Showing papers in "Emu in 2009"
TL;DR: A full research agenda for avian phylogeography in the Australo-Papuan region is suggested that spans diverse topics: the need for more studies of pelagic birds, spatio-temporal links between New Guinea and Australia, island populations, testing of long-established biogeographical hypotheses, and integration of molecular and non-molecular datasets into integrated evolutionary understanding of species and populations.
Abstract: With examples from Australo-Papuan ornithology, we examine the technical and theoretical roots of molecular phylogeography and review its development. We describe the progression from ad hoc interpretation of gene trees in single species phylogeographic studies through to comparative phylogeography and currently advocated model-testing approaches. Mitochondrial DNA (mtDNA) sequences have provided most advances to date, although we demonstrate and advocate the future use of multilocus datasets analysed with coalescent methods. We examine interrelationships among speciation research, historical biogeography, phylogeography and landscape genetics. Mitochondrial paraphyly, in which individuals of one species or population have mtDNA that is more closely related to that of another than to their own, emerges in 44% of Australian studies to date as a common, important result in Australian avian phylogeography. Accordingly, we explore at length its most common causes and its impact on case studies in Australo-Papuan avian phylogeography. The impact of so much paraphyly on avian phylogeography and taxonomy is a major theme of the review. We suggest a full research agenda for avian phylogeography in the Australo-Papuan region that spans diverse topics: the need for more studies of pelagic birds, spatio-temporal links between New Guinea and Australia, island populations, testing of long-established biogeographical hypotheses, and integration of molecular and non-molecular datasets into integrated evolutionary understanding of species and populations. Studying the full continuum of divergences from landscape genetics, to phylogeography, to recently diverged species with evidence of paraphyly, to highly divergent species with many fixed differences will lead to a more complete understanding of the processes and patterns of avian evolution.
103 citations
TL;DR: A field experiment to quantify differences between observers in the detection of birds at Booderee National Park, south-eastern Australia identified highly significant observer differences for estimates of bird species richness and the probability of detection of three exemplar taxa.
Abstract: Use of multiple observers in large-scale bird surveys is often unavoidable. But how significant are observer differences in bird detection? Do observer effects significantly influence inferences ab...
52 citations
TL;DR: This survey represents the first positive identification of BFDV in wild New Zealand endemic psittacines and confirms the risk of spread of the virus between wild populations within this global hotspot of endemic Psittacine diversity.
Abstract: Psittacine beak and feather disease (PBFD) is a highly infectious and potentially fatal viral disease of parrots and their allies caused by the beak and feather disease virus (BFDV). Abnormal feather morphology and loss of feathers are common clinical symptoms of the disease. PBFD also damages the lymphoid tissue and affected birds may die as a result of secondary bacterial or fungal infections. The disease is therefore of concern for conservation biologists and wildlife managers, as it is immunosuppressive and can become an additional threatening factor among critically endangered psittacines. We conducted a PCR-based screening for BFDV in a wild population of the Red-fronted Parakeet (Cyanoramphus novaezelandiae) on Little Barrier Island, New Zealand, during a translocation of this species. Fifty-four parakeets were captured and feather samples collected for molecular screening. We detected BFDV DNA from 15 individuals, but only two showed external signs attributable to PBFD, namely abnormal feather morphology or colouration, loss of feathers and haemorrhagic feathers. Our survey represents the first positive identification of BFDV in wild New Zealand endemic psittacines and confirms the risk of spread of the virus between wild populations within this global hotspot of endemic psittacine diversity.
42 citations
TL;DR: It is predicted that the availability of drainage zones within a group's range will influence offspring dispersal decisions in Chestnut-crowned Babblers at the site studied.
Abstract: An individual’s fitness is assumed to be maximised through early dispersal and independent breeding. However, offspring across a diversity of taxonomic groups delay dispersal and remain with at least one of their parents after reaching sexual maturity. Delayed dispersal and resulting family living are expected to arise when constraints exist on independent reproduction and where offspring benefit by remaining philopatric. A first step to elucidating the nature of such constraints and benefits for a given species is to have an understanding of the social organisation and habitat preferences of a species. The present study examined the social organisation, foraging preferences and characteristics of preferred foraging areas during a breeding season in the cooperatively breeding Chestnut-crowned Babbler (Pomatostomus ruficeps). During the study, groups of Babblers bred plurally in breeding units of two to 13 adults that occupied non-exclusive home-ranges averaging 38 ha, with larger groups occupying larger ranges. Babblers spent most of the day foraging, mostly on the ground, and preferred to forage within drainage zones. The preference for such zones probably arose because they offered both greater vegetative cover from aerial predators and biomasses of potential prey. These findings lead to the prediction that the availability of drainage zones within a group’s range will influence offspring dispersal decisions in Chestnut-crowned Babblers at the site studied.
34 citations
TL;DR: These data suggest that despite the high demand on coastal land for urban development in Moreton Bay, suitable roosting habitat is still available near their foraging areas and that the shorebirds occurring in a subtropical Australian estuary use two generalised types of roosts.
Abstract: Conservation of critical habitats for shorebirds (Charadriiformes : Charadrii), usually requires spatially explicit identification of each habitat. Most non-breeding shorebirds depend on two critical habitats: foraging (intertidal flats) and roosting (safe and open supratidal sites). We used published information on use of high-tide roosts by shorebirds to develop models of roost selection (probability of occurrence) and usage (mean abundance) for 12 species of shorebirds spending the non-breeding season in Moreton Bay, in subtropical eastern Australia. Selection of roosts was most strongly affected by the proximity to a large foraging area, field of view and to a lesser extent by composition of the surrounding landscape. Abundance of the most common species, such as Bar-tailed Godwit (Limosa lapponica), Eastern Curlew (Numenius madagascariensis) and Whimbrel (N. phaeopus), depended on distance to the nearest large foraging area or the size of the roost per se. Our results suggest that the shorebird species occurring in a subtropical Australian estuary use two generalised types of roosts: exposed ocean-front roosts typified by supratidal spits and sandbars and patches of claypan–saltmarsh in the upper reaches of the tidal range surrounded by mangroves. The amount of these habitats available in Moreton Bay was examined by visiting unmonitored sites with a predicted high probability of occupancy by two key species, Eastern Curlew and Bar-tailed Godwit. Few of the unmonitored sites currently supported many shorebirds. These data suggest that despite the high demand on coastal land for urban development in Moreton Bay, suitable roosting habitat is still available near their foraging areas.
34 citations
TL;DR: Investigating how road edges influenced Noisy Miners by comparing the species’ aggressive and foraging behaviour, and location of nests, between road-edge and interior transects in a southern Queensland forest found that road edges do not appear to influence NoisyMiners as strongly as edges between forest and agricultural land do elsewhere in eastern Australia.
Abstract: Increased abundance of Noisy Miners (Manorina melanocephala), a large, aggressive honeyeater, is one of the most important mechanisms through which habitat fragmentation and degradation threaten populations of eastern Australian woodland birds. In inland Queensland, however, Noisy Miners dominate avian assemblages throughout extensive forest areas as well as fragmented landscapes, and our understanding of the factors influencing their behaviour and habitat selection in such relatively intact landscapes is limited. I investigated how road edges influenced Noisy Miners by comparing the species’ aggressive and foraging behaviour, and location of nests, between road-edge and interior transects in a southern Queensland forest. I also investigated Noisy Miner foraging microhabitat preferences and targets of aggression. Noisy Miner nests were more likely to be located near to road edges, but foraging and aggressive interactions occurred with similar frequency near and far from road edges. Such interactions selectively targeted close competitors and a nest predator. Most foraging activity was in the canopy, and selectively within ironbarks (Eucalyptus spp.), suggesting that higher densities of Noisy Miners in more open areas of the forest are unlikely to be related to facilitation of ground-foraging activity. Despite some evidence of a preference for nesting near road openings, road edges do not appear to influence Noisy Miners as strongly as edges between forest and agricultural land do elsewhere in eastern Australia.
31 citations
TL;DR: This work studied group size and extra-pair paternity in South Australia where, unlike other study sites, auxiliary males were relatively uncommon: 16% of nests had one auxiliary male compared to 37–80% with at least one auxiliary per nest in other studies.
Abstract: The Superb Fairy-wren (Malurus cyaneus) is a model system in which to study cooperative breeding and extra-pair paternity. Previous studies in this species have shown that 61-76% of nestlings were extra-pair young and 92-95% of nests contained at least one extra-pair young. Furthermore, the probability of extra-pair paternity was higher when auxiliary males were present. We studied group size and extra-pair paternity in South Australia where, unlike other study sites, auxiliary males were relatively uncommon: 16% of nests had one auxiliary male compared to 37-80% with at least one auxiliary per nest in other studies. We predicted a lower incidence of extra-pair paternity, given the shortage of auxiliary males. Our results did not support this prediction: we found extra-pair paternity among 67% of nestlings and 83% of nests.
26 citations
TL;DR: Phylogenetic relationships among the three species of Stipiturus, based previously on plumage and allozyme data, are confirmed by mtDNA data, which support recognition of Mallee Emu-wren (S. mallee) as a distinct (evolutionary) species from, and sister lineage to, Rufous-crowned Emu
Abstract: The three species of emu-wrens (Maluridae : Stipiturus) are small passerines found in arid to mesic habitats across southern Australia. The geographical distribution of nucleotide sequence diversity of mitochondrial DNA (mtDNA) in emu-wrens was investigated to assess the systematic status of Stipiturus (Aims 1 and 2), particularly in eastern Australia, and to examine closely the population structure of Southern Emu-wren (S. malachurus) in the Mount Lofty Ranges of South Australia (Aim 3). Aim 1: Phylogenetic relationships among the three species of Stipiturus, based previously on plumage and allozyme data, are confirmed by our mtDNA data, which support recognition of Mallee Emu-wren (S. mallee) as a distinct (evolutionary) species from, and sister lineage to, Rufous-crowned Emu-wren (S. ruficeps) rather than Southern Emu-wren. These relationships indicate that any interaction between Mallee and Southern Emu-wrens in south-eastern South Australia is a secondary contact. Aim 2: Within the Southern Emu-wren, which currently comprises eight subspecies, phylogenetic relationships among haplotypes from eastern Australia are not concordant globally with subspecies boundaries, but correspond in part to the most recent classification. A quantitative statistical evaluation of the taxonomic implications of phenotypic variation in these birds is warranted. Eastern haplotypes of Southern Emu-wren show strong phylogeographic structure indicative of allopatric divergence in refugia, with subsequent expansion without widespread introgression. Aim 3: Within the endangered populations of the Mount Lofty Ranges, historical isolation and demographic independence of central and southern populations is supported, corresponding with distribution data, but confirmation using nuclear markers is required. Despite separate subspecific designation of emu-wrens of the Mount Lofty Ranges (which are endangered) and south-eastern South Australia, they share mtDNA haplotypes without strong differentiation and emu-wrens of south-eastern South Australia should be preferred over Kangaroo Island birds for translocations into the MLR, although translocation among populations of the Mount Lofty Ranges is probably a wiser initial strategy to minimise the impact of ecological differences and risk of introduction of disease.
26 citations
TL;DR: The results suggest that the genetic architecture underlying the trait and selective pressures acting on the separate morphs of the Gouldian Finch differ between the sexes, but are fairly constant across highly variable environmental conditions.
Abstract: The endangered Gouldian Finch (Erythura gouldiae) possesses a genetic colour polymorphism in the form of three genetically determined head-colours (yellow, black and red) that coexist in the same population. The spatial and temporal pattern of morph ratios within this species provides insight into the selective pressures acting on and maintaining the different forms. To investigate spatial and temporal patterns in the relative historical abundance of the different Gouldian Finch morphs, we surveyed museum collections around the world, identifying 614 wild-caught skins and obtaining accurate data on the morphs of 552 of these. The yellow morph was found at very low numbers (only 15 skins), consistent with its rarity in contemporary populations. Red- and black-morph individuals were found at relatively constant ratios across the geographical range over which they were sampled, and across the 140-year period during which these skins were collected, although this differed slightly for males and females (males: 62.6% black, 37.4% red; females: 79.1% black, 20.9% red). Spatial and temporal stability in the frequency of alternative morphs is extremely rare. These results suggest that the genetic architecture underlying the trait and selective pressures acting on the separate morphs of the Gouldian Finch differ between the sexes, but are fairly constant across highly variable environmental conditions.
25 citations
TL;DR: It is concluded that Palm Cockatoos at Iron Range are unlikely to live for long enough on average to support their low rates of reproduction, and the possibility that the population may be in decline is highlighted.
Abstract: As an order, Parrots (Psittaciformes) are both the longest lived birds and among the most endangered. Palm Cockatoos (Probosciger aterrimus) have an extremely slow life history, including one of the lowest rates of breeding success reported for parrots. Here we use population viability analysis (PVA) to examine whether populations of Palm Cockatoos are viable in the long term with such low rates of reproduction. We built PVA models for two field sites with robust data on reproductive success and availability of nest-hollows: Iron Range on Cape York Peninsula (Queensland, Australia) and Crater Mountain (Eastern Highlands Province, Papua New Guinea). Our Iron Range models incorporate a fluctuating resource base of nest-hollows resulting from natural losses from fire, wind and tree decay and natural replenishment through tree breakages in tropical cyclones. The number of females allowed to breed each year in the simulations was limited by the availability of hollows. Our Iron Range models suggest that the population is only viable if juvenile and adult mortality rates are very low, and that at least some birds in the population live to 100 years old. Based on known maximum lifespans in the Cacatuidae, we conclude that Palm Cockatoos at Iron Range are unlikely to live for long enough on average to support their low rates of reproduction, and highlight the possibility that the population may be in decline. At Crater Mountain, where nestlings are harvested for food by local people, the models suggest that the reported current rate of 40% of nestlings taken is not sustainable.
24 citations
TL;DR: The first population estimates for this period are presented, the new distributional data obtained extend the non-breeding ranges for nine species and it is believed that the Common Redshank is not as widely distributed in eastern China as previously suggested.
Abstract: China is located centrally in the East Asian–Australasian Flyway, and a large proportion of the migratory shorebird population of the Flyway uses its extensive wetlands during migration. However, little is known about the abundance and distribution of shorebirds in China during the non-breeding season. In the non-breeding seasons of 2002–03 to 2006–07 we surveyed shorebirds in coastal and inland areas of eastern China, covering an estimated 2500 km of inland waterways and 3500 km of coastline. We document the abundance and distribution of the main species of shorebirds occurring in the region during the non-breeding season, and present the first population estimates for this period, discuss the accuracy of published population estimates of the Flyway, and describe extensions of range of some species. The total shorebird population in eastern China during the non-breeding season is likely to exceed 1 million birds. There were sufficient data for satisfactory population estimates to be made for six of the 27 different species encountered during the surveys (Pied Avocet, Recurvirostra avosetta; Grey Plover, Pluvialis squatarola; Kentish Plover, Charadrius alexandrinus; Eurasian Curlew, Numenius arquata; Spotted Redshank, Tringa erythropus; and Dunlin, Calidris alpina), and suggestions are made for reviews of the population estimates in the Flyway of four of these species and of the Eurasian Oystercatcher (Haematopus ostralegus), one of the less common species encountered. The new distributional data obtained extend the non-breeding ranges for nine species and it is believed that the Common Redshank (Tringa totanus) is not as widely distributed in eastern China as previously suggested.
TL;DR: The logistic-exposure method is used to model the temporal variation in reproductive success of a neotropical tyrant-flycatcher, the Chapada Flycatcher (Suiriri islerorum), which has been described only recently and raises conservation concerns for this isolated population.
Abstract: The decline of several bird populations has been related to reduced reproductive success. Here we used the logistic-exposure method to model the temporal (age, daily, annual) variation in reproductive success of a neotropical tyrant-flycatcher, the Chapada Flycatcher (Suiriri islerorum), which has been described only recently (2001). We monitored 56 nests, in a reserve in central Brazil, over four seasons from 2003 to 2006. Predation affected 66% of the monitored nests, but varied greatly across years. The probability of daily survival decreased 7% day–1 with the age of the nest and the reproductive success varied greatly between years (16.8, 75.4, 6.7 and 21.4%, 2003–06 respectively). Mean reproductive success (using three analytical methods) ranged from 21 to 25%, but from only 13 to 16% when results from 2004 were excluded. Such low and variable reproductive success is atypical for a neotropical bird. In combination with the small population size and known decline of this population, our findings raise conservation concerns for this isolated population.
TL;DR: This study does not support the notion that hybrid grevilleas have played a causal role in the spread of Noisy Miners across many suburban areas of eastern Australia, but results are consistent with the hypothesis that it is the proliferation of lightly-treed open areas that favours the Noisy Miner.
Abstract: Noisy Miners have been described as a ‘reverse keystone’ species, aggressively excluding many bird species from an ever-increasing range of human-dominated landscapes. Understanding the factors influencing the distribution of Noisy Miners is therefore an important research priority. To determine whether a relationship exists between the distribution of Noisy Miners and the vegetation composition of suburban gardens, birds were surveyed according to a factorial design defined by the presence or absence of grevilleas and eucalypts. Contrary to popular expectation, there was no significant association between the abundance of Noisy Miners and the presence of hybrid grevilleas. However, there was a highly significant relationship between the abundance of Noisy Miners and the presence of eucalypts. Analysis of foraging time budgets showed that Noisy Miners consistently spent 25–30% of their foraging time feeding on grevilleas (only in sites in which they were present). Similar amounts of time were spent foraging in eucalypts or in flowering callistemons (when available), and the presence of grevilleas did not result in a reduction in overall commitments to foraging. Noisy Miners also spent substantial amounts of time foraging on open ground. This study does not support the notion that hybrid grevilleas have played a causal role in the spread of Noisy Miners across many suburban areas of eastern Australia. Our results are consistent with the hypothesis that it is the proliferation of lightly-treed open areas that favours the Noisy Miner.
TL;DR: Blood plasma cholinesterase (ChE) activity is a sensitive indicator of exposure to organophosphorus insecticides in vertebrates and there was a significant difference in all ChE activity between seasons in Zebra Finches.
Abstract: Cholinesterase-inhibiting pesticides are applied throughout Australia to control agricultural pests. Blood plasma cholinesterase (ChE) activity is a sensitive indicator of exposure to organophosphorus insecticides in vertebrates. To aid biomonitoring and provide reference data for wildlife pesticide-risk assessment, plasma acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were characterised in nine species of native bird: King Quails (Excalfactoria chinensis), Budgerigars (Melopsittacus undulatus), White-plumed Honeyeaters (Lichenostomas penicillatus), Yellow-throated Miners (Manorina flavigula), Willie Wagtails (Rhipidura leucophrys), Australian Reed-Warblers (Acrocephalus australis), Brown Songlarks (Cincloramphus cruralis), Double-barred Finches (Taeniopygia bichenovii) and Australasian Pipits (Anthus novaeseelandiae). Plasma ChE activities in all species were within the range of most other avian species and all but one contained AChE and BChE; no AChE was present in King Quail, which has not previously been reported for any species. The lowest detectable plasma AChE activity was 0.10 μmol min–1 mL–1 in Budgerigars and the highest was 0.86 μmol min–1 mL–1 in Australian Reed-Warblers. BChE in the plasma ranged from 0.37 μmol min–1 mL–1 in Double-barred Finches to 0.90 μmol min–1 mL–1 in White-plumed Honeyeaters and Australian Reed-Warblers. The lowest proportion of AChE was found in Budgerigars (12.8%) and highest in Willie Wagtails (67.8%). No differences were detected in ChE activity at any time of day in Budgerigars and Zebra Finches (Taeniopygia guttata), although there was a significant difference in all ChE activity between seasons in Zebra Finches.
TL;DR: This innovative system worked autonomously for 3 days and identified repeat visits by some predators, detected nest predation by Grey Currawong (Strepera versicolor) and two rodents, and provided new insights into nest defence, provisioning rates, vocalisations of parents and nestlings and interactions between them.
Abstract: Effective monitoring techniques are vital to understanding a range of behaviours and their consequences for evolution of life histories. Video and photographic monitoring is regularly used but rarely with audio monitoring even though it can identify birds or predators off-camera, and detect alarm calls and songs. We developed a 4-channel audio-visual recording system to continuously monitor the nests of Superb Fairy-wrens (Malurus cyaneus). This innovative system worked autonomously for 3 days and identified repeat visits by some predators, detected nest predation by Grey Currawong (Strepera versicolor) and two rodents, and provided new insights into nest defence, provisioning rates, vocalisations of parents and nestlings and interactions between them.
TL;DR: Results suggested that both type and size of prey may be important factors permitting food partitioning between the two species of tern during the breeding season.
Abstract: Cayenne (Thalasseus sandvicensis eurygnathus) and Royal Terns (Thalasseus maximus) breed in mixed colonies in Argentina. This paper presents the first detailed information on their breeding diet and assesses differences and overlap between species in the type and size of prey. During 2004 and 2005, observations of prey delivered to mates and chicks were carried out at Punta Leon, Patagonia. The diet of Cayenne and Royal Terns comprised nine and 10 prey species respectively. Fish comprised >99% of the prey of both species of tern in the two study years. Both species had a fairly specialised diet based on pelagic schooling fish, mostly Argentine Anchovy (Engraulis anchoita) and two species of silversides (Odontesthes spp.). Despite observed overlap in trophic resources, our results showed that Argentine Anchovy was the main prey for Royal Terns, whereas the two species of silversides together with Anchovy comprised the bulk of the diet for Cayenne Terns. Fish delivered by Cayenne Terns were significantly smaller than those by Royal Terns. Results suggested that both type and size of prey may be important factors permitting food partitioning between the two species of tern during the breeding season.
TL;DR: It is suggested that neck-collars are suitable for identification of Black Swans, with no differences between collared and uncollared Swans in the percentage time spent resting, swimming or preening.
Abstract: Neck-collars are commonly used to identify geese and swans, but possible adverse effects of collars have been investigated in few species. We evaluated the effects of plastic neck-collars on the be...
TL;DR: It is concluded that the Snares Penguins benefit from stable prey availability as a function of the oceanographic setting of their breeding habitat.
Abstract: Worldwide, crested penguins (Eudyptes spp.) are in decline and it is suspected that reduced prey availability plays an important role. However, the population of Snares Penguins (E. robustus) does not follow this trend, with its population being stable if not slightly increasing. To assess whether the success of the Snares Penguins is a result of a rich and stable prey resource within the breeding range of the species, we examined the dietary composition of breeding Snares Penguins by analysis of stomach contents, and analysed ratios of carbon (δ13C) and nitrogen (δ15N) stable isotopes in feathers of living penguins and historical specimens. The food brought ashore by the Penguins was dominated by a single species of krill, Nyctiphanes australis (~60% of wet weight of the stomach samples); fish (~30%) and cephalopods (~10%) seemed to form only a minor portion. However, numbers of fish otoliths and cephalopod beaks in the samples suggest that these prey classes are more important food source for adult Penguins while at sea. Stable isotope ratios of Snares Penguin feathers collected between 1880 and 2004 revealed no temporal trend in either δ13C or δ15N indicating no significant changes in marine productivity or general composition of the diet of Snares Penguins in the past 120 years. We discuss our findings in the light of declining population trends and changing stable isotope ratios recently detected in Rockhopper Penguins (E. chrysocome), and conclude that the Snares Penguins benefit from stable prey availability as a function of the oceanographic setting of their breeding habitat.
TL;DR: It can be inferred that a population of Night Parrots exists in the region and that this is an encouraging sign that the species is not simply senescing to extinction.
Abstract: We report on a specimen of the Night Parrot (Pezoporus occidentalis) found dead in Diamantina National Park, in western Queensland. It was found on a low dissected tableland near the head of a small creek, in an area vegetated by sparse shrubland of Gidgee (Acacia cambagei), Crimson Turkey Bush (Eremophila latrobei) and Blunt-leaf Cassia (Senna artemisioides var. helmsii). Conditions were dry and the vegetation was not flowering or seeding. It is the second such specimen to be found dead in the region since 1990. The two specimens were found less than 200 km apart. Molecular analysis showed that both specimens are female. The latest specimen appears to be an immature undergoing post-juvenile moult. The specimen confirms a breeding event by Night Parrots in the region less than two years before its discovery in September 2006. Together with the 1990 specimen and other recent reports, it can be inferred that a population of Night Parrots exists in the region and that this is an encouraging sign that the species is not simply senescing to extinction. Diamantina National Park likely provides excellent opportunities to further study the ecology and management requirements of this enigmatic species.
TL;DR: It is believed the application of this method with its high rate of return can be applied to all species of shearwater and will not only assist researchers in future tracking studies but help minimise any adverse effects the logger has on the birds’ behaviour.
Abstract: Recent advances in tracking technology (i.e. smaller and lighter devices) have enabled long deployments, of up to 12 months or more, on shearwaters (Procellariidae). These deployments have been successfully used to examine migration patterns, wintering sites and non-breeding ranges as well as at-sea activity. Hence, an effective method for the long-term deployment of tracking devices that is able to withstand UV radiation, saltwater immersion and terrestrial abrasion while reducing any adverse effects of the attachment of the logger to the bird is needed. Here, a method for attaching global location-sensing (GLS) data-loggers to Short-tailed Shearwaters (Ardenna tenuirostris) on a modified aluminium band is described. GLS loggers were attached for 12 months from the 2007–08 austral summer and 74% of geolocated birds returned the following season compared with a slightly higher rate of 82.5% for birds with no loggers attached. Body mass between birds with and without loggers was not significantly different in the short or long term. No adverse injuries to the birds were observed. We believe the application of this method with its high rate of return can be applied to all species of shearwater and will not only assist researchers in future tracking studies but help minimise any adverse effects the logger has on the birds’ behaviour.
TL;DR: The results of this study confirm the occurrence of White-capped Albatross in this region, expanding its global range and show that it is exposed to pelagic long-line fisheries in this part of the Atlantic.
Abstract: We analyse the interactions of seabirds with the Uruguayan long-line fishing fleet in the south-western Atlantic Ocean, with a focus on White-capped Albatrosses (Thalassarche (cauta) steadi). The aim of this work is to determine the species composition of the incidental by-catch of seabirds and assess the importance (in terms of abundance) of White-capped Albatross in the seabird assemblage attending this fishery. Counts of seabirds associated with fishing vessels (n=132 counts) were made during five commercial fishing trips in Uruguayan waters, and the incidental by-catch of seabirds per line-set (n=44 line-sets) was recorded. Of 25 species of seabird recorded in association with the vessels, five were incidentally caught on long-lines. The relative frequency of occurrence of shy-type albatrosses (cauta-type) observed was 25% and their abundance was in the range 0-20 birds; most birds seen were immatures. The three specimens of shy-type albatrosses caught, along with two other specimens caught by the fleet in 2004, were identified by molecular analysis. All were confirmed to be White-capped Albatrosses, suggesting this species is the predominant one among the shy-type albatrosses occurring in the region. Before this study, there was little information on seabirds for this region of the south-western Atlantic Ocean and it was not included in the distribution of the White-capped Albatross. However, the results of this study confirm its occurrence in this region, expanding its global range and show that it is exposed to pelagic long-line fisheries in this part of the Atlantic.
TL;DR: Results show rapid signalling of carotenoid concentration in the integument that complements the longer term signalling potential of feathers.
Abstract: Carotenoids cannot be synthesised by vertebrates and must be derived from the diet. A growing amount of research has focussed on the role of carotenoids in immune function, as well as the signalling function of carotenoids in the colour of the integument (skin, bill and legs) and feathers. We used an experimental approach to examine the effects of experimental reduction and supplementation of dietary carotenoids on phytohaemagglutinin (PHA) response (as an estimate of cell-mediated immune response) and colour of the bill in the Diamond Firetail (Stagonopleura guttata). To demonstrate the biological relevance of our study, we first show that carotenoid concentrations of our captive experimental birds did not differ significantly from those of wild birds. We found that carotenoids circulating in the plasma of captive Diamond Firetails dropped to 50% of the original concentration in less than 5 days when on a carotenoid-free diet. The mean level of total carotenoids in the plasma stabilised at 6% of the original concentration after 26 days. Finally, Diamond Firetails showed a significant increase in PHA response and increased bill-hue wavelength while on either a lutein or a zeaxanthin supplemented diet. Our results show rapid signalling of carotenoid concentration in the integument (as measured here in the bill) that we suggest complements the longer term signalling potential of feathers.
TL;DR: For example, the authors found that females with yellower crests contained higher concentrations of pigments than those of males in Snares Penguins (Eudyptes robustus) in two years (2002 and 2003) and examined differences in colour and pigment content as a function of year, sex, body size and body condition.
Abstract: Colourful plumages observed in many birds provide ideal systems for investigating the control and function of animal signals, because we can identify the molecular currency (eg pigments, tissue structures) and thus the challenges associated with the production of the trait To date, most attention has been paid to the signalling costs and benefits of the common pigmentary (eg carotenoid- and melanin-based) plumage colours However, in penguins, the colour of feathers of crests or patches of head plumage is based on an unusual fluorescent pigment, presently thought to be in the class of pterin pigments, which are typically found as colourants in other animals like butterflies and amphibians These yellow-orange colours may be used in sexual or social communication, but to date little is known about the signalling potential of such ornaments We collected yellow crest-feathers from adult male and female Snares Penguins (Eudyptes robustus) in two years (2002 and 2003) and examined differences in colour and pigment content as a function of year, sex, body size and body condition Unlike the typical pattern of birds, crests of female Snares Penguins contained higher concentrations of pigments than those of males In both years, yellower feathers in females contained more yellow pigment Birds of both sexes grew yellower and more pigment-rich feathers in 2002 – a year in which birds were in better condition – than in 2003 Males with yellower crests also tended to be larger, heavier and in better condition, regardless of year These results highlight the potential for yellow crests in Snares Penguins to serve as a condition-dependent indicator to conspecifics Further work is needed to determine whether or not this plumage trait is a signal of social status or attractiveness, as colourful plumage patches appear to be in other penguin species
TL;DR: In the absence of Brown Skuas (S. antarcticus), their main prey consists of other birds, such as Chinstrap Penguin (Pygoscelis antarctica) as discussed by the authors.
Abstract: Where South Polar Skuas (Stercorarius maccormicki) occur in the absence of Brown Skua (S. antarcticus), their main prey consists of other birds. In contrast, where the two species occur together, fish appears to dominate the diet of South Polar Skuas, probably because Brown Skuas monopolise the terrestrial resources. Twenty-eight stomach samples of South Polar Skuas were collected throughout the breeding season at Half Moon Island, South Shetland Islands, Antarctica. Fish were the most dominant prey item (100% frequency, 98% prey mass); their importance remained constant throughout the study period. Although there is a colony of Chinstrap Penguin (Pygoscelis antarctica) nearby the South Polar Skua population and there are very few Brown Skuas, the South Polar Skuas did not eat penguins. The result suggests fish are selected preferentially over terrestrial resources, at least in certain regions, and particularly when availability of terrestrial resources is limited. Thus, competitive exclusion by Brown Skuas may not fully explain dietary choice of South Polar Skuas.
TL;DR: The results suggest that the Peterson Creek Revegetation Project will be successful in providing a corridor between formerly isolated forest patches, at least for some species.
Abstract: The success of the Peterson Creek Revegetation Project, near Yungaburra, Queensland, in providing habitat for rainforest-associated birds was monitored for the first seven years of the project from 1999. Regular 20-min area surveys showed that small and large remnants and plantings all differed in their avian communities. Major contributors to these differences were a suite of rainforest-associated birds that were more abundant in the remnants. Ordination showed that avian communities in plantings 4–7 years after their establishment were generally more similar to those in remnants than were the bird communities of younger plantings. Avian communities in the oldest of the planted sites all changed markedly through time and became more similar to the avian communities in the closest remnant sites. Rainforest-associated birds were observed in plantings as early as 1–3 years after their establishment and some rainforest dependent species were observed as early as 3–4 years after establishment. Of the rainforest-associated bird species observed in the remnants, 55% were also recorded in the plantings at some stage during the study. These results suggest that the project will be successful in providing a corridor between formerly isolated forest patches, at least for some species.
TL;DR: It is concluded that some Parakeets were feeding within the petrel colony where they were captured, and that petrel colonies offer foraging opportunities for forest birds but that the birds also use non-colony areas.
Abstract: Where seabird breeding colonies occupy forested habitats, unusual nutrient links between marine and terrestrial ecosystems can occur. In such circumstances, the dietary characteristics of forest birds inhabiting pristine seabird colonies have rarely been investigated. In this study, carried out in a mixed-species colony of petrels (Procellariiformes), we measured the stable isotopic (δ13C, δ15N) signatures of individual feathers of New Zealand Bellbirds (Meliphagidae : Anthornis melanura melanura; n = 6) and Red-crowned Parakeets (Psittacidae : Cyanoramphus novaezelandiae novaezelandiae; n = 15). The δ15N of Parakeet feathers encompassed a wide range, from +7.1‰ to –0.9‰. From the high maximum δ15N, relative to global temperate forest foliage, we conclude that some Parakeets were feeding within the petrel colony where they were captured. However, the low minimum δ15N, relative to foliage from the petrel colony, implies that Parakeet isotopic composition could not be fully explained by potential dietary items from the petrel colony. Bellbird δ15N (range +3.4‰ to +9.6‰) was more enriched than that of Parakeets, consistent with their higher trophic level, but also consistent with a dietary intake consisting of items from both within and beyond the petrel colony. Bellbird isotopic ratios were strongly enriched in δ13C, which could be explained only by consumption of invertebrates with marine isotopic enrichment. The marine invertebrates could have been associated with breeding petrels, or have come from the littoral zone near the site of capture. The importance for both species of food sources both inside and outside of petrel colonies implies that petrel colonies offer foraging opportunities for forest birds but that the birds also use non-colony areas. Consequently, petrel colonies are integral parts of the wider terrestrial landscape which they inhabit.
TL;DR: Understanding the imminent shifts in the structure of wetland plant communities and the likely response of waterfowl populations will focus management on key threats and critical habitat, including identification of important wetlands and the construction of buffers at them to slow salt-water intrusion.
Abstract: We review interactions between waterfowl and wetlands and outline the shifts that are likely to occur within these relationships through global climate change. We highlight the relative paucity of research on populations of tropical waterfowl and their food plants, and use an iconic tropical species of waterfowl, the Magpie Goose (Anseranas semipalmata), as a case study. We provide background on the known and hypothesised interactions between Magpie Geese and wetlands and provide a hypothetical framework of the mechanistic changes to these relationships through climatic change, including rises in sea level, temperature increases, elevated CO2 levels and altered rainfall regimes. Intrusion of saline water through sea-level rise and extended periods of inundation following increased annual rainfall are the two plausible drivers of change in the wetland sedge plants that support Magpie Geese populations. We show how the relative importance of these, and other, threatening factors can be challenged with data from the field and laboratory under multiple working hypotheses. Understanding the imminent shifts in the structure of wetland plant communities and the likely response of waterfowl populations will focus management on key threats and critical habitat. This includes identification of important wetlands and the construction of buffers at them to slow salt-water intrusion.
TL;DR: Blue-fronted Amazons are sexually dimorphic for most characteristics of body size and show sexual dichromatism in the colour of the plumage of the head, which allows determination of sex of individuals by morphological variables that can be easily measured in the field.
Abstract: On current knowledge, it has not been possible to determine the sex of Blue-fronted Amazons (Amazona aestiva) in the hand, as males and females were thought not to differ in the colour of plumage or size. We used discriminant function analysis to develop equations for determining the sex of Blue-fronted Amazons using in-hand measurements. We took seven measurements of size and one measure of plumage colour (percentage of yellow on the head) from 202 birds in north-western Argentina. The sex of each individual was determined using DNA-based genetic techniques. For all size measurements, males averaged larger than females. Males also had a higher percentage of yellow plumage on the head than females. The percentage of yellow plumage (64%) and body mass (12%) had the highest degree of dimorphism, but also showed high within-sex coefficients of variation, correctly classifying 73% and 72% of the individuals respectively. Although bill-depth had a low degree of dimorphism (7%), it had the lowest coefficient of variation (4%) resulting in the most accurate single-measurement for sexing this species (80% of the individuals). A cross validation process revealed that a discriminant function including three measurements (bill-depth, tibial length and head-width) was more accurate and reliable for determination of sex than single measurements, classifying correctly 85% of the individuals. Our results show that Blue-fronted Amazons are sexually dimorphic for most characteristics of body size and show sexual dichromatism in the colour of the plumage of the head, which allows determination of sex of individuals by morphological variables that can be easily measured in the field.
TL;DR: Differences in the spatial arrangement of males, particularly bower density, may explain variation in stealing rates both within and between populations, though alternative explanations, such as differences in resource availability, are also relevant.
Abstract: Competitive interactions between males can affect mate-choice decisions of females, so it is important to understand the factors that underlie variation in the frequency and intensity of male–male interactions. In bowerbirds (Ptilonorhynchidae), two hypotheses have been proposed to explain within- and between-species variation in the rate at which males steal each other’s decorations. Males may steal more frequently as inter-bower distances decrease because this reduces the time and energy costs of travelling between bowers, or they may steal more frequently when bowers contain relatively few decorations, compared with bowers in other populations or species, because this leads to an increase in the value of decorations to males. I compared stealing rates in two populations of Great Bowerbirds (Ptilonorhynchus nuchalis)
in Queensland, Australia, in order to assess these ypotheses. Males at one site, Dreghorn, had fewer decorations, higher nearest-neighbour distances (NND), and fewer males within a 1-km radius of their bowers (termed bower density) than males at the Townsville site. Dreghorn males stole decorations at a lower rate and interacted with fewer individuals, though there was no difference between sites in the rate at which males stole decorations from their nearest neighbours. Within sites, stealing rates were not related to decoration numbers, and partial correlations revealed that stealing rates were correlated with bower density, not NND. These results suggest that differences in the spatial arrangement of males, particularly bower
density, may explain variation in stealing rates both within and between populations, though alternative explanations, such as differences in resource availability, are also relevant.
TL;DR: It was found that body size was significantly correlated withtick prevalence, with larger hosts having higher tick prevalence, and abundance and mean foraging height did not explain the variance in prevalence or intensity of ticks.
Abstract: Ticks are a major vector of disease, so understanding their distribution, geographically and across hosts, is important for the study of evolutionary ecology Numerous passerine species worldwide are infested with ticks, and both prevalence and intensity of ticks vary across host species In bird studies, foraging height is commonly thought to explain the difference in prevalence and intensity of ticks, with ground-foraging birds having a greater chance of encountering a tick In this study, we used phylogenetically independent contrasts to examine the prevalence and intensity of ticks on passerines in South Australia and the role of abundance, body size and host foraging height for differences in prevalence and intensity of ticks We examined 1262 birds for ticks between April 2004 and December 2006 at five sites across South Australia All the ticks we collected were immature life-stages of Ixodes hirsti Of the mist-netted birds, 347 (275%) individuals were infested with an average of 28 ticks Both prevalence and intensity of ticks varied significantly between host species We found that body size was significantly correlated with tick prevalence, with larger hosts having higher tick prevalence Abundance and mean foraging height did not explain the variance in prevalence or intensity of ticks