Pair duets in the yellow-naped amazon (Psittaciformes : Amazona auropalliata): Responses to playbacks of different dialects

Yellow-naped amazons, Amazona auropalliata, have regional dialects in which several functional classes of vocalization, including contact calls and pa ir duets, change their acoustic structure at the same geographic boundaries . Here we examine the responses of 11 pairs of yellow-naped amazons to play backs of duets from other pairs nesting near the same roost, other roosts w ithin the same dialect, and roosts in foreign dialect areas. Overall, pairs responded more strongly to duets from their own dialect than to those of t he foreign dialect. Pairs responded to both treatments from their own diale ct (local same dialect and distant same dialect) with movement towards the broadcasting loudspeaker and more rarely with squeals, a vocalization typic ally observed only in the context of aggressive chases. These aggressive re sponses were never observed during playbacks of the foreign dialect treatme nt or congeneric controls. There were no differences among treatments in th e incidence of contact calls or pair duets. A similar pattern of stronger a ggressive responses to local than to foreign dialects has been found in a w ide range of oscine songbirds. The results of the present experiment sugges t that a general function may underlie this behavioral response both in osc ines and in other bird taxa with vocal learning. Corresponding author: Timothy F. Wright, Department of Biology, University of Maryland, College Park, MD 20742-4415, USA. E-mail: tw98@umail.umd. edu.