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Combining genomic and field analyses to reveal migratory status in a burrowing owl population

Trulio, Lynne1; Chromczak, Debra2; Higgins, Philip3; Menzel, Sandra3; Bossu, Christen4; Ruegg, Kristen4

Published Jan 08, 2024 on Dryad. https://doi.org/10.5068/D1CT14

Data files

Abstract

Partial migration, in which some members of a population migrate and others do not, is a widely-occurring strategy among animal species, but studies of this behavior are impeded by the difficultly in distinguishing migrant from resident individuals.  We used a combination of genomic sequencing and bird banding to determine the migratory status of individuals in a declining population of western burrowing owls (Athene cunicularia hypugaea) in northern California. We banded individuals for four consecutive years in winter and summer. Each summer we looked for birds we had banded in the winter.  Using genomic analysis, we analyzed feathers from winter birds and birds found in the summer to assess migratory status and interactions between winter and summer birds.  We found a pattern of migration in which birds from outside the region joined resident birds at the breeding sites in the winter, but disappeared by the next breeding season. These results fit the pattern for partial breeding migration.  Although we never observed any individuals in a breeding season that we banded -in winter, genomic analysis showed that small numbers of migrants stayed into the summer and bred with resident birds to produce hybrids between residents and migrants.  This interaction brings different genetic material into the small resident population, a contribution that may benefit this declining population.  This work demonstrates the value of combining genomic assessments of migratory status with careful field measurements to better characterize population structure and inform management actions.