Social organisation of the Nicobar megapode Megapodius nicobariensis (Galliformes) in the Great Nicobar Island

Abstract

The Nicobar megapode Megapodius nicobariensis is a mound nesting bird, endemic to Nicobar Islands. Colour-marked megapode reveals that it is primarily a monogamous species, although temporary pair bonds, change in partner and extra-pair copulation are also observed in this species. During our study, unpaired megapodes tried to steal the mate from an existing pair and it lead to changes in partnerships, extra-pair copulation and temporary pair bonding. An egg-laying pair showed dominance over a non-egg-laying pair. However, the dominant rank in the society of the Nicobar megapode was not consistent, and it varied temporally and spatially. Dominancy status appears because of the mound rather than the territory although they are territorial throughout the year. Alpha pairs were more likely to show mound and territory fidelity than beta pairs. Territories overlapped where a large number of pairs used a mound. The average size of the territory was 0.81 ± 0.12 ha. A major function of the territory of the Nicobar megapode was to protect the mound from neighbours or strangers. Both partners of a pair equally defended their territory from others. In this chapter, the reasons for monogamous mating system in the Nicobar megapode were discussed and also attempted to explain the reasons for extra-pair copulation.