Simeon Lisovski

Body shrinkage due to Arctic warming reduces red knot fitness in tropical wintering range

Consequences conferred at a distance Migratory animals have adapted to life in multiple, sometimes very different environments. Thus, they may show particularly complex responses as climates rapidly change. Van Gils et al. show that body size in red knot birds has been decreasing as their Arctic breeding ground warms (see the Perspective by Wikelski and Tertitski). However, the real toll of this change appears not in the rapidly changing northern part of their range but in the apparently more stable tropical wintering range. The resulting smaller, short-billed birds have difficulty reaching their major food source, deeply buried mollusks, which decreases the survival of birds born during particularly warm years. Science, this issue p. 819; see also p. 775 A warming Arctic decreases the fitness of migratory red knots in their distant wintering range. Reductions in body size are increasingly being identified as a response to climate warming. Here we present evidence for a case of such body shrinkage, potentially due to malnutrition in early life. We show that an avian long-distance migrant (red knot, Calidris canutus canutus), which is experiencing globally unrivaled warming rates at its high-Arctic breeding grounds, produces smaller offspring with shorter bills during summers with early snowmelt. This has consequences half a world away at their tropical wintering grounds, where shorter-billed individuals have reduced survival rates. This is associated with these molluscivores eating fewer deeply buried bivalve prey and more shallowly buried seagrass rhizomes. We suggest that seasonal migrants can experience reduced fitness at one end of their range as a result of a changing climate at the other end.

Variable detours in long-distance migration across ecological barriers and their relation to habitat availability at ground.

Migration detours, the spatial deviation from the shortest route, are a widespread phenomenon in migratory species, especially if barriers must be crossed. Moving longer distances causes additional efforts in energy and time, and to be adaptive, this should be counterbalanced by favorable condition en route. We compared migration patterns of nightingales that travelled along different flyways from their European breeding sites to the African nonbreeding sites. We tested for deviations from shortest routes and related the observed and expected routes to the habitat availability at ground during autumn and spring migration. All individuals flew detours of varying extent. Detours were largest and seasonally consistent in western flyway birds, whereas birds on the central and eastern flyways showed less detours during autumn migration, but large detours during spring migration (eastern flyway birds). Neither migration durations nor the time of arrival at destination were related to the lengths of detours. Arrival at the breeding site was nearly synchronous in birds flying different detours. Flying detours increased the potential availability of suitable broad-scale habitats en route only along the western flyway. Habitat availability on observed routes remained similar or even decreased for individuals flying detours on the central or the eastern flyway as compared to shortest routes. Thus, broad-scale habitat distribution may partially explain detour performance, but the weak detour-habitat association along central and eastern flyways suggests that other factors shape detour extent regionally. Prime candidate factors are the distribution of small suitable habitat patches at local scale as well as winds specific for the region and altitude.

An unknown migration route of the ‘globally threatened’ Aquatic Warbler revealed by geolocators

AbstractThe globally-threatened Aquatic Warbler (Acrocephalus paludicola) breeds in Europe and spends the northern winter in sub-Saharan West Africa. We attached 30 geolocators to breeding birds in the central Ukraine in 2010. Three geolocators which collected data from the autumn migration were recovered in 2011. They revealed a previously-unknown migration route via southern Europe to stopover sites in south-western France and Spain. In West Africa, one bird spent some time well south of known non-breeding areas. For the conservation of some Aquatic Warbler populations, protection of hitherto unknown stopover sites in southern Europe and Africa may be crucial.ZusammenfassungGeolokation deckt unbekannten Zugweg des global bedrohten Seggenrohrsängers auf. Der global bedrohte Seggenrohrsänger (Acrocephalus paludicola) brütet in Europa und überwintert in Westafrika. Wir rüsteten 2010 30 Seggenrohrsänger in einem Brutgebiet in der Zentral-Ukraine mit Geolokatoren aus. Drei Geolokatoren, die Daten vom Herbstzug aufnahmen, wurden 2011 zurückgewonnen. Sie zeigten einen bis dahin unbekannten Zugweg der Seggenrohrsänger durch Südeuropa zu den ersten Hauptrastgebieten in Südfrankreich und Spanien an. In Westafrika hielt sich ein Vogel weit südlich der bekannten Überwinterungsgebiete auf. Für den Schutz der Seggenrohrsänger könnte es daher bedeutend sein, die noch unbekannten Rastgebiete in Südeuropa und Afrika zu berücksichtigen.

Movement patterns of Sanderling (Calidris alba) in the East Asian–Australasian Flyway and a comparison of methods for identification of crucial areas for conservation

Abstract Worldwide, most populations of migratory shorebirds are in jeopardy, none more so than those of the East Asian—Australasian Flyway (EAAF). In order to preserve these highly mobile species a detailed understanding of their use of feeding and resting sites along the flyway is required. In this study we used light-level geolocators and new analytical tools to reveal individual breeding locations and migration routes of 13 Sanderlings (Calidris alba) that spend their non-breeding season in South Australia. We then used these individual migration routes to identify the timing and location of important stopping areas and compared this with assessments based on resightings of leg-flagged birds and count data. During both northward and southward migration, Sanderlings were found to make extensive use of five main areas of the Chinese coastline, the Yellow Sea and the northern end of the Sakhalin Peninsula. Insights gained from the individual migration routes highlight inherent biases in using only count and resighting data to identify important feeding and resting sites along the Flyway. These findings suggest that data on individual movements may be crucial to effective conservation planning of shorebirds in the EAAF and elsewhere in the world.

Avian influenza in Australia : a summary of 5 years of wild bird surveillance

BACKGROUND Avian influenza viruses (AIVs) are found worldwide in numerous bird species, causing significant disease in gallinaceous poultry and occasionally other species. Surveillance of wild bird reservoirs provides an opportunity to add to the understanding of the epidemiology of AIVs. METHODS This study examined key findings from the National Avian Influenza Wild Bird Surveillance Program over a 5-year period (July 2007-June 2012), the main source of information on AIVs circulating in Australia. RESULTS The overall proportion of birds that tested positive for influenza A via PCR was 1.9 ± 0.1%, with evidence of widespread exposure of Australian wild birds to most low pathogenic avian influenza (LPAI) subtypes (H1-13, H16). LPAI H5 subtypes were found to be dominant and widespread during this 5-year period. CONCLUSION Given Australias isolation, both geographically and ecologically, it is important for Australia not to assume that the epidemiology of AIV from other geographic regions applies here. Despite all previous highly pathogenic avian influenza outbreaks in Australian poultry being attributed to H7 subtypes, widespread detection of H5 subtypes in wild birds may represent an ongoing risk to the Australian poultry industry.

MHC diversity and female age underpin reproductive success in an Australian icon; the Tasmanian devil

Devil Facial Tumour Disease (DFTD), a highly contagious cancer, has decimated Tasmanian devil (Sarcophilus harrisii) numbers in the wild. To ensure its long-term survival, a captive breeding program was implemented but has not been as successful as envisaged at its launch in 2005. We therefore investigated the reproductive success of 65 captive devil pair combinations, of which 35 produced offspring (successful pairs) whereas the remaining 30 pairs, despite being observed mating, produced no offspring (unsuccessful pairs). The devils were screened at six MHC Class I-linked microsatellite loci. Our analyses revealed that younger females had a higher probability of being successful than older females. In the successful pairs we also observed a higher difference in total number of heterozygous loci, i.e. when one devil had a high total number of heterozygous loci, its partner had low numbers. Our results therefore suggest that devil reproductive success is subject to disruptive MHC selection, which to our knowledge has never been recorded in any vertebrate. In order to enhance the success of the captive breeding program the results from the present study show the importance of using young (2-year old) females as well as subjecting the devils to MHC genotyping.

Sex-Specific Arrival Times on the Breeding Grounds: Hybridizing Migratory Skuas Provide Empirical Support for the Role of Sex Ratios

In migratory animals, protandry (earlier arrival of males on the breeding grounds) prevails over protogyny (females preceding males). In theory, sex differences in timing of arrival should be driven by the operational sex ratio, shifting toward protogyny in female-biased populations. However, empirical support for this hypothesis is, to date, lacking. To test this hypothesis, we analyzed arrival data from three populations of the long-distance migratory south polar skua (Catharacta maccormicki). These populations differed in their operational sex ratio caused by the unidirectional hybridization of male south polar skuas with female brown skuas (Catharacta antarctica lonnbergi). We found that arrival times were protandrous in allopatry, shifting toward protogyny in female-biased populations when breeding in sympatry. This unique observation is consistent with theoretical predictions that sex-specific arrival times should be influenced by sex ratio and that protogyny should be observed in populations with female-biased operational sex ratio.