Name that tune: call discrimination and individual recognition in Magellanic penguins

Individual recognition via vocalizations is key to reproductive success in many species. We explored individual recognition and call discrimination in Magellanic penguins, Spheniscus magellanicus, through several playback experiments. By using two call types in multiple social contexts, we demonstrate, for the first time in a Spheniscus species, that adults and chicks can discriminate between conspecific calls. We played male ecstatic display calls, including calls of a neighbour, stranger and mate, to incubating females and, later, played this same set of calls to their mates. Females responded more strongly to ecstatic display calls of mates versus neighbours; and strangers but did not discriminate between calls of neighbours and strangers. Males showed no difference in response to their own ecstatic display calls and those of neighbours and strangers. We also played mutual display calls of mated pairs and stranger pairs to both pair members during incubation and, later, to their unattended chicks. Reaction to mutual display calls for both sexes was similar, showing a significantly stronger response to their own mutual display call than to that of a stranger pair. Chicks responded more strongly to the mutual display call of their parents than to that of a stranger pair. Few playback experiments consider experimental and ecological factors that might affect playback results. We found several ecological factors that correlated strongly with response to strength: longer-mated females responded less strongly to their mate's call, males responded more strongly later in the season, and chicks responded less strongly at higher temperatures. (c) 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.