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Data from:Using a large citizen science dataset to uncover diverse patterns of elevational migration in Himalayan birds

Menon, Tarun1; Elsen, Paul R.2; Srinivasan, Umesh1

Published May 22, 2025 on Dryad. https://doi.org/10.5061/dryad.9cnp5hqvm

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Abstract

Elevational migration is well-documented in montane birds, yet large-scale patterns outside the Americas remain understudied. Using eBird data, we analysed the elevational ranges of 377 Himalayan bird species across breeding and non-breeding periods. We describe five elevational migration patterns which broadly include post-breeding upslope and downslope migration. Most high elevation breeders (65-75%) were downslope migrants, which were further subdivided into four distinct patterns: “displace”, “shift”, “expand”, and “contract”. Notably, 30% of species show partial migration (expand and contract). The same species often show different migration patterns in the eastern and western Himalayas indicating significant intraspecific variation, determined by local biotic and abiotic conditions. Specialised dietary guilds like invertivores were more likely to show shift or displace migration, potentially tracking seasonally fluctuating food resources. Generalists like omnivores and human commensals were more likely to be resident. Species found in open habitats were also more likely to show shift and displace migration, as open habitats have more pronounced exposure to adverse climate conditions which many species are unable to withstand. Territorial birds were largely non-migratory, most likely to retain high quality breeding territories. These migration patterns, shaped by the bounded nature of mountain ranges is useful for understanding elevational migration globally.