title: Across-year social stability shapes network structure in wintering migrant sparrows.
abstract: Migratory birds often form flocks on their wintering grounds, but important details of social structure such as the patterns of association between individuals are virtually unknown. We analysed networks of co-membership in short-term flocks for wintering golden-crowned sparrows (Zonotrichia atricapilla) across three years and discovered social complexity unsuspected for migratory songbirds. The population was consistently clustered into distinct social communities within a relatively small area (~ 7 ha). Birds returned to the same community across years, with mortality and recruitment leading to some degree of turnover in membership. These spatiotemporal patterns were explained by the combination of space use and social preference - birds that flocked together in one year flocked together again in the subsequent year more often than were expected based on degrees of home range overlap. Our results suggest that a surprising level of social fidelity across years leads to repeatable patterns of social network structure in migratory populations.
authors.affiliation: School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
authors.forename: Daizaburo
authors.initials: D
authors.lastname: Shizuka
authors.forename: Alexis S
authors.initials: AS
authors.lastname: Chaine
authors.forename: Jennifer
authors.initials: J
authors.lastname: Anderson
authors.forename: Oscar
authors.initials: O
authors.lastname: Johnson
authors.forename: Inger Marie
authors.initials: IM
authors.lastname: Laursen
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Lyon
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D011157:Population Dynamics; D012621:Seasons; D046370:Sparrows / Q000502:physiology*
keywords: Flocks; MRQAP; group living; social networks; spatial communities; temporal stability; winter ecology