to represent spatial location via a triangular coordinate system. Such cells, which have been identified in rats, bats and monkeys, are believed to support a wide range of spatial behaviors. Recording neuronal activity from neurosurgical patients performing a virtual-navigation task, we identified cells exhibiting grid- like spiking patterns in the human brain, suggesting that humans and simpler animals rely on homologous spatial-coding schemes. Jacobs, J., Weidemann, C. T., Miller, J. F., Solway, A., Burke, J. F., Wei, X. X., Suthana, N., Sperling, M. R., Sharan, A. D., Fried, I., Kahana, M. J. 2013. Nat Neurosci. advanced online publication. doi: 10.1038/nn.3466
Mapping Global Diversity Patterns for Migratory Birds Nearly one in five bird species has separate breeding and overwintering distributions, and the regular migrations of these species cause a substantial seasonal redistribution of avian diversity across the world. However, despite its ecological importance, bird migration has been largely ignored in studies of global avian biodiversity, with few studies having addressed it from a macroecological perspective. Here, we analyse a dataset on the global distribution of the world's birds in order to examine global spatial patterns in the diversity of migratory species, including: the seasonal variation in overall species diversity due to migration; the contribution of migratory birds to local bird diversity; and the distribution of narrow-range and threatened migratory birds. Our analyses reveal a striking asymmetry between the Northern and Southern hemispheres, evident in all of the patterns investigated. The highest migratory bird diversity was found in the Northern Hemisphere, with high inter-continental turnover in species composition between breeding and non-breeding seasons, and extensive regions (at high latitudes) where migratory birds constitute the majority of the local avifauna. Threatened migratory birds are concentrated mainly in Central and Southern Asia, whereas narrow-range migratory species are mainly found in Central America, the Himalayas and Patagonia. Overall, global patterns in the diversity of migratory birds indicate that bird migration is mainly a Northern Hemisphere phenomenon. The asymmetry between the Northern and Southern hemispheres could not have easily been predicted from the combined results of regional scale studies, highlighting the importance of a global perspective Somveille, M., Manica, A., Butchart, S. H. M. & Rodrigues, A. S. L. 2013. PLoS ONE 8, e70907 doi:10.1371/journal.pone.0070907
Comparative analysis of olfactory learning of Apis cerana and Apis mellifera The Eastern honeybee, Apis cerana, is indigenous to Asia and is an important pollinator for Asian ecosystems; the Western honeybee, Apis mellifera, has been introduced to Asia because of its high honey yields. These two species are now sympatric and share a similar environment. Whether learning in A. cerana can be studied using the proboscis extension response paradigm, as developed for A. mellifera, is still unexplored. Here, we investigate A. cerana’s associative olfactory learning with three different odors (hexanal, nonanal, and geraniol) and compared it with the learning performances of A. mellifera. After an acquisition phase, the bees were tested to determine whether they discriminated between the experienced odors (an odor paired with a reward during acquisition) from non-experienced odors (an odor not paired with a reward during acquisition). During the acquisition phase, A. mellifera showed higher learning scores than A. cerana. However, there was no statistical difference between the two species in the retention phase. Both species discriminated an experienced odor from a non-experienced odor. Our results suggested that A. cerana is
60 equally amenable to the study of learning using the proboscis extension response paradigm supporting the behavioral evidence for future olfactory learning research with A. cerana. Wang, Z. & Tan, K. 2013. Apidologie Online First, 1-8. doi: 10.1007/s13592-013- 0228-3
A radical sense of direction: signalling and mechanism in cryptochrome magnetoreception The remarkable phenomenon of magnetoreception in migratory birds and other organisms has fascinated biologists for decades. Much evidence has accumulated to suggest that birds sense the magnetic field of the Earth using photochemical transformations in cryptochrome flavoproteins. In the last 5 years this highly interdisciplinary field has seen advances in structural biology, biophysics, spin chemistry, and genetic studies in model organisms. We review these developments and consider how this chemical signal can be integrated into the cellular response. Dodson, C. A., Hore, P. J., Wallace, M. I. 2013 Trends in Biochemical Sciences. online early, doi:10.1016/j.tibs.2013.07.002
Predicting the distribution of oceanic-stage Kemp's ridley sea turtles The inaccessibility of open ocean habitat and the cryptic nature of small animals are fundamental problems when assessing the distribution of oceanic-stage sea turtles and other marine animals sharing similar life-history traits. Most methods that estimate patterns of abundance cannot be applied in situations that are extremely data limited. Here, we use a movement ecology framework to generate the first predicted distributions for the oceanic stage of the Kemp's ridley sea turtle (Lepidochelys kempii). Our simulations of particle dispersal within ocean circulation models reveal substantial annual variation in distribution and survival among simulated cohorts. Such techniques can help prioritize areas for conservation, and supply inputs for more realistic demographic models attempting to characterize population trends Putman, N. F., Mansfield, K. L., He, R., Shaver, D. J., Verley, P. 2013 Biology Letters. 9, doi: 10.1098/rsbl.2013.0345
Acknowledgement Special thank-you’s to Dr M Liedvogel, Chairman RIN ANG, for collating and circulating the citations and abstracts and to Air Cdre Pinky Grocott for his assistance in preparing the draft of this Newsletter
Honorary Secretary: Dr Emily Baird, Lund University, Sweden The Royal Institute of Navigation 1 Kensington Gore, London SW7 2AT Tel: +44 (0)20 7591 3130 Fax: +44 (0)20 7591 3131
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