Migratory divides, where individuals from distinct breeding populations within a species exhibit divergent migratory routes and strategies, play a critical role in shaping avian ecology and evolution. These divides can drive intraspecific genetic divergence and promote reproductive isolation, potentially leading to population differentiation and speciation. Understanding the migration strategies of populations utilizing distinct flyways is essential not only for elucidating the mechanisms underlying migration patterns but also for informing effective species conservation efforts. From 2014 to 2023, we used satellite tracking to monitor the migration patterns of 87 White-naped Cranes ( Antigone vipio ) from the species' two breeding populations—western (Mongolia) and eastern (Songnen Plain, China). We delineated their migratory routes, quantified key migration parameters, and identified their population- and season-specific differences in migratory strategies. Our results indicate that the Greater Khingan Mountains and the Bohai-Yellow Sea formed a distinct migratory barrier separating the eastern and western populations. Significant differences in migration strategies were observed between populations and seasons. The western population adopts a “longer-distance, slower-speed, more-stopover” strategy, while the eastern population employs a “shorter-distance, higher-speed, fewer-stopover” strategy. Our study identifies the migratory divides between the two populations of White-naped Cranes and highlights the importance of migratory divides in shaping distinct migration strategies. These findings enhance our understanding of the factors driving population-specific migration strategies and provide a foundation for tailored conservation efforts for these populations.

Climate change is altering vegetation phenology, differentially affecting food quality and availability for the gosling development (and therefore fitness) of migratory herbivores, especially those experiencing range contraction and fragmentation. By quantifying the climate-vegetation nexus for two waterbird species of contrasting conservation status, we assessed the differential implications of climate change in semi-arid landscapes for gosling development windows in different parts of their mid-latitude breeding ranges. We defined breeding ranges using telemetry data from 663 summering tracks of tagged Swan Geese ( Anser cygnoides ) and Greylag Geese ( A. anser ) breeding across the Mongolian Plateau. Within these areas, we systematically analyzed spatiotemporal variations in vegetation phenology based on MODIS NDVI datasets from 2000 to 2024 and their response to climate factors. Combining the above data, we demonstrated synchrony between goose breeding phenology and vegetation phenological indices: gosling hatching coincided with the start of growing season (SOS), autumn migration initiation with the end of growing season (EOS). We determined temporal and geographical variation in vegetation SOS, EOS and the length of growing season (LOS = EOS − SOS) as a proxy for gosling development windows across the Mongolian Plateau. Mean LOS was 107 ± 13 days, generally sufficient for gosling development (c. 113 days), but showed spatial heterogeneity, increasing in the west but shortening in the east of Mongolian Plateau. SOS was delayed with higher land surface temperature and lower precipitation/aridity in central/eastern Mongolian Plateau, but advanced in the west. Elevation of these three climatic factors delayed EOS across Mongolian Plateau. Climate warming and hydric stress may trigger synergistic SOS-delay and EOS-advance effects in the central and eastern Mongolian Plateau, increasing differential phenological mismatch risks to offspring fitness, thereby potentially affecting population growth rates and distributions. • MP Geese breeding synced with vegetation: hatching-SOS, migration-EOS. • LOS sufficed for gosling development, increasing west but shortening east MP. • SOS was delayed by +temp/-aridity in central and east, positively in west. • EOS positively correlated with all three climatic factors. • Warming caused SOS delays/EOS advances in east MP, risking goslings.

Great Snipe ( Gallinago media ) is a shorebird which has a Near Threatened status on the global scale. However, little is known about its migration strategy from the breeding range in Russia. This study is the first one aiming to reveal migration routes, stopovers and wintering grounds of adult Great Snipes from their breeding range in Russia using GPS devices. We also analyzed connectivity of Great Snipes from different breeding populations of this species during non-breeding season. In 2021, we equipped seven males and three females with satellite transmitters, ICARUS Basic Tags, in the breeding range in central European Russia (56°41′ N, 37°59′ E). One female appeared later in tundra of north-eastern Europe. In the second half of July – early September, birds migrated to Africa in a fairly wide front and made stopovers in Europe before crossing seas and the Sahara. Our data allowed to suppose high mortality of birds on migration, especially during the trans-Saharan flight. Only four Great Snipes reached Africa alive during southward migration. These birds spread over across wide area from Eritrea to Ghana after the trans-Saharan flight, after which they moved in a general westward direction and made final prolonged stopovers in Ghana or to the south of Chad Lake. In October/December birds relocated to wintering grounds in Sub-Equatorial Afrotropics as far as the south of Democratic Republic of the Congo and Zambia; with intermediate winter sites in low and middle reaches of the Congo Basin. Together with other published results, our data showed wide overlap of African non-breeding grounds of birds coming from lowland Eastern European and mountain Scandinavian breeding populations. The results also indicated insufficient conservation status of migration stopovers and wintering sites, used by Great Snipes, and demonstrated high importance of West Africa for conservation of this species.

Urbanization has profoundly reshaped biodiversity, yet its impacts on community seasonal changes remain poorly understood. Here, we used citizen science data from 839 bird species in 37 cities and their corresponding rural areas in China to assess how urbanization alters seasonal changes in bird communities. We calculated Sørensen beta dissimilarity indices ( β sor ) between seasons to compare the seasonality of communities in urban and rural areas and decomposed these indices into turnover ( β sim ) and nestedness ( β nes ) components. We evaluated whether there are differences in the latitudinal clines in community seasonality between urban and rural areas, and explored whether environmental and socio-economic factors affect the urbanization-driven changes in community seasonality. Our results show that the overall seasonal β sor in urban communities was 16.2% higher than in rural areas, due to a 49.5% increase in β nes (urban: 0.22 ± 0.12 vs. rural: 0.15 ± 0.08), but there was no significant difference in β sim. In rural areas, β sor increased with latitude, but β sor showed no latitudinal trend in urban communities. Human population emerges as a key predictor of urbanization-driven changes in the species turnover and nestedness components, with larger cities showing lower species turnover but higher nestedness components. We conclude that urbanization alters the seasonality of bird communities through nestedness components, decouples the relationship between community seasonality and latitude, and concentrates its impacts in densely populated cities. Future research must employ long-term monitoring to track how urbanization changes bird communities in space and time. • Urbanization altered the seasonality of bird communities through nestedness components in China. • Urbanization decoupled the latitudinal gradients in avian community seasonality. • Larger cities showed lower species turnover of community seasonality but higher nestedness components.