Lizard Research at Windy Hill
by Judy Gilbert

 

There have been around 14 species of lizards identified on Barrier. Skinks and geckos are present in many places on the island but little is know about how well they are surviving with our high numbers of rats and feral cats. Like lizards all over the world they are difficult to monitor, being shy and often well camouflaged creatures.

In January 2007 Trent Bell from Landcare Research established 300 foam artificial covers onto trees at Windy Hill and Benthorn Farm within the Windy Hill Rosalie Bay Catchment Trust sanctuary area where rats and feral cats are managed to low densities. The objective of the project is to establish a method that allows for more effective monitoring of lizard presence and densities, particularly were numbers of animals are known to be at low levels. The current methods of trapping and night spotting are time consuming and the results often inconclusive.

Windy Hill is part of a three site research project taking place here on Great Barrier, on pest-free Fanal Is. in the Mokohinaus, and at Karori Sanctuary in Wellington. The trial has so far found that certain types of gecko will use the covers, Pacific geckos at Windy Hill and Forest geckos at Karori. As would be expected at Fanal Island where lizard numbers are very high, a range of lizards use the covers including the rare Duvaucels.

At Windy Hill and Benthorn Farm Trent found that small numbers of pacific gecko (9 in 2008,18 in 2009) and some sub-adults were present which indicated successful breeding. Covers are currently set out in transects (long lines) and later this year Trent hopes to establish clusters of the covers around the place on the transects where geckos were found. This way he hopes to get a better idea of the numbers of geckos present. Most lizards breed very slowly and more so when the numbers of breeding adults are much reduced through long term predation.

Landcare Research has been granted funding to continue and expand this research as part of a Government initiative to increase the populations of iconic species, such as lizards, by 25%. The Windy Hill Rosalie Bay Catchment Trust also monitors lizards using layers of Onduline to form lizard ‘motels’ and has found that Ornate lizards use these exclusively to other lizard species.

The benefit to the Trust and the island of the Landcare Research is the increased knowledge gained about the lizard populations here, the opportunity to work with an expert in his field, and the opportunity to contribute to science that may be applicable both in NZ and worldwide. A full report will be published in 2013.