Item on the effect of supplementary feeding on Kakapo offspring sex rat

To: Birding Aus <>
Subject: Item on the effect of supplementary feeding on Kakapo offspring sex ratio
From: Laurie&Leanne Knight <>
Date: Wed, 22 May 2002 19:30:49 +1000
I came across the following item the other day and have attached the abstract 

Biological Conservation 

Volume 107, Issue 1 
September 2002 
Pages 13-18

DOI: 10.1016/S0006-3207(01)00267-1 
PII: S0006-3207(01)00267-1 
Copyright © 2002 Elsevier Science Ltd. All rights reserved. 

Effects of supplementary feeding on the offspring sex ratio of kakapo: a dilemma
for the conservation of a polygynous parrot 

Mick N. Clout, , a, Graeme P. Elliottb and Bruce C. Robertsonc 

a School of Biological Sciences, University of Auckland, PB 92019, Auckland, 
New Zealand
b Kakapo Management Group, Department of Conservation, Private Bag 5, Nelson,
New Zealand
c Zoology Department, University of Canterbury, PB 4800, Christchurch, New

Received 10 August 2001;  revised 18 November 2001;  accepted 23 November 2001. 
Available online 20 January 2002. 


The kakapo (Strigops habroptilus) is a large, flightless, nocturnal parrot,
endemic to New Zealand. It is critically endangered, with a world population of
ca. 62 individuals and a male-biased adult sex ratio. The species has a
polygynous "lek" mating system and adult males typically weigh 30¯40% more than
females. The kakapo is subject to intensive conservation efforts, including the
provision of supplementary food to wild birds to encourage successful nesting.
There is mounting evidence that, in polygynous species with large variance of
male reproductive success, females in better condition may maximise their
fitness by producing more offspring of the larger, more costly sex to be reared.
We used data on the sex ratio of progeny of female kakapo that had or had not
received supplementary food, to test the hypothesis that supplementary feeding
might cause a male-biased offspring sex ratio. There was a significant excess of
males in the clutches of females provided with supplementary food, suggesting
that changes need to be made to the feeding regime to increase recruitment of
females. This is an example of applying evolutionary theory to a practical
conservation problem.
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