Social determinants of songbird vocal activity and implications for the persistence of small populations

Abstract

AbstractConspecific attraction is an important aspect of animal behaviour and several avian studies have shown that vocalizations may be used as an inadvertent cue to locate areas of suitable habitat. By studying the metapopulation system of a territorial passerine, the Dupont's lark Chersophilus duponti, we analysed the demographic correlates of population vocal activity, and the relationships between the occurrence of immigration and the availability of social information (e.g. vocal activity, population size, density and productivity) in 22 local populations. We found that the proportion of active singing days in spring and territorial call advertisement after breeding were positively related to the number of males within local populations. In turn, the intensity of vocal activity was associated with the likelihood of receiving immigrants, better explaining immigration than other kinds of social or public information. Because of depressed signalling, small local populations could experience reduced rescuing from others, thus compromising population persistence. In such cases, habitat management alone may not be enough to overcome this behavioural constraint. Because we found that the occurrence of inter‐patch movements also depended on the size of nearby local populations, understanding regional processes may be as important as controlling social and environmental factors for the maintenance of small populations.