Data from: Persistent species relationships characterize migrating bird communities across stopover sites and seasons

Global migrations of diverse animal species often converge along the same
routes, bringing together seasonal assemblages of animals that may
compete, prey on each other, and share information or pathogens. These
interspecific interactions, when energetic demands are high and time to
complete journeys is short, may influence survival, migratory success,
stopover ecology, and migratory routes. Numerous accounts suggest
interspecific co-migrations are globally distributed in aerial, aquatic,
and terrestrial systems, although the study of migration to date has
rarely investigated species interactions among migrating animals. Here we
test the hypothesis that migrating animals are communities engaged in
networks of ecological interactions. We leverage over half a million
records of 50 bird species from five bird banding sites collected over
8-23 years to test for species associations using social network analyses.
We find strong support for persistent species relationships across sites
and between spring and fall migration. These relationships may be
ecologically meaningful: they are often stronger among phylogenetically
related species with similar foraging behaviors and non-breeding ranges
even after accounting for the non-social contributions to associations,
including overlap in migration timing and habitat use. While interspecific
interactions could result in costly competition or beneficial information
exchange, we find relationships are largely positive, suggesting limited
competitive exclusion at the scale of a banding station during migratory
stopovers. Our findings support an understanding of animal migrations that
consist of networked communities rather than random assemblages of
independently migrating species, encouraging future studies of the nature
and consequences of co-migrant interactions.