New Zealand Journal of Zoology abstracts
Survival, density and population composition of
bellbirds (Anthornis
melanura) on the Poor Knights Islands, New Zealand
P. M. Sagar
National Institute
of Water and Atmospheric
Research
PO Box 8602
Riccarton
Christchurch
8440, New Zealand
p.sagar@niwa.co.nz
R. P. Scofield
Canterbury
Museum
Rolleston Avenue
Christchurch
8013, New Zealand
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.
Keywords Meliphagidae; program
MARK;
survival;
population size estimation; reproductive success; sex ratio;
male-dominated
hierarchy
New Zealand
Journal of Zoology, 2006, Vol. 33: 249–257
0301–4223/06/3304–0249 © The Royal Society
of New Zealand
2006
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