Behavioural synchrony in two species of communally housed captive penguins

Animals in aggregations such as herds, schools, flocks, or colonies tend to synchronize their behaviour with each other for food acquisition and predator detection. Different species of captive penguins, when housed communally, intermingle more than in their natural habitat. Wild penguins typically divide themselves into separate colonies by species. We predicted that penguins would synchronize their behaviour more with conspecifics rather than interspecifically in a mixed-species zoo exhibit. The subjects were 65 penguins of two different species, chinstrap (Pygoscelis antarctica) and gentoo (Pygoscelis papua) in the Central Park Zoo, New York, NY, USA. Using instantaneous scan sampling, 359 video scans were taken over 10 days. Scans were analysed for nine different categories of behaviour for both species. Intra-species synchrony scores were calculated using the Kappa coefficient of agreement, and inter-species synchrony was measured by computing cross-correlations. As predicted, overall synchrony was significantly greater within both species of penguins than for randomly aggregated data representing mixed groups. There was also significantly less synchrony between species than between randomly mixed data for six of the nine behaviour categories. The pattern of results indicates that the penguins had organized by behaviour into separate species-specific colonies within the enclosure. They maintained species separation through behavioural synchrony despite the restrictions imposed by captivity.