Testing for Geographic Variation in Survival of Spectacled Eider (Somateria fischeri) Populations in Chukotka, Russia and the Yukon-Kuskokwim Delta, Alaska

Information on variation in survival among geographically distinct breeding populations can produce valuable insights about the population dynamics of a species. The Yukon-Kuskokwim Delta sub-population of Spectacled Eiders in Alaska decreased precipitously between the 1950s and 1990s. Causes for this decline are unknown but may be attributed to low female survival due to predation and lead exposure on the breeding grounds. From 2014 to 2015, we compared annual survival probabilities of Spectacled Eiders on Kigigak Island in the Yukon-Kuskokwim Delta, Alaska, and Ayopechan Island in the Chaun Delta, Chukotka, where similar field protocols were implemented. A Cormack-Jolly-Seber maximum likelihood approach was used to estimate apparent survival (φ) and recapture probability (p) from mark-resight data. We tested a) whether Russian and Alaskan sub-populations differed in their survival rates, b) whether survival varied annually, and c) whether survival followed an increasing or decreasing trend over time at either site. We found no evidence for differing survival between the two breeding areas when mean survival across years was compared, and we did not find strong evidence for a linear trend in survival over time at either site. Furthermore, our data supported models with annually varying survival at Kigigak Island and constant survival at Ayopechan Island. Sample size constraints precluded estimates of annual survival at Ayopechan Island. Our finding of no difference in mean survival between sites lends support to the idea that survival may be a function of conditions on the wintering grounds.Les données en matière de variations de survie chez des populations nicheuses géographiquement distinctes peuvent donner un précieux aperçu de la dynamique des populations d’une espèce. La sous-population d’eiders à lunettes du delta Yukon-Kuskokwim, en Alaska, a chuté abruptement entre les années 1950 et les années 1990. Nul ne connaît les causes de ce déclin, mais elles pourraient être attribuables au faible taux de survie des femelles en lien avec la prédation et l’exposition au plomb dans les aires de reproduction. De 2014 à 2015, nous avons comparé les probabilités de survie annuelle des eiders à lunettes sur l’île Kigigak, dans le delta Yukon-Kuskokwim, en Alaska, et sur l’île Ayopechan, dans le delta Chaun, au Tchoukotcha, où des protocoles d’étude similaires sur le terrain ont été adoptés. La méthode du maximum de vraisemblance Cormack-Jolly-Seber a servi à estimer la survie apparente (φ) et la probabilité de recapture (p) à partir de données de marquage et de relocalisation. Nous avons tenté de déterminer a) si les sous-populations de la Russie et de l’Alaska avaient des taux de survie différents, b) si les taux de survie variaient d’une année à l’autre et c) si le taux de survie affichait une tendance à la hausse ou à la baisse au fil des ans à l’un ou l’autre des sites. Nous n’avons trouvé aucune preuve justifiant le taux de survie différent aux deux aires de reproduction au moyen de la comparaison des moyennes de survie au fil des ans, et nous n’avons pas trouvé de preuve importante permettant de déceler une tendance linéaire au fil des ans en matière de survie à l’un ou l’autre des deux sites. De plus, nos données ont permis d’étayer des modèles ayant des taux de survie annuels variables à l’île Kigigak et des taux de survie constants à l’île Ayopechan. Des contraintes en matière de taille d’échantillons ont empêché de faire l’estimation des taux de survie annuels à l’île Ayopechan. Le fait que nous n’ayons pas trouvé de différence entre les moyennes de survie des deux sites soutient l’idée selon laquelle la survie peut être tributaire des conditions des aires d’hivernage.Данные об изменении выживаемости в географически обособленных гнездовых популяциях позволяют понять тенденции динамики популяций рассматриваемого вида. В период с 1950-х по 1990-е гг. наблюдалось резкое снижение численности гнездовой популяции очковой гаги в дельте рр. Юкон-Кускоквим, предположительно обусловленное низкой выживаемостью взрослых самок из-за сильного пресса хищников и отравления птиц свинцом в районах гнездования. Мы сравнивали показатели ежегодной выживаемости взрослых самок очковой гаги на о. Кигигак, дельта рр. Юкон-Кускоквим, Аляска, США и на о. Айопечан, дельта рр. Чаун-Пучевеем, Чукотка, Россия. Идентичные полевые протоколы были разработаны и применены в обоих районах исследования. Метод максимального правдоподобия Кормака-Джоли-Себера использовался для оценки ежегодной выживаемости (φ) и вероятности обнаружения (p) птиц по данным повторных отловов. Мы проверяли: а) существование статистически значимых различий в выживаемости самок очковой гаги чукотской и аляскинской популяций в период с 2002 по 2015 гг.; б) межгодовые колебания ежегодной выживаемости; в) наличие тенденций повышения или понижения выживаемости с течением времени в каждой из популяций. Мы не выявили статистически достоверных различий в выживаемости самок из двух районов гнездования, а так же не обнаружили тренда выживаемости со временем ни в одной из популяций. Данные, которыми мы располагаем, позволили оценить ежегодную выживаемость самок на о. Кигигак и, по причине недостатка данных, среднюю межгодовую выживаемость самок на о. Айопечан. Наши выводы о том, что выживаемость самок одинакова в обеих популяциях, позволяют предположить, что на выживаемость очковых гаг в меньшей степени влияют условия гнездовых территорий, чем комплексные условия акватории зимовки

Combining modern tracking data and historical records improves understanding of the summer habitats of the Eastern Lesser White‐fronted Goose Anser erythropus

Abstract: The Lesser White‐fronted Goose (Anser erythropus), smallest of the “gray” geese, is listed as Vulnerable on the IUCN Red List and protected in all range states. There are three populations, with the least studied being the Eastern population, shared between Russia and China. The extreme remoteness of breeding enclaves makes them largely inaccessible to researchers. As a substitute for visitation, remotely tracking birds from wintering grounds allows exploration of their summer range. Over a period of three years, and using highly accurate GPS tracking devices, eleven individuals of A. erythropus were tracked from the key wintering site of China, to summering, and staging sites in northeastern Russia. Data obtained from that tracking, bolstered by ground survey and literature records, were used to model the summer distribution of A. erythropus. Although earlier literature describes a patchy summer range, the model suggests a contiguous summer habitat range is possible, although observations to date cannot confirm A. erythropus is present throughout the modeled range. The most suitable habitats are located along the coasts of the Laptev Sea, primarily the Lena Delta, in the Yana‐Kolyma Lowland, and smaller lowlands of Chukotka with narrow riparian extensions upstream along major rivers such as the Lena, Indigirka, and Kolyma. The probability of A. erythropus presence is related to areas with altitude less than 500 m with abundant wetlands, especially riparian habitat, and a climate with precipitation of the warmest quarter around 55 mm and mean temperature around 14°C during June‐August. Human disturbance also affects site suitability, with a gradual decrease in species presence starting around 160 km from human settlements. Remote tracking of animal species can bridge the knowledge gap required for robust estimation of species distribution patterns in remote areas. Better knowledge of species' distribution is important in understanding the large‐scale ecological consequences of rapid global change and establishing conservation management strategies

The effect of climate change on avian offspring production: A global meta-analysis

Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations. A total of 56.7% of populations showed a declining trend in offspring production (significant in 17.4%), whereas 43.3% exhibited an increase (significant in 10.4%). The results show that climatic changes affect offspring production through compounded effects on ecological and life history traits of species. Migratory and larger-bodied species experienced reduced offspring production with increasing temperatures during the chick-rearing period, whereas smaller-bodied, sedentary species tended to produce more offspring. Likewise, multi-brooded species showed increased breeding success with increasing temperatures, whereas rising temperatures were unrelated to repro- ductive success in single-brooded species. Our study suggests that rapid declines in size of bird populations reported by many studies from different parts of the world are driven only to a small degree by changes in the production of young

Geolocator tagging of east Siberian Bluethroats

The Bluethroat subspecies Cyanecula svecica svecia occurs throughout the northern Palearctic. European C. s. svecia has been shown to follow a route west of the Himalaya to winter quarters in southern Asia. Out of 30 Bluethroats tagged with geolocators in eastern Siberia, we obtained one track suggesting that it migrated east of the Himalaya to a wintering area located in Myanmar. The different routes of western and eastern C. s. svecia implicate the presence of a migratory divide in Siberia, either formed in situ during the post-glacial colonization process or resulting from a secondary contact between different refuge populations

Use of geolocators reveals previously unknown Chinese and Korean scaly-sided merganser wintering sites

We determined, for the first time, individual linkages between breeding areas of nesting female scaly-sided mergansers Mergus squamatus in the Russian Far East and their previously unknown wintering grounds in coastal Korea and inland China. Geolocators were deployed on nesting females caught and recaptured on nests along a 40-km stretch of the Kievka River. Mean positions for brood-rearing females during the summer were on average within 61.9 km of the nest site, suggesting reasonable device accuracy for subsequent location of winter quarters. Geolocation data showed that most birds wintered on freshwater habitats throughout mainland China, straddling an area 830 km E−W and 1100 km N−S. Most wintered in discrete mountainous areas with extensive timber cover, large rivers and low human population density. Three birds tracked in more than one season returned to within 25−150 km of previous wintering areas in successive years, suggesting winter fidelity to catchments if not specific sites. A single female from the adjacent Avvakumovka catchment wintered on saltwater in Korea, at least 1300 km east of Chinese wintering birds. Most sea duck species (Tribe Mergini) form pairs away from breeding areas, suggesting that this high level of winter dispersal amongst close-nesting females is a potential mechanism to maintain gene flow in this threatened species that has specialist habitat requirements. Hence, female scaly-sided mergansers disperse widely from breeding areas, but show fidelity to nesting areas and winter quarter

Shrub-dwelling species are joining the Arctic passerine bird community in the Chaun Delta (Western Chukotka, Russia)

Avian communities play a pivotal role in Arctic ecosystems and birds have become the key model taxa for climate change research. Due to funding priorities, Arctic passerines have been studied less intensively than waterfowl and shorebirds. In our study, we aim to partly fill this gap and look at the change in passerine community species composition in the Chaun River Delta in Northeast Siberia (68.81° N, 170.62° E) between 1970–1980 and 2002–2019. We restricted our comparison to 16 tundra-dwelling species associated with grass and shrub tundra habitats. During the first period, 12 passerine species were reported and by the end of the last period, 14 species. Our observations show that four species of shrub-dwelling passerines, the Dusky Warbler (Phylloscopus fuscatus), two species of Turdus thrushes, and the Siberian Rubythroat (Calliope calliope), have joined the local community. Additionally, one Turdus thrush species increased in numbers. The only passerine species that used to be common in the 70’s and rare in the 2000s is the Lapland Bunting (Calcarius lapponicus). Yellow-breasted Bunting (Emberiza aureola, vagrant in 70’s) and Siberian Chiffchaff (Phylloscopus tristis, rare breeder in 70’s) have not been recorded during the most recent period. At the same time, there was no observed change in abundance for eight species of songbirds. The results of supervised satellite image classification did not detect any local-scale increase of shrub cover in our study site. However, a broad-scale assessment of vegetation change using NDVI suggests substantial greening or ‘shrubification’ across the region. We speculate that it promotes region-wide increases and range expansion of some shrub-dwelling species, recorded in our study

Phenotypic and genetic characterization of the East Siberian Willow Warbler (Phylloscopus trochilus yakutensis Ticehurst, 1935) in relation to the European subspecies

Long-distance migrants with transcontinental breeding ranges are of particular interest for the study of local adaptation and geographic differentiation in birds. We compared phenotypes and genotypes between Far East Siberian Willow Warblers Phylloscopus trochilus yakutensis Ticehurst, 1935 with the European subspecies P. t. trochilus Linnaeus, 1758 and P. t. acredula Linnaeus, 1758. We found significant differences in mean body size and plumage colour, but intra-population variation overlapped extensively between the European and Siberian populations. We used stable isotope composition in winter-grown flight feathers as a proxy for wintering sites and found differences between all three subspecies, indicating different wintering grounds. Out of four nuclear loci analyzed (three of which are known to be substantially divergent between the European subspecies), none allowed to seperate East Siberian yakutensis from North Scandinavian acredula. Hence, neither phenotypic traits nor the currently available genetic resources provide diagnostic criteria for confidently assigning individual Willow Warblers to a particular subspecies. Despite extensive overlap in phenotypes and genotypes, we propose that the subspecies names can still be used as biogeographical references to the three Willow Warbler populations that differ in migration strategies. We propose to use yakutensis for Willow Warblers breeding east of the Ural Mountains that presumably initiate autumn migration towards the southwest or west, in contrast to the genetically most similar acredula that start autumn migration towards the southeast or south. Future field studies are needed to elucidate whether the longitudinal variation in phenotype is a cline, or whether a clear contact zone between these subspecies can be identified

Combining stable hydrogen (δ2H) isotopes and geolocation to assign Scaly-sided Mergansers to moult river catchments

Scaly-sided Mergansers Mergus squamatus breed on freshwater rivers in Far East Russia, Korea, and China, wintering on similar habitat in China and Korea, but information on their post-breeding moulting habitats remains elusive. We combined analysis of stable hydrogen isotope ratios (δ2H) in flight feathers from nesting females equipped with geolocators to test whether we could correctly identify their use of moulting rivers (which show a strong north–south gradient in river water δ2H characteristics) based on feather δ2H values. The results are the first ever to demonstrate a strong positive correlation (r 2 = 0.91) between measured river catchment water δ2H and feather δ2H from birds of known moulting location (from geolocation) in an avian piscivorous species. Furthermore, our δ2H results overwhelmingly supported previous determinations based on feather δ13C and δ15N measurements from the same individuals confirming that most Scaly-sided Mergansers of both sexes moulted on freshwater, although four non-breeding and failed breeding females (out of 21) and one male (out of six) apparently undertook moult migration to brackish and marine waters. The single case where the δ2H results contradicted previous isotopic evidence was likely due to birds eating migratory fish of marine provenance that migrate up freshwater rivers. These results confirm the potential power of feather δ2H to assign piscivorous birds to specific river catchment moult sites and the utility of using multiple stable isotopes to assign birds to moult habitat and location in potentially complex estuarine and brackish situations or where migratory prey may be used by birds in freshwater habitat

Combining modern tracking data and historical records improves understanding of the summer habitats of the Eastern Lesser White-fronted Goose Anser erythropus

The Lesser White-fronted Goose (Anser erythropus), smallest of the “gray” geese, is listed as Vulnerable on the IUCN Red List and protected in all range states. There are three populations, with the least studied being the Eastern population, shared between Russia and China. The extreme remoteness of breeding enclaves makes them largely inaccessible to researchers. As a substitute for visitation, remotely tracking birds from wintering grounds allows exploration of their summer range. Over a period of three years, and using highly accurate GPS tracking devices, eleven individuals of A. erythropus were tracked from the key wintering site of China, to summering, and staging sites in northeastern Russia. Data obtained from that tracking, bolstered by ground survey and literature records, were used to model the summer distribution of A. erythropus. Although earlier literature describes a patchy summer range, the model suggests a contiguous summer habitat range is possible, although observations to date cannot confirm A. erythropus is present throughout the modeled range. The most suitable habitats are located along the coasts of the Laptev Sea, primarily the Lena Delta, in the Yana-Kolyma Lowland, and smaller lowlands of Chukotka with narrow riparian extensions upstream along major rivers such as the Lena, Indigirka, and Kolyma. The probability of A. erythropus presence is related to areas with altitude less than 500 m with abundant wetlands, especially riparian habitat, and a climate with precipitation of the warmest quarter around 55 mm and mean temperature around 14°C during June-August. Human disturbance also affects site suitability, with a gradual decrease in species presence starting around 160 km from human settlements. Remote tracking of animal species can bridge the knowledge gap required for robust estimation of species distribution patterns in remote areas. Better knowledge of species' distribution is important in understanding the large-scale ecological consequences of rapid global change and establishing conservation management strategies

Contrasting habitat use and conservation status of Chinese-wintering and other Eurasian Greater White-fronted Goose (Anser albifrons) populations

BackgroundGPS/GSM tracking data were used to contrast use of (i) habitats and (ii) protected areas between three Arctic-nesting Greater White-fronted Geese (Anser albifrons, GWFG) populations throughout the annual cycle. We wished to demonstrate that the East Asian Continental Population (which winters on natural wetlands in the Chinese Yangtze River floodplain and is currently declining) avoids using farmland at multiple wintering sites. We also gathered tracking evidence to support general observations from two increasing population of GWFG, the North Sea-Baltic (which winters in Europe) and the West Pacific (which winter in Korea and Japan) winter mostly within farmland landscapes, using wetlands only for safe night roosts.MethodsWe tracked 156 GWFG throughout their annual cycle using GPS/GSM transmitters from these three populations to determine migration routes and stopover staging patterns. We used Brownian Bridge Movement Models to generate summer, winter and migration stopover home ranges which we then overlaid in GIS with land cover and protected area boundary at national level to determine habitat use and degree of protection from nature conservation designated areas.ResultsData confirmed that 73% of European wintering GWFG homes ranges were from within farmland, compared to 59% in Japan and Korea, but just 5% in China, confirming the heavy winter use of agricultural landscapes by GWFG away from China, and avoidance of farmland at multiple sites within the Yangtze River floodplain. The same GWFG used farmland in northeast China in spring and autumn, confirming their experience of exploiting such habitats at other stages of their annual cycle. Chinese wintering birds showed the greatest overlap with protected areas of all three populations, showing current levels of site safeguard are failing to protect this population.ConclusionsResults confirm the need for strategic planning to protect the East Asian Continental GWFG population. While the site protection network in place to protect the species seems adequate, it has failed to stop the declines. Buffalo grazing could serve as one simple strategy to improve the condition of feeding habitats at Dongting Lake and Poyang Lake in the Yangtze, where vast Carex meadows exist. In addition, while we warn against pushing GWFG to winter farmland feeding in China because of the long-term potential to conflict with agricultural interests, we recommend experimental sacrificial, disturbance-free farmland within designated refuge areas adjacent to the Yangtze River floodplain wetland reserves as a manipulative experiment to improve the conservation status of this population in years when natural food sources are limited.publishe