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RESEARCH ARTICLE
Contents Vol 35(1)

VIEWPOINT. An hypothesis to explain the linkage between kakapo (Strigops habroptilus) breeding and the mast fruiting of their food trees

Andrew E. Fidler A D , Stephen B. Lawrence B and Kenneth P. McNatty C
+ Author Affiliations
- Author Affiliations

A Cawthron Institute, Private Bag 2, Nelson, New Zealand.

B AgResearch Wallaceville Animal Research Centre, PO Box 40-063, Upper Hutt, New Zealand.

C School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand.

D Corresponding author. Email: andrew.fidler@cawthron.org.nz

Wildlife Research 35(1) 1-7 https://doi.org/10.1071/WR07148
Submitted: 19 September 2007  Accepted: 24 January 2008   Published: 17 March 2008

Abstract

An important goal in the intensive conservation management of New Zealand’s critically endangered nocturnal parrot, kakapo (Strigops habroptilus), is to increase the frequency of breeding attempts. Kakapo breeding does not occur annually but rather correlates with 3–5-year cycles in ‘mast’ seeding/fruiting of kakapo food plants, most notably podocarps such as rimu (Dacrydium cupressinum). Here we advance a hypothetical mechanism for the linking of kakapo breeding with such ‘mast’ seeding/fruiting. The essence of the hypothesis is that exposure to low levels of dietary phytochemicals may, in combination with hepatic gene ‘memory’, sensitise egg yolk protein genes, expressed in female kakapo livers, to oestrogens derived from developing ovarian follicles. Only in those years when the egg yolk protein genes have been sufficiently ‘pre-sensitised’ by dietary chemicals do kakapo ovarian follicles develop to ovulation and egg-laying occurs. While speculative, this hypothesis is both physiologically and evolutionarily plausible and suggests both future research directions and relatively simple interventions that may afford conservation workers some influence over kakapo breeding frequency.


Acknowledgements

We thank Ron Moorhouse, Daryl Eason, Graeme Elliot, Don Merton and Murray Williams for their thoughts and helpful conversations. We are very grateful to Barbara Helm, John Sumpter and Peter Sharp for their helpful comments on an earlier draft of this manuscript.


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