New Zealand Journal of Zoology abstracts
Induction of oviposition produces smaller eggs in tuatara (Sphenodon punctatus)
Nicola J. Nelson1
Michael B. Thompson2
Shirley Pledger3
Susan N. Keall1
Charles H. Daugherty1
1School of Biological Sciences
Victoria University of Wellington
P.O. Box 600
Wellington, New Zealand
email: nicola.nelson@vuw.ac.nz
2School of Biological Sciences and Wildlife Research Institute
Heydon-Laurence Building (A08)
University of Sydney
NSW 2006, Australia
3School of Maths and Computing Science
Victoria University of Wellington
P.O. Box 600
Wellington, New Zealand
Abstract Induction of oviposition by injection of hormones has been used successfully to collect eggs from at least three orders of reptiles. Eggs of tuatara (Sphenodon spp.) have been collected by induction since 1985. We investigate whether inducing egg laying affects clutch size, egg mass, hatching success, or hatchling size, and describe considerations necessary when deciding whether to induce egg laying or collect eggs from nests. Altogether, 320 tuatara (S. punctatus) eggs were collected for incubation from Stephens Island in November 1998: 166 by induction and 154 from nests. Induced eggs (mean = 4.498 g ± 0.060 SE) were significantly smaller than naturally laid eggs collected within a few days of oviposition (mean = 5.375 g ± 0.070 SE). Induced eggs resulted in significantly smaller hatchlings following incubation in captivity, and the difference was still significant when hatchlings were 10 months old. Reduced size of hatchlings has consequences for long-term fitness.
Keywords Sphenodon; tuatara; oviposition; induction; egg size; incubation
Z04008; Received 9 March 2004; accepted 12 July 2004; Online publication date 24 November 2004
New Zealand Journal of Zoology, 2004, Vol. 31: 283–289
0301–4223/04/3104–0283 © The Royal Society of New Zealand 2004
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