Emu - Austral Ornithology Volume 116, Issue 1, 2016 Summaries

Nest-building males trade off material collection costs with territory value Ida E. Bailey, Kate V. Morgan, H. Dieter Oschadleus, Stacy L. DeRuiter, Simone L. Meddle and Susan D. Healy Emu – Austral Ornithology 116(1), 1–8 http://www.publish.csiro.au/paper/MU15022.htm Many build a nest to contain their eggs and chicks. To do this they must choose appropriate material but to conserve energy, they will collect materials from locations as near to their nests as possible. We observed nest building by male Cape Weaverbirds to investigate which materials the birds chose and where they went to get them. Male Cape Weavers build multiple nests in a colony and try to persuade females to choose one of their nests over the nest of a rival. As expected, the nest- building males typically collected nest material from plants with long, strong leaves. Unexpectedly, however, males that flew further to collect material both built more nests and attracted more females. It is not yet clear whether the benefits gained from attracting more females outweighs the higher costs of flying further to collect nest material.

Placement of re-nests following predation: are birds managing risk? Christa Beckmann and Paul G. McDonald Emu – Austral Ornithology 116(1), 9–13 http://www.publish.csiro.au/paper/MU15064.htm Nest predation is the largest source of reproductive failure for most species. Thus, placing nests in ‘safe’ locations that minimise nest predation risk is vital. After having lost a nest to a predator, some bird species have been shown to place their next nest in a new location with different characteristics – for example, in an area of increased cover, or at a different height above ground. In this study we examined the re-nesting behaviour of Bell Miners (Manorina melanophrys), a species of endemic to Australia. Female Bell Miners can build up to five nests in a breeding season. We found that female miners did indeed manage predation risk by reducing the height from the ground at which they placed re-nests following predation events, demonstrating that females can access and modify their behaviour based on predator activity in an area.

Population trends over 50 years of a Pied Imperial-Pigeon breeding colony on North Brook Island, a tropical Great Barrier Reef island, Australia John Winter, Dave Green, Margaret Thorsborne and Mark Parsons Emu – Austral Ornithology 116(1), 14–21 http://www.publish.csiro.au/paper/MU15026.htm This paper examines data arising from long-term monitoring of a Pied Imperial-Pigeon breeding colony on a Great Barrier Reef island, begun by Arthur and Margaret Thorsborne in 1965. The authors cite 19th-century observations testifying to the enormous numbers of the birds at this and nearby colonies, as well as expressions of 20th-century concern at the decline wrought by regular, large-scale shoots. When large-scale shooting ceased, this decline was followed by exponential increase over the next 25 years, with numbers then stabilising until Cyclone Yasi destroyed the birds’ nesting and feeding habitat in 2011. While not yet reaching pre-cyclone numbers, the colony’s rapid recovery from this natural disaster indicates that the birds’ displacement was temporary. Limiting factors, such as depletion of the pigeons’ native food resources, other ongoing impacts of Yasi and possible adverse impacts at their wintering grounds in Papua New Guinea, are discussed. The paper recognises the

importance of data gathered by such long-term projects and the benefits that come from the involvement and interaction of the management authorities and volunteers who maintain the counts, using much the same methods as those devised by the Thorsbornes 50 years ago.

Acoustic features within a forest bird community of native and introduced species in New Zealand Joseph F. Azar and Ben D. Bell Emu – Austral Ornithology 116(1), 22–31 http://www.publish.csiro.au/paper/MU14095.htm Species living in the same habitat may tend to use vocalisations that achieve optimal sound transition, leading to increasing similarities between them. Alternatively, species may reduce overlapping of their vocalisations by increasing their variability. In this study, vocalisations of 16 bird species were examined within a forest bird community in New Zealand, and the acoustic range that each species occupied was quantified. We found that species’ vocalisations were highly diverse. Vocalisations of introduced species were more similar, while vocalisations of native species were more diverse. Vocalisation frequency was correlated with perch height and body weight, representing acoustic adaptation to different transmission properties associated with different elevations, or perhaps as a by- product of the physiological parameter of body weight. The results support the acoustic niche hypothesis in that bird vocalisations appear to have evolved towards divergence. This study provides new insights into the importance of acoustic partitioning in the evolution of vocalisations.

Conservation status and reintroduction of the Cocos Buff-banded Rail, Gallirallus philippensis andrewsi J. C. Z. Woinarski, I. MacRae, T. Flores, T. Detto, J. Reid, C. Pink, S. Flakus, M. Misso, N. Hamilton, R. Palmer, K. Morris, L. Znidersic and B. Hill Emu – Austral Ornithology 116(1), 32–40 http://www.publish.csiro.au/paper/MU15052.htm Many plant and species are restricted to single islands, or single island groups. Such species have had a particularly high rate of extinction. The Cocos Buff-banded Rail occurs only on the Australian external territory of the Cocos (Keeling) Islands, a group of about 27 small islands with total area of 15 km2 in the north-eastern Indian Ocean. This bird has suffered a catastrophic decline since human settlement of the islands, and by c. 1990 was restricted to a single isolated island (the 1-km2 Pulu Keeling); hence, it is regarded as endangered. This study describes the reintroduction in April 2013 of 39 rails from this island to another island in the group. The reintroduced population has been monitored by radio-tracking, remote cameras and transect surveys. By June 2015, it had increased to 121 individuals, demonstrating that this species can respond rapidly with effective control of threats.

Using playback and habitat models to estimate the distribution and population size of the critically endangered , aubryana, in New Caledonia Yuji Okahisa, Andrew LegaultC, Baptiste Angin, Vivien Chartendrault, Nicolas Barré, Christophe de Franceschi, Thomas Duval, François Tron, Roman Gula and Jörn Theuerkauf Emu – Austral Ornithology 116(1), 41–47 http://www.publish.csiro.au/paper/MU15036.htm The Crow Honeyeater, endemic to the main island of New Caledonia, is a critically endangered bird, but is poorly known because of its elusive nature. We conducted playback surveys to assess its distribution, habitat preferences and vocal activity. Crow responded well to playback and our surveys revealed two distinct populations, separated by ~250 km: one small population in the north of the island and another, larger, population in the south. Approximately 315–700 km² of suitable habitat remains for the species, corresponding to a maximum estimated population of 315–700 breeding pairs. The size and range of the Crow Honeyeater population is much smaller than previously assumed and comprehensive management will be required to ensure its survival.

Evidence of an unreported negative effect of fisheries discards on seabirds: death by choking on the Atlantic Midshipman, Porichthys porosissimus, in southern Brazil Victória R. F. Benemann, Lucas Krüger, Fernanda C. L. Valls and Maria V. Petry Emu – Austral Ornithology 116(1), 48–51 http://www.publish.csiro.au/paper/MU14106.htm Our main goal was to describe an unreported threat to seabirds caused by fisheries discards in Brazilian waters: choking on discarded fish of the species Atlantic Midshipman (Porichthys porosissimus). Since 2007, we have been monitoring the southern Brazilian coast to collect beachcast seabird carcasses in an attempt to understand the impact of anthropogenic activities such as pollution and interactions with fisheries on the marine environment. Over 6 years (2007–2013), we registered five dead seabird specimens – Atlantic Yellow-nosed Albatross (Thalassarche chlororhynchos), Cory’s Shearwater (Calonectris diomedea), Sooty Shearwater (Ardenna grisea), Great Shearwater (Ardenna gravis) and Manx Shearwater (Puffinus puffinus) – with an Atlantic Midshipman stuck in their throats. Although this species has no commercial value, this phenomenon has not been consistently described, and the consequences of the consumption of fishery discards by seabirds in Brazilian waters remain poorly understood.

Anthropogenic trauma is the most prevalent cause of mortality in Little Penguins (Eudyptula minor) in Perth, Western Australia B. L. Cannell, K. Campbell, L. Fitzgerald, J. A. Lewis, I. J. Baran and N. S. Stephens Emu – Austral Ornithology 116(1), 52–61 http://www.publish.csiro.au/paper/MU15039.htm From 2003–2012, 159 necropsies were performed on Little Penguins found in the Perth region, Western Australia. Given the close proximity of the penguin colonies in this region to increasingly populated urban areas, the aims of this study were to: 1) determine causes of mortality; 2) determine the proportion of deaths caused by humans; 3) use the information from 1) and 2) to help guide management strategies; and 4) identify potential threats to coastal seabirds in general. Trauma, most likely due to watercraft, was the major cause of mortality. The next most common cause of mortality, starvation, was more likely to occur in spring and summer. High temperatures in summer were associated with penguins dying from overheating. We recommend that management strategies for penguin colonies near high levels of watercraft activity should take into account the risk of injury or death from watercraft strikes.

Annual variation in recruitment and age-specific survival of Little Penguins, Eudyptula minor Philippa Agnew, Chris Lalas, Janine Wright and Steve Dawson Emu – Austral Ornithology 116(1), 62–70 http://www.publish.csiro.au/paper/MU15072.htm To improve our understanding of annual changes in wildlife populations, it is important to determine the proportion of individuals in a population that survive from one year to the next. In longer-lived species, it is also important to examine data collected over a long period. For our study, we examined a long-term dataset, spanning 19 years, to calculate the probability of survival for Little Penguins at Oamaru, New Zealand. Our aims were to determine whether the probability of survival related to the age and breeding status of individuals, and how survival varied annually. We found survival to be lower for penguins in their first year of life compared with older penguins. The penguins’ survival did not decrease with old age (>13 years), however. The comprehensive monitoring programme in place at Oamaru has led to a high probability of recapturing breeding penguins each year.

Forensic genetic evidence of beak and feather disease virus infection in a Powerful Owl, Ninox strenua Subir Sarker, Chris Lloyd, Jade Forwood and Shane R. Raidal Emu – Austral Ornithology 116(1), 71–74 http://www.publish.csiro.au/paper/MU15063.htm In this paper, we report forensic evidence of naturally occurring beak and feather disease virus (BFDV) infection in a Powerful Owl fledgling that had feather abnormalities characteristic of psittacine beak and feather disease. The owl was most likely infected as a nestling after it was fed a rainbow lorikeet with the disease because the virus found in the owl matched closely with BFDV circulating among lorikeets. Until recently the virus, which causes devastating feather disease in parrots and cockatoos and is listed as a key threatening process for critically endangered species such as the Orange-bellied Parrot, was thought to be confined to psittacine birds. Rare spill-over infection of the virus into other birds such as rainbow bee-eaters is being increasingly recognised with advances in diagnostic testing and has far-reaching implications that challenge current understanding of viral disease ecology as well as for disease management of captive psittacine bird flocks.

Long incubation bouts and biparental incubation in the nomadic Banded Stilt Reece D. Pedler, Michael A. Weston and Andrew T. D. Bennett Emu – Austral Ornithology 116(1), 75–80 http://www.publish.csiro.au/paper/MU15061.htm One of Australia’s most intriguing birds, the Banded Stilt is renowned for its nomadic movements between temperate coastal wetlands and the arid interior after rain. After flooding rains inundate vast salt lakes in the Australian outback, these wading birds arrive in their thousands from the coast and nest in dense colonies on tiny islands. This strategy is geared towards rapid reproduction in the face of short-lived water and their brine shrimp food. The remote nature and unpredictable timing of breeding means that the details of this behaviour have been little studied. We used day–night surveillance cameras to investigate the incubation behaviour of Banded Stilts in a 9000-pair nesting colony on Lake Torrens in outback South Australia during winter 2013. The footage revealed that both Banded Stilt parents were involved in the incubation of the eggs; unexpectedly, they undertook some of the longest incubation shifts ever recorded in wading birds. Males attended the nest during hatching and are likely to care for the chicks prior to fledging – a strategy that allows the female to lay a second clutch if water levels persist.

Breeding success of a subtropical Little Tern, Sternula albifrons sinensis, colony Jason B. Searle, J. Blair Prince, David Stewart and Penn Lloyd Emu – Austral Ornithology 116(1), 81–85 http://www.publish.csiro.au/paper/MU15062.htm Shorebirds that nest on coastal beaches are vulnerable to reduced breeding success from increasing disturbance from human recreational activities and predation by introduced predators such as foxes. Consequently, the populations of many shorebirds have declined. Successful management of these birds depends critically on understanding constraints on breeding success. We studied the breeding success of a Little Tern (Sternula albifrons sinensis) colony nesting on a coastal sandspit in south-east Queensland that is exposed to increasing human recreational use and where management is limited to information signage. Egg failure was mostly caused by sand burial during strong winds and tidal flooding. The number of flying young (fledglings) produced per pair each year averaged 0.66 fledglings, slightly lower than averages of 0.71 to 0.77 fledglings per pair at more intensively managed nesting colonies in New South Wales, but still sufficient to ensure an increasing Little Tern population.

Corticosterone responses to capture and restraint in Australasian Gannets, Morus serrator, at Cape Kidnappers, New Zealand John F. Cockrem, E. Jane Candy, Murray A. Potter and Gabriel E. Machovsky-Capuska Emu – Austral Ornithology 116(1), 86–90 http://www.publish.csiro.au/paper/MU15012.htm Birds can respond to threats or potential threats in their immediate environment with increased secretion of a hormone called corticosterone. This hormone is similar to cortisol, which is secreted during stressful situations in mammals, including humans. The hormones increase blood glucose levels and help cope with threatening situations. Corticosterone responses to capture can be measured in birds, with the size of the responses indicating how sensitive individual birds are to their environment. The aim of the present study was to describe corticosterone responses to capture in Australasian Gannets at Cape Kidnappers, New Zealand. Corticosterone concentrations were low initially, then increased after capture in all gannets to reach concentrations similar to those reported for the blue-footed booby, which is closely related to the Australasian Gannet. Further studies of corticosterone in gannets and other Australasian seabirds will be worthwhile to provide information about how these seabirds can respond to changes in their environment.

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