Ecological Segregation Among Thick-Billed Murres (Uria Lomvia) and Common Murres (Uria Aalge) in the Northwest Atlantic Persists Through the Nonbreeding Season L

Total Page:16

File Type:pdf, Size:1020Kb

Ecological Segregation Among Thick-Billed Murres (Uria Lomvia) and Common Murres (Uria Aalge) in the Northwest Atlantic Persists Through the Nonbreeding Season L 447 ARTICLE Ecological segregation among Thick-billed Murres (Uria lomvia) and Common Murres (Uria aalge) in the Northwest Atlantic persists through the nonbreeding season L. McFarlane Tranquilla, W.A. Montevecchi, A. Hedd, P.M. Regular, G.J. Robertson, D.A. Fifield, and R. Devillers Abstract: To study the influence of inter- and intra-specific interactions on patterns of ecological segregation in nonbreeding habitat, we used geolocators to track year-round movements of congeneric and partially sympatric Thick-billed Murres (Uria lomvia (L., 1758)) and Common Murres (Uria aalge (Pontoppidan, 1763)) from seven Canadian colonies during 2007–2011. Locations from 142 individuals were (i) examined for species- and colony-specific spatiotemporal patterns, (ii) mapped with environmental data, and (iii) used to delineate core wintering areas. Compared with Common Murres, Thick-billed Murres dispersed across a wider range of latitudes and environments, had larger winter ranges, and showed greater variation in seasonal timing of movements. These interspecific differences were consistent at two scales: among colonies spanning a wide latitudinal range and at a sympatric colony. Intraspecifically, nonbreeding ecological segregation was more pronounced among colonies of Thick- billed Murres than of Common Murres: colonies of Thick-billed Murres tended to follow distinct movement patterns and segregate by latitude, whereas colonies of Common Murres segregated very little; moreover, the extent of segregation was more variable among Thick-billed Murres than Common Murres. For Thick-billed Murres, rather than complete divergence of winter ecological niche from Common Murres, we found a “widening” of an overlapping niche. This strategy of increased movement flexibility may enable Thick-billed Murres to mitigate competition both intra- and inter-specifically; we propose this movement strategy may have played a role in species divergence. Key words: Uria aalge, Uria lomvia, movement ecology, niche segregation, seabird tracking, wintering areas, seasonal variation. Résumé : Afin d’étudier l’influence des interactions interspécifiques et intraspécifiques sur les motifs de ségrégation écologique dans les habitats autres que de reproduction, nous avons utilisé des géolocalisateurs pour suivre les déplacements durant toute l’année de guillemots de Brünnich (Uria lomvia (L., 1758)) et de guillemots marmettes (Uria aalge (Pontoppidan, 1763)) congénères et partiellement sympatriques de sept colonies canadiennes, de 2007 a` 2011. Les emplacements de 142 individus ont été For personal use only. (i) examinés pour en déterminer les motifs spatiotemporels propres a` chaque espèce et a` chaque colonie, (ii) cartographiés avec des données expérimentales et (iii) utilisés pour délimiter les aires d’hivernage principales. Par rapport aux guillemots marmettes, les guillemots de Brünnich se dispersaient sur une plus grande fourchette de latitudes et de milieux et présentaient des aires d’hivernage plus grandes et une plus grande variation du moment des déplacements durant les saisons. Ces différences interspécifiques étaient cohérentes a` deux échelles, soit entre différentes colonies couvrant une large fourchette de latitudes et a` l’intérieur d’une colonie sympatrique. Au sein de l’espèce, la ségrégation écologique en dehors de la période de reproduction était plus prononcée entre les colonies de guillemots de Brünnich qu’entre celles de guillemots marmettes; les colonies de guillemots de Brünnich tendaient a` suivre des motifs de déplacements distincts et a` se ségréger selon la latitude, alors que les colonies de guillemots marmettes ne présentaient qu’une très faible ségrégation; en outre, l’ampleur de la ségrégation était plus variable chez les guillemots de Brünnich que chez les guillemots marmettes. Plutôt qu’une divergence complète de la niche écologique hivernale des guillemots de Brünnich par rapport a` celle des guillemots marmettes, nous avons observé « l’élargissement » d’une niche chevauchante commune. Cette stratégie de souplesse accrue des déplacements pourrait per- mettre aux guillemots de Brünnich d’atténuer la concurrence tant intraspécifique qu’interspécifique; nous proposons que cette stratégie de déplacement pourrait avoir joué un rôle dans la divergence des espèces. [Traduit par la Rédaction] Mots-clés : Uria aalge, Uria lomvia, écologie des déplacements, ségrégation de niche, localisation d’oiseaux marins, aires d’hivernage, variations saisonnières. Introduction dietary partitioning, exhibiting varied patterns of space use, for- When resources are limited, sympatric and competing species aging activity, and diet (MacArthur and Levins 1964; Phillips et al. Can. J. Zool. Downloaded from www.nrcresearchpress.com by MEMORIAL UNIV OF NEWFOUNDLAND on 05/31/18 are able to coexist through ecological segregation (Lack 1945; Holt 2009; Masello et al. 2010), all of which are well-documented strat- 2009). Sympatric species reduce competition through habitat and egies of niche partitioning at colony sites during the breeding Received 30 November 2014. Accepted 25 March 2015. L. McFarlane Tranquilla,* W.A. Montevecchi, A. Hedd, and P.M. Regular. Cognitive and Behavioural Ecology, Department of Psychology, Memorial University of Newfoundland, St. John’s, NL A1B 3X9, Canada. G.J. Robertson and D.A. Fifield. Wildlife Research Division, Environment Canada, 6 Bruce Street, Mount Pearl, NL A1N 4T3, Canada. R. Devillers. Department of Geography, Memorial University of Newfoundland, St. John’s, NL A1B 3X9, Canada. Corresponding author: L. McFarlane Tranquilla (e-mail: [email protected]). *Present address: Bird Studies Canada, 17 Waterfowl Lane, Sackville, NB E4L 1G6, Canada. Can. J. Zool. 93: 447–460 (2015) dx.doi.org/10.1139/cjz-2014-0315 Published at www.nrcresearchpress.com/cjz on 13 April 2015. 448 Can. J. Zool. Vol. 93, 2015 season (Wood et al. 2000; Grémillet et al. 2004; Gonzáles-Solís and Hipfner 2000; Ainley et al. 2002). Because the two species are et al. 2007; Wakefield et al. 2013). Following breeding, seabirds are morphologically and ecologically very similar (Gaston and Jones released from central-place foraging constraints and, given the 1998), competition and pressures for divergence between them is potential for dispersal throughout the marine environment, one likely intense. Dietary niche partitioning is supported by slight might expect a reduction in resource competition that diffuses differences in bill morphology (Bédard 1969) reflecting preferences: the pressure for ecological segregation. However, marine re- Thick-billed Murres consume a wide variety of fishes (e.g., sources are patchily distributed, and important wintering areas Arctic cod (Boreogadus saida (Lepechin, 1774)), blennies (suborder can concentrate large numbers of nonbreeding seabirds and other Blennioidei)) and zooplankton (for which their tongue and palate top predators (e.g., Grand Banks of Newfoundland: Frederiksen are better adapted; Bédard 1969), whereas Common Murres con- et al. 2011; Hedd et al. 2012; Mosbech et al. 2012; Magnusdottir et al. sume predominantly shoaling fishes (e.g., capelin (Mallotus villosus 2012; Mid-Atlantic Ridge: Walli et al. 2009; Egevang et al. 2010; (Müller, 1776)), sand lance (genus Ammodytes L., 1758)) with a small North Pacific Transition Zone: Block et al. 2011; Benguela Upwell- proportion of invertebrates (Gaston and Jones 1998). In the North- ing: Stenhouse et al. 2011), where competition for resources is west Atlantic, they have a relatively segregated breeding distribu- likely to persist. Here, how inter- and intra-specific interactions tion (Thick-billed Murres concentrating at higher latitudes; see may influence ecological segregation in wintering areas (Ratcliffe also study colony sizes in Table 1), but sympatry occurs where et al. 2014) is another important piece of the puzzle. their ranges overlap. At sympatric colonies, subtle differences Research on ecological segregation among nonbreeding sea- in phenology, breeding-site locations, and prey exploitation birds has unfolded using two approaches. First, studies dedicated might decrease interspecific competition (Birkhead and Nettleship to investigating nonbreeding segregation usually compare winter 1987a, 1987b; Barrett et al. 1997). Following breeding, both species distributions of sympatric species or neighboring populations. winter at Low Arctic latitudes of the North Atlantic Ocean (Tuck Among the most well-studied have been seabirds of the Southern 1961; Gaston and Hipfner 2000; Ainley et al. 2002). Although Tuck Atlantic and Indian oceans, where sympatric groups (e.g., petrels, (1961) considered them to segregate partially by thermal prefer- albatrosses, penguins) from Antarctic colonies exhibit species- ence (with Thick-billed Murres occurring in colder waters and specific segregation into different water masses of the Antarctic Common Murres occurring in warmer waters), other studies have Circumpolar Current, usually targeting different diets (Cherel blurred this categorization, rendering it unclear how winter strat- et al. 2006, 2007; Phillips et al. 2009; Thiebot et al. 2012; Ratcliffe egies or preferences of murres are influenced by geography and et al. 2014). Winter spatial and diet segregations by sex also occurs habitat preference, colony of origin, or the presence of competi- in some species (Phillips et al. 2005). Very few studies have com- tors (Gaston et al. 2011, Fort et al. 2012, Linnebjerg et al. 2013). In pared nonbreeding segregation outside the Antarctic system. the
Recommended publications
  • Breeding Ecology and Extinction of the Great Auk (Pinguinus Impennis): Anecdotal Evidence and Conjectures
    THE AUK A QUARTERLY JOURNAL OF ORNITHOLOGY VOL. 101 JANUARY1984 No. 1 BREEDING ECOLOGY AND EXTINCTION OF THE GREAT AUK (PINGUINUS IMPENNIS): ANECDOTAL EVIDENCE AND CONJECTURES SVEN-AXEL BENGTSON Museumof Zoology,University of Lund,Helgonavi•en 3, S-223 62 Lund,Sweden The Garefowl, or Great Auk (Pinguinusimpen- Thus, the sad history of this grand, flightless nis)(Frontispiece), met its final fate in 1844 (or auk has received considerable attention and has shortly thereafter), before anyone versed in often been told. Still, the final episodeof the natural history had endeavoured to study the epilogue deservesto be repeated.Probably al- living bird in the field. In fact, no naturalist ready before the beginning of the 19th centu- ever reported having met with a Great Auk in ry, the GreatAuk wasgone on the westernside its natural environment, although specimens of the Atlantic, and in Europe it was on the were occasionallykept in captivity for short verge of extinction. The last few pairs were periods of time. For instance, the Danish nat- known to breed on some isolated skerries and uralist Ole Worm (Worm 1655) obtained a live rocks off the southwesternpeninsula of Ice- bird from the Faroe Islands and observed it for land. One day between 2 and 5 June 1844, a several months, and Fleming (1824) had the party of Icelanderslanded on Eldey, a stackof opportunity to study a Great Auk that had been volcanic tuff with precipitouscliffs and a flat caught on the island of St. Kilda, Outer Heb- top, now harbouring one of the largestsgan- rides, in 1821. nettles in the world.
    [Show full text]
  • Population Status, Reproductive Ecology, and Trophic Relationships of Seabirds in Northwestern Alaska
    POPULATION STATUS, REPRODUCTIVE ECOLOGY, AND TROPHIC RELATIONSHIPS OF SEABIRDS IN NORTHWESTERN ALASKA by Alan M. Springer, Edward C. Murphy, David G. Roseneau, and Martha 1. Springer LGL Alaska Research Associates, Inc. P. O. BOX 80607 Fairbanks, Alaska 99708 Final Report Outer Continental Shelf Environmental Assessment Program Research Unit 460 April 1982 127 TABLE OF CONTENTS ~ I. SUMMARY OF OBJECTIVES, CONCLUSIONS, AND IMPLICATIONS WITH RESPECT TO OCS OIL AND GAS DEVELOPMENT. 131 II. INTRODUCTION. 131 III. CURRENT STATEOFKNOWLEDGE . 133 IV. STUDY AREAS. 133 Va. MURRE NUMBERS - METHODS. 135 VIa. MURRE NUMBERS-RESULTS.. 140 VIIa. MURRE NUMBERS-DISCUSSION . 145 VIIb. FOOD HABITS-METHODS. 162 VIIb . FOOD HABITS-RESULTS. 163 VIIb . FOOD HABITS -DISCUSSION. , . 168 VIIc . KITTIWAKES -METHODS. 203 VIIc . KITTIWAKES -RESULTS. 204 VIIC . KITTIWAKES -DISCUSSION. 206 VIId . OTHER SPECIES-METHODS.. 209 VId & VIId. OTHER SPECIES - RESULTS AND DISCUSSION . 209 VIII. CONCLUSIONS. 231 IX. NEEDS FORFUTURESTUDY . 232 x. LITEMITURECITED. 233 129 I. SUMMARY OF OBJECTIVES, CONCLUSIONS AND IMPLICATIONS WITH REGARD TO OCS OIL AND GAS DEVELOPMENT A. Objectives The objective of RU 460 is to describe important components of the biology of seabirds in northern Alaska, including relationships among seabirds, their supporting food webs and the physical environment. To accomplish this objective we have concentrated on studies of thick-billed murres (Uris lomvia), common murres (U. aazge) and black-legged kittiwakes (Rissa tridactyZa), the most wide-spread, and among the most numerous, of all seabird species in the region. Moreover, murres and kittiwakes are easily studied compared to other species, and are sensitive indicators of environmental change. B: Conclusions Our principal conclusions are that numbers of murres at two major breeding colonies in northern Alaska are declining and that annual vari- ability is high in a variety of elements of murre and kittiwake breeding biology.
    [Show full text]
  • Population Estimates and Temporal Trends of Pribilof Island Seabirds
    POPULATION ESTIMATES AND TEMPORAL TRENDS OF PRIBILOF ISLAND SEABIRDS by F. Lance Craighead and Jill Oppenheim Alaska Biological Research P.O. BOX 81934 Fairbanks, Alaska 99708 Final Report Outer Continental Shelf Environmental Assessment Program Research Unit 628 November 1982 307 ACKNOWLEDGEMENTS Dan Roby and Karen Brink, University of Pennsylvania, Philadelphia, were especially helpful to us during our stay on St. George and shared their observations with us. Bob Day, University of Alaska, Fairbanks, also provided comparative data from his findings on St. George in 1981. We would like to thank the Aleut communities of St. George and St. Paul and Roger Gentry and other NMFS biologists on St. George for their hospitality and friendship. Bob Ritchie and Jim Curatolo edited an earlier version of this report. Mary Moran drafted the figures. Nancy Murphy and Patty Dwyer-Smith typed drafts of this report. Amy Reges assisted with final report preparation. Finally, we’d like to thank Dr. J.J. Hickey for initiating seabird surveys on the Pribi of Islands, which were the basis for this study. This study was funded by the Bureau of Land Management through interagency agreement with the National Oceanic and Atmospheric Administra- tion, as part of the Outer Continental Shelf Environmental Assessment Program. 308 TABLE OF CONTENTS ~ ACKNOWLEDGEMENTS. ● . ● . ● . ● . 308 EXECUTIVE SUMMARY . ✎ . ● ✎ . ● . ● ● . ✎ . ● ● . 311 INTRODUCTION. ✎ . ● ✎ . ✎ . ✎ ✎ . ● ✎ ● . ● ✎ . 313 STUDY AREA. ● . ✎ ✎ . ✎ . ✎ ✎ . ✎ ✎ ✎ . , . ● ✎ . ● . 315 METHODS . ● . ✎
    [Show full text]
  • Uria Aalge ) Eggshells in Atlantic Canada
    08_13025_Bond_NOTE_FINAL_CFN 128(1) 2017-09-01 4:01 AM Page 72 Notes Thickness of Common Murre ( Uria aalge ) Eggshells in Atlantic Canada DonAlD W. P iriE -H Ay and AlExAnDEr l. B onD 1 Department of Biology, University of Saskatchewan, and Environment Canada, 11 innovation Boulevard, Saskatoon, Saskatchewan S7n 3H5 Canada 1Corresponding author: [email protected] Pirie-Hay, Donald W., and Alexander l. Bond. 2014. T hickness of Common Murre ( Uria aalge ) eggshells in Atlantic Cana - da. Canadian Field-naturalist 128(1): 7 2–76. reported values for eggshell thickness in Common Murre ( Uria aalge ) are few, and even fewer since the decline in use of organochlorine pesticides and other environmental pollutants that caused significant thinning of shells. The eggshells of Common Murres and Thick-billed Murres ( Uria lomvia ) are among the thickest and heaviest, proportionately, of any bird and this represents a non-trivial maternal investment. We measured the length and breadth of Common Murre eggs collected from Machias Seal island, new Brunswick, in 2006, and Gull island, newfoundland and labrador, in 2012, and we measured the thickness of the eggshells. Shell thickness was not related to egg size or volume, and it varied in individual eggs. The shells of Common Murre eggs from Machias Seal island (mean and standard deviation [SD] (0.767, SD 0.078 mm) and Gull island (0.753, SD 0.057 mm ) were significantly thicker than any previously reported value and among the thickest of all birds . Such thickness is likely a result of nesting on rock substrate with no nesting material and, perhaps, high breeding densities.
    [Show full text]
  • A Review of the Fossil Seabirds from the Tertiary of the North Pacific
    Paleobiology,18(4), 1992, pp. 401-424 A review of the fossil seabirds fromthe Tertiaryof the North Pacific: plate tectonics,paleoceanography, and faunal change Kenneth I. Warheit Abstract.-Ecologists attempt to explain species diversitywithin Recent seabird communities in termsof Recent oceanographic and ecological phenomena. However, many of the principal ocean- ographic processes that are thoughtto structureRecent seabird systemsare functionsof geological processes operating at many temporal and spatial scales. For example, major oceanic currents,such as the North Pacific Gyre, are functionsof the relative positions of continentsand Antarcticgla- ciation,whereas regional air masses,submarine topography, and coastline shape affectlocal processes such as upwelling. I hypothesize that the long-termdevelopment of these abiotic processes has influencedthe relative diversityand communitycomposition of North Pacific seabirds. To explore this hypothesis,I divided the historyof North Pacific seabirds into seven intervalsof time. Using published descriptions,I summarized the tectonicand oceanographic events that occurred during each of these time intervals,and related changes in species diversityto changes in the physical environment.Over the past 95 years,at least 94 species of fossil seabirds have been described from marine deposits of the North Pacific. Most of these species are from Middle Miocene through Pliocene (16.0-1.6 Ma) sediments of southern California, although species from Eocene to Early Miocene (52.0-22.0 Ma) deposits are fromJapan,
    [Show full text]
  • The Amazon River Dolphin
    lMATA Dedicated to those who serve marine mammal science through training, public display, research, husbandry, conservation, and education. Back. Cover: Graphics play like a sentinel over Tacoma. an important role in the Washington, site of the 22nd public display of animals; Annual IMATA Conference. they are essential education From COver: Chuckles, the Photograph by Mark Holden. tools that provide the public only Amazon River dolphin with a wide range of in North America, resides at important information about the Pittsburgh Zoo in animals and the environment. Pittsburgh, Pennsylvania. Photograph by Marcye Photograph by n'm Smith. Miller-Lebert Copyright 1994. AIl of the articles contained within Soundings are the personal views of the respective authors and not necessarily the views of IMATA . DESIGN & PRODUCTION: I-deal Services, San Diego, California (619) 275-1800 Page 2 Spring 1994 ~- ---­ ---- --- lMATA PUBLlCAnONS COMMlTIEE Editor John Kirtland Regional The Dolphin Expedence Editorial Director Reports Dave Force Designed to help members Sea World Q/Texas keep track of what is going Assodate Editor on in other facilities around :.Jedra Hecker the world. i\arional Aquadum in Baltimore IMATA'S Growth Contributing Editors Jim Clarke and Development Pete Davey Greg Dye IMATA is dedicated to Steve Shippee providing and advancing the Kari Snelgrove The Amazon most professional. effective, Contributing Writers and humane care and Kathy Sdao River Dolphin handling of all marine Jeff Fasick Learning about this species is a animals in all habitats. Editoria) Advisory Board challenge. Few Inia have been Randy Brill, Ph.D. housed in captivity for long NCCOSCINRaD periods making research of the Brian E.
    [Show full text]
  • Razorbill Alca Torda in North Norway
    THE EFFECT OF PHYSICAL AND BIOLOGICAL PARAMETERS ON THE BREEDING SUCCESS OF RAZORBILLS (ALCA TORDA L. 1758) ON MACHIAS SEAL ISLAND, NB IN 2000 AND 2001 by Virgil D. Grecian Bachelor of Science (Hon), Memorial University of Newfoundland, 1996 A Thesis Submitted in Partial Fulfilment of the Requirements for the Degree of Master of Science in the Graduate Academic Unit of Biology Supervisors: A.W. Diamond, Ph.D., Biology and Forestry & Environmental Management, J.W. Chardine, Ph.D., Canadian Wildlife Service Supervisory Committee: D.J. Hamilton, Ph.D., Mt Allison University Examining Board: This thesis is accepted. ………………………………………… Dean of Graduate Studies THE UNIVERSITY OF NEW BRUNSWICK Fredericton, New Brunswick, Canada December, 2004 ABSTRACT The influence of various physical and biological parameters on the breeding biology of Razorbills (Alca torda) on Machias Seal Island (MSI) was studied in 2000 and 2001. The major predators (gulls) on seabird eggs and chicks on MSI are controlled, providing an unusual opportunity to study breeding biology in the virtual absence of predation. The timing of egg-laying was right skewed in both years. A complete survey 10-14 June 2000 of all Razorbill breeding habitat on MSI was combined with radio telemetry to estimate the total number of inaccessible breeding sites that may not have been counted. A corrected breeding pair estimate for MSI is 592 ± 17 pairs. Overall breeding success was 55% in 2000 and 59% in 2001. Most chicks that hatched also departed the island, so differences in breeding success were due chiefly to differences in hatching success. Adults breeding in burrows were more successful than adults in crevice and open nest sites.
    [Show full text]
  • Comparative Breeding Biology of Guillemots Uria Spp. and Razorbills Alca Torda at a Colony in the Northwest Atlantic
    Breeding biology ofGuillemots and Razorbills 121 121 Comparative breeding biology of Guillemots Uria spp. and Razorbills Alca torda at a colony in the Northwest Atlantic Vergelijkende broedbiologie van Zeekoeten en Alken op een kolonie in het Noorwestelijke Atlantische gebied J. Mark+Hipfner&Rachel Bryant Biopsychology Programme. Memorial University ofNewfoundland St. John's. NF. Canada AIB 3X9e-mail:[email protected] the Common Guillemots, We compared various aspectsof breedingbiology ofRazorbills, ” and Brünnich’s Guillemots (the “intermediate auks) at the Gannet Islands, Labrador. Canada, in 1997. In all three species, layingfollowed a strongly right-skewedpattern, In with median laying dates falling within a narrow window between 27-29 June. and comparison topreviousyears, laying was late, relatively synchronous among species. 2 in Razorbills 35 than in either Incubation periods were days longer (median days) guillemot species (33 days), whereas Common Guillemots had longer nestling periods (mean 24 days) than Razorbills (19 days) or Brünnich’s Guillemots (20 days). In all species, there was a tendency for late-laying pairs to contract their breeding periods, in mainly by reducing the duration of the nestling period. Breeding success was high Razorbills (73%) and Common Guillemots (85%), but low in Brünnich’s Guillemots Brünnich Guillemots (51%), largely due to low hatching success. Late-breeding ’s were little this in the other more likely tofail than were earlypairs, but there was indication of two species. Seasonal patterns of colony attendance suggested that there were many young, pre-breeding Brünnich’s Guillemots and Razorbills present; populations of these in since species appear to be faring well at this colony.
    [Show full text]
  • International Black-Legged Kittiwake Conservation Strategy and Action Plan Acknowledgements Table of Contents
    ARCTIC COUNCIL Circumpolar Seabird Expert Group July 2020 International Black-legged Kittiwake Conservation Strategy and Action Plan Acknowledgements Table of Contents Executive Summary ..............................................................................................................................................4 CAFF Designated Agencies: Chapter 1: Introduction .......................................................................................................................................5 • Norwegian Environment Agency, Trondheim, Norway Chapter 2: Ecology of the kittiwake ....................................................................................................................6 • Environment Canada, Ottawa, Canada Species information ...............................................................................................................................................................................................6 • Faroese Museum of Natural History, Tórshavn, Faroe Islands (Kingdom of Denmark) Habitat requirements ............................................................................................................................................................................................6 • Finnish Ministry of the Environment, Helsinki, Finland Life cycle and reproduction ................................................................................................................................................................................7 • Icelandic Institute of Natural
    [Show full text]
  • Common Murre •.• Thick-Billed Murre
    j. Field Ornithol., 54(3):266-274 THE FLEDGING OF COMMON AND THICK-BILLED MURRES ON MIDDLETON ISLAND, ALASKA BY SCOTT A. HATCH Three speciesof alcids,Common and Thick-billed murres (Uria aalge and U. lornvia)and the Razorbill (Alca torda),have post-hatchingdevel- opmental patterns intermediate to precocialand semi-precocialmodes (Sealy1973). The youngleave their cliff nestsites at aboutone quarter of adult weight and completetheir growth at sea.At departure, an event here looselyreferred to as "fledging," neither primary nor secondary flight feathersare grown, but well-developedwing covertsenable lim- ited, descendingflight. The adaptivesignificance of thispattern maybe that leadingthe young to distantfeeding areasis more efficientthan lengthy foraging flights by adultsonce the chicks'energetic requirements exceed some critical level (Sealy 1973, Birkhead 1977). The risk to predation is probably greater in exposednest sitesthan at sea, contributing further to the selectiveadvantage of earlyfledging (Cody 1971, Birkhead1977). Given these constraints,however, larger chickswould be expected to better survivethe rigorsof fledging,increased activity at sea,and the vagaries of weather. Hedgren (1981) analyzed278 recoveriesof CommonMurres banded as fledglingsand found no significantrelationship between fledging weight and subsequentsurvival. This result is paradoxicalin view of a strong expectationto the contrary and evidencethat such an effect occursin other speciesof birds (Perrins 1965, Perrinset al. 1973, O'Con- ner 1976). Hedgren suggestedthe nestlingperiod of murres,averaging about3 weeks,is determinednot by a thresholdin bodysize, but by the relativelyconstant time requiredto completefeather growth.Birkhead (1977) alsoemphasized the need for chicksto attain a critical weight: wing-arearatio prior to fledging. Clearly, however,body weight and feather developmentare not mutuallyexclusive factors affecting fledg- ling survival.
    [Show full text]
  • Alcid Identification in Massachusetts
    ALCID IDENTIFICATION IN MASSACHUSETTS by Richard R. Veit, Tuckernuck The alcldae, a northern circvimpolar family of sesbirds, are memhers of the order Charadrilformes and thus most closely related to the gulls, skuas, and shorehirds. All alcids have approximately elliptical bodies and much reduced appendages, adaptations for insulation as well as a streamlined trajectory under water. Their narrow flipperlike wings are modified to reduce drag durlng underwater propulsión, and are, therefore, comparatively inefficient for flight. Razorbills, murres, and puffins feed predominately on fish, such as the sand launce, capelin, Arctic cod, herring, and mackerel. The Dovekie, by far the smallest Atlantic alcid, eats zooplankton exclusively, such as the superabundant "krill." The Black Guillemot, unique.in its con- finement to the shallow littoral zone, feeds largely on rock eels or gunnel. As with many pelagic birds, the alcids' dependence on abundant marine food restricts them to the productive vaters of the high latitudes. Bio- logical productivity of the oceans increases markedly towards the poles, largely because the low surface temperaturas there maintain convection currents which serve to raise large quantities of dissolved mineral nu­ triente to the siirface. The resultant high concentration of nutriente near the surface of polar seas supports enormous populations of plankton and, ultimately, the fish upon which the largar alcids feed. Alcids are comparatively weak flyers and are not regularly migratory, but rather disperse from their breeding ranga only when forced to do so by freezing waters or food scarcity. Massachusetts lies at the periphery of the ranges of these birds, with the exception of the Razorbill. It i& only under exceptional circumstances, such as southward irruptions coupled with strong northeasterly storms that substantial numbers of alcids are observad along the Massachusetts coastline.
    [Show full text]
  • Age and Sex of Common Murres Uria Aalge Recovered During the 1997-98 Point Reyes Tarball Incidents in Central California
    51 AGE AND SEX OF COMMON MURRES URIA AALGE RECOVERED DURING THE 1997-98 POINT REYES TARBALL INCIDENTS IN CENTRAL CALIFORNIA HANNAHROSE M. NEVINS1 & HARRY R. CARTER 2, 3 1Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039 USA, e-mail: [email protected] 2Department of Wildlife, Humboldt State University, Arcata, CA 95521 USA 3Present address: 5700 Arcadia Road, Apt #219, Richmond, B.C. V6X2G9 Canada Received 9 April 2003, accepted 11 October 2003 SUMMARY NEVINS, H. M. & CARTER, H. R. Age and sex of Common Murres Uria aalge recovered during the 1997-98 Point Reyes Tarball Incidents in central California. Marine Ornithology 31: 51-58. We examined 1,138 Common Murre Uria aalge carcasses recovered along the central California coast from November 1997 through March 1998 during the Point Reyes Tarball Incidents, a prolonged oiling event traced to the sunken vessel S. S. Jacob Luckenbach. We used head plumage, supraorbital ridge, and bursa of Fabricius, to classify age among carcasses as hatch-year (HY), or after-hatch year (AHY). We then separated AHY birds into two maturity categories based on gonad development: subadult and adult. The observed age class composition (14.6% HY, 37.6% subadult, and 47.8% adult) was not different from expected values generated with a stage-based matrix model that assumed a year-round resident population. The sex ratio for HY birds was equal (1.2:1), indicating little difference in at-sea distribution among male and female HY birds during winter. We found male-biased sex ratios in subadult (1.6:1) and adult (1.5:1) age classes.
    [Show full text]