Across-year social stability shapes network structure in wintering migrant sparrows

Authors

Daizaburo Shizuka, University of Nebraska-LincolnFollow
Alexis S. Chaine, CNRSFollow
Jennifer Anderson, University of California, Santa CruzFollow
Oscar Johnson, Santa Barbara, CAFollow
Inger Marie Laursen, La Selva Beach, CAFollow
Bruce E. Lyon, University of California, Santa CruzFollow

Document Type

Article

Date of this Version

7-2014

Citation

Published in Ecology Letters 17 (2014), pp. 998-1007; doi: 10.1111/ele.12304

Comments

Copyright © 2014 John Wiley & Sons Ltd/CNRS. Used by permission.

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.