Survival,density and population composition of bellbirds (Anthornis melanura) on the Poor Knights Islands,New Zealand |
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Authors: | P. M. Sagar R. P. Scofield |
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Affiliation: | 1. National Institute of Water and Atmospheric Research , PO Box 8602, Riccarton, Christchurch, 8440, New Zealand E-mail: p.sagar@niwa.co.nz;2. Canterbury Museum , Rolleston Avenue, Christchurch, 8013, New Zealand |
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Abstract: | Abstract Annual survival by age, sex and population size and structure were estimated for bellbirds (Anthornis melanura) from a banding study undertaken on 66 ha Aorangi Island, the Poor Knights Islands, during the period 1978–86. The most parsimonious model showed that survival varied little with age and between years, and survival of males was significantly greater than that of females. Recapture probabilities of males and females were similar, but did vary with age and among years. There was a greater proportion of adult males than adult females and sub‐adult males and females in the population, and among adults the male bias in the population was greater during the breeding season than at other times of the year. The high density of bellbirds on the Poor Knights and larger size of males may explain the reduced survival of females relative to that of males. |
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Keywords: | Meliphagidae program MARK survival population size estimation reproductive success sex ratio male‐dominated hierarchy |
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