Improving search strategies for the cryptic New Zealand striped skink (Oligosoma striatum) through behavioural contrasts with the brown skink (Oligosoma zelandicum).

The striped skink (Oligosoma striatum) is a poorly known New Zealand endemic species rarely seen in the wild despite ongoing efforts to locate specimens. It is uncertain whether its threatened status is due to low numbers, or to unusual habitat use and activity patterns that make it difficult to detect. Anecdotal reports indicate the species may be partly arboreal. We carried out captive-based behavioural comparisons between striped skinks and the common terrestrial brown skink (Oligosoma zelandicum). Brown skinks are of similar mass to striped skinks and overlap in geographic range and habitat, but are easily captured by hand and pitfall trapping in the wild. They were therefore a suitable comparison from which to assess activity levels and arboreal tendencies in striped skinks, with the aim of improving survey methods. Point samples and total frequencies of behaviours were collected using time-lapse video recordings taken concurrently of individuals of each species occupying identical enclosures. Striped skinks had significantly higher levels of diurnal activity than brown skinks. They also showed periods of nocturnal activity associated with high moisture levels. When active, the types of behaviours carried out by each species were very similar, as were the proportions of active time spent carrying out each behaviour. Striped skinks spent significantly longer periods at greater heights within the enclosure than brown skinks, indicating stronger arboreal tendencies. High levels of arboreal activity and in particular nocturnal activity may make striped skinks more vulnerable to introduced predators such as rodents and possums. In order to accurately assess the status and carry out long-term monitoring of the striped skink, new survey and capture techniques will be required. Arboreal traps, visual canopy surveys and surveying felled trees are recommended.