Long incubation bouts and biparental incubation in the nomadic Banded Stilt

Abstract

Parental care strategies have been widely investigated in shorebirds that undertake long-distance regular migrations. In contrast, virtually nothing is known of the parental care of nomadic, opportunistically breeding shorebirds, although the irregular and short-lived nature of their breeding potentially accentuates the trade-offs between investment in successive clutches and between the sexes. We investigated the incubation behaviour of the nomadic, opportunistically breeding Banded Stilt (Cladorhynchus leucocephalus). Seven nests, filmed continuously with day—night cameras over 2–7 days, revealed that both sexes contributed to incubation, with males apparently the sole carer during hatching and early brood-rearing; this is a possible adaptation, which enables females to quickly produce a second clutch if favourable conditions persist. All incubator changeovers occurred after dark; incubation shifts averaged 44.8 ± 10.9 (s.e.m.) h (n = 11, 17.5-139.6 h), the longest recorded for any shorebird. Incubation constancy averaged 96.5%; this high value is possibly an adaptation to high predation and the need for rapid embryonic development in the face of ephemeral resources for breeding. Long incubation shifts may be explained by extended foraging trips to distant areas of the partially inundated salt-lake surface, where food resources had been concentrated by wind-driven water movement.