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

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.