Meeting Abstract

60.3  Thursday, Jan. 6  Analyzing the Costs and Benefits of Vocal Matching in Budgerigars: a Test of the Password Hypothesis YOUNG, A.M.*; WRIGHT, T.F.; New Mexico State University; New Mexico State University annay@nmsu.edu

In budgerigars (Melopsittacus undulatus), vocal matching of an immigrant bird’s contact call to that of its new flock has been experimentally demonstrated, but the costs and benefits of this matching behavior have not been investigated. We simulated immigration in captive flocks of budgerigars to test two predictions of the password hypothesis: 1) that there is a social cost to immigrant birds that do not produce the shared flock call in the form of aggression and exclusion, and 2) these costs are alleviated once the immigrant imitates the shared call of the flock. We experimentally manipulated the membership of captive flocks of budgerigars, then recorded contact calls and behavior and analyzed glucocorticoid metabolites in feces as an indicator of stress levels. Transfer to a new group appears to cause transitory stress in immigrants, but contrary to predictions of the password hypothesis, stress hormones return to baseline levels before vocal matching to the flock occurs, and transfer recruits are not subject to more aggression than control recruits. Call types can be shared not just at the flock level, but also between two or more birds, with some birds possessing seven or more call types that can be highly variable. These findings call into question the assumptions underlying the password hypothesis, namely that group membership is exclusive and costly. Patterns of vocal matching suggest that budgerigars use different shared vocalizations to reference both specific individuals and groups; this may function to establish the sender-receiver relationship in complex fission-fusion societies and enhance cohesion at the flock, sub-flock, and mate level.