The Herpetological Journal

pp. 237-241
Authors: Jones, Christopher & Bell, Trent

Abstract: There has been much debate about the use and acceptability of toe-clipping as a means of permanently marking reptiles and amphibians during scientific surveys. Trapping studies of reptiles and amphibians are frequently, although not always, compromised by low probabilities of recapture of individuals following their initial capture and marking. Low recapture rates can influence the precision of estimates of population size and home range that are derived from trapping data. We investigated whether there was a difference in the short-term probability of recapture of toe-clipped McCann's skinks (Oligosoma maccanni) compared with those marked non-invasively with a pen. We pitfall-trapped skinks for seven days in a dry scrub habitat on the South Island of New Zealand. On first capture, skinks were individually marked by either toe-clipping or writing a code on their ventral surface with a silver marker pen. The resulting recapture histories for 118 skinks were analysed using Huggins' closed-population models in the MARK program. The best supported models indicated that recapture probability was significantly affected by sex (females > males) and previous toe-clipping experience (previously clipped > not). There was no support for an effect of marking method on short-term recapture probability, which is likely to be affected by other sampling factors such as trap spacing, social behaviour or response to handling. Females' higher recapture probability may reflect their increased energetic requirements during the breeding season, making them more likely to enter traps in search of food. We speculate that previous experience of toe-clipping is a surrogate for age and social dominance leading to increased access to traps.

Keywords: MARK-RECAPTURE, MARKING METHODS, OLIGOSOMA SPP