Saving the Skink

A

New Zealand's reptiles come in three forms: the tuatara, the geckos and the skinks. With their gleaming scales, long bodies and often surprisingly short limbs, skinks are instantly recognisable. There are more than 90 species, half of which still await formal description. Identification depends on where specimens are found, and such minutiae as the number of scales on their toes. Two of the largest species of skink – the grand and the Otago – are found only in Otago, in New Zealand's South Island. Skinks, being reptiles, need to regulate their temperature, and lie on sunny rocks to absorb heat. However, the grand and Otago are the only kinds that do not hibernate through winter; when snow can fall even in summer in Otago, there is no point in them lying dormant for extended periods. Like all other New Zealand reptiles except tuatara and the egg-laying Suter's skink, they give birth to tiny baby lizards. Today, the Otago and grand skinks are lucky to reach five years of age in the wild, although in zoos or research centres they can live beyond thirty.

B

Unfortunately, extinction may loom for these reptiles. With any decline in New Zealand fauna, predation is always suspected, so the efforts of the Department of Conservation (DOC) have focused on controlling specific pests. An example was a six-year project to control the feral cats on the Otago Skink Reserve, launched in the 1990s. Despite the capture of hundreds of cats, skinks showed no signs of recovery; indeed, there were further declines. The trapping programme also revealed rats and hedgehogs to be predators.

C

Parasite infections are also thought to be on the rise. Although no direct health implications have been detected, the trend is a concern, as it may signal a subtle deterioration in the skinks' living environment. Infection with mites is suspected of inhibiting reproduction among captive animals.

D

Another potential threat is habitat loss. Eight hundred years ago, Otago was covered in forest. However, extensive burning produced wide open tussock country. The skinks' response to this change isn't known, nor what their habitat was in the earlier environment, with its predominance of shrubs and trees. Furthermore, recent intensive farming has led to poor soil. Even if we had the answer to the eradication of predators, we haven't a clue to the habitat we should be recreating for the skinks, or if where they persist is best for conservation.

E

It is also puzzling that grands and Otagos are disappearing more rapidly than other species in the same region. The explanation likely lies in their delayed sexual maturity. Taking five years before you can breed is a handicap, since there is little likelihood of surviving that long. If survivors have only two offspring annually, they do little to remedy the situation. The commoner skinks mature earlier and produce more offspring, thereby doing more to counter predator pressure. Not that there is room for complacency concerning these species. As more is learned about the size of skink populations, it becomes clear that even common species may be facing a doubtful future.

F

So far, DOC's efforts to eliminate specific predators have not resulted in a recovery of skink numbers. The prediction that less than six years is all the Otagos and grands have left is supported by data from surveys conducted outside the protected area between 1984 and 2002. These show that more than 50 per cent of sub-populations of both skinks have died out over the past years. Populations in other regions are believed to be smaller, although access issues on some properties limit knowledge. No more than five years remain in which to turn things around – a close call considering it will be at least three before detectable response in the populations can be expected owing to their low breeding rate.

G

DOC's recovery programme team has recently embarked upon an experiment to extend nearly two kilometres of mammal-proof fencing around a population of Otagos and grands in the Macraes Flat reserve. Choosing a site was difficult, as with a limited budget and the high cost of the fencing it had to be small. It also had to include vacant space and resources for a growing population. An added complication was that grands and Otagos have subtly different environmental preferences, both of which need catering for.

H

Because of the danger of imminent extinction, the team has also had to develop emergency captive-management techniques. Specially permitted breeders, who have had some success in breeding the Otago in captivity, are now developing techniques to breed grands. Captive management, however, is a last resort. The priority is to manage and protect skinks in the wild.

I

Getting the public to understand the plight of these creatures is essential. Without public support, their chances are slim. Conservation is as much driven by public opinion as it is by political decisions. In New Zealand, the situation is more pressing than just about anywhere else on the planet because many of its native birds and lizards have simply not evolved to defend themselves against species introduced in the last few hundred years. In the once-isolated islands that form New Zealand, ecosystem collapse didn't happen 5000 years ago or even 500 years ago; it's happening now.

J

Fortunately, DOC no longer faces these problems alone. The challenge has been taken up by a group of conservationists representing business, science and agriculture. Central Otago Ecological Trust (COET) aims to establish a refuge for the reintroduction of native species. It has identified suitable habitat and, with the generous support of a local farmer with grazing land there, has begun the construction of a mammal-proof fence to protect a 24-hectare area. The recovery programme and COET provide hope that skinks might once again flourish.