The diet of grand skinks (Oligosoma grande) and Otago skinks (O. otagense) in Otago seral tussock grasslands

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 Leucopogonfraseri, 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.