Nesting success and breeding ecology in a high-density population of Brown Kiwi (Apteryx mantelli)

Abstract

Brown Kiwi (Apteryx mantelli) are in serious decline despite immense conservation efforts. The lack of fundamental information on Kiwi breeding is in part because of the low density of most populations and their nocturnal habits. We report on the nesting success and breeding ecology of an exceptionally high-density population of Brown Kiwi over 3 years. Nesting success was high (47%) compared with other Brown Kiwi populations and 85% of failures occurred during incubation. In contrast, fledging success was very high (89%). Most clutches had one egg (69%), and second and replacement clutches were rare. Significantly more chicks hatched in reused nests than previously unused burrows. In addition, two nest usurpations and one cooperative nest were observed. We suggest that competition for resources associated with high densities result in reduced clutch-size, nest reuse and nest usurpation and that such life-history traits are particularly relevant for species such as Brown Kiwi with high energetic demands for breeding. Given that the density of Kiwi on Ponui Island is indicative of pre-human New Zealand, this study provides insights into the breeding ecology of Brown Kiwi not otherwise possible. Indeed, our study reveals certain previously unknown aspects of Brown Kiwi life-history indicating ecological resilience.

Additional keywords:

• clutch-size
• conservation
• island
• nest-site fidelity
• population decline
• ratite
• reproduction
• threatened