New Zealand Journal of Zoology abstracts
The diet of grand skinks (Oligosoma grande) and Otago skinks (O.
otagense) in Otago seral tussock grasslands
Mandy D. Tocher
Science and Research Unit
Science, Technology and Information Services
Department of Conservation
Private Bag 1930
Dunedin
Abstract The threatened grand skink (Oligosoma grande)
and Otago skink (O. otagense) live sympatrically in seral tussock
grassland habitat of Otago, New Zealand. The diets of juvenile, male, and
female grand and Otago skinks were investigated at five sites (grand skinks)
and two sites (Otago skinks) in the vicinity of Macraes Flat, Otago. No differences
were found in the diet of Otago skinks in relation to site, age, and sex
class. For grand skinks, there was some evidence that site influenced diet,
but the data were not convincing. No sex or age-based diets were found in
grand skinks. In general, grand skinks consumed large quantities of small-bodied
dipterans, as well as substantial amounts of the fruit Leucopogon fraseri
and Melicytus alpinus. In contrast, Otago skinks consumed large amounts
of the fruit Coprosma taylorae and Leucopogon fraseri, small-bodied
coleopterans, and large bodied dipterans (Calliphoridae). Diet overlap between
grand skinks and Otago skinks was greatest in midsummer, and at this time
78% of food items detected were ingested by both species. Pronounced diet
separation was evident only in late summer, when both species ate only a
small range of food items, and some “specialisation” in fruit dietary items
was evident. Although both species appear to consume substantial amounts
of fruit, Otago skinks rely on fruit for most of summer. For grand skinks
fruit is also important, especially in May. Neither species are likely to
survive long-term any habitat modification that destroys fruiting plants.
Habitat restoration initiatives should target plant species favoured by both
species, in particular C. taylorae, L. fraseri, and Melicytus
alpinus.
Keywords diet; habitat; grand skink; Otago skink; Oligosoma;
frugivory
Z01027 Received 18 July 2001; accepted 17 March 2002; Online publication
date 8 September 2003
New Zealand Journal of Zoology, 2003, Vol. 30: 243-257
0301-4223/03/3003-0243 $7.00/0 © The Royal Society of New Zealand
2003
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