Data for: Post-migratory nonbreeding movements of birds: a review and case study

Seasonal migrations are fascinating and ecologically important, but many
migratory species are declining as climate change and land-use change
alter the habitats used by migrants across the annual cycle. While some
migratory birds use a single wintering site, others undertake large-scale
post-migratory movements during the nonbreeding season. Technological
advances that enable tracking individual birds are uncovering more
examples of post-migratory nonbreeding movements. Documenting these
movements is important for conservation, which requires understanding when
and where migrants use habitats throughout their range. Here, we reviewed
existing literature and collected information on the post-migratory
nonbreeding movements of 92 migratory bird species from 18 orders across
six continents. Among these records, the most commonly reported drivers of
movements were resource availability and climate. This strong dependence
of post-migratory nonbreeding movements on birds’ abiotic and biotic
environments suggests that environmental change will impact the patterns
of these movements and potentially the fitness of species that undertake
them. We also reviewed post-migratory nonbreeding movements in North
American-breeding thrushes from the genus Catharus to examine the drivers
of these movements in five closely related migratory species. We find that
species that are less territorial are more likely to use multiple sites
during the nonbreeding season; however, there is little evidence for
dietary, evolutionary, or environmental differences between thrush species
that move during winter and those that are stationary. While we believe
our study represents the most comprehensive list of species exhibiting
post-migratory nonbreeding movements to date, biases in sampling, a lack
of common terminology for these movements, and the still-nascent
availability of inexpensive, lightweight tracking devices mean that there
are probably many more populations that undertake such movements. Future
research into the consequences of post-migratory nonbreeding movements for
individual fitness and ecosystem services would advance our understanding
of their conservation importance and their evolution.