Sunday, July 10, 2011

Lizards

I saw a skink recently amongst the rocks in the Waiau riverbed. It saw me first so I got no more than a quick flash – a hint of brown and yellow and it was gone. No point looking for it as skinks can worm their way down through rocks or tussocks and secrete themselves in the narrowest crevices. This is the reason we still have lizards. A tiny, tasty scrap of meat, unable to fly or swim or climb trees would be a picnic for a stoat or rat.

There are at least four skinks around. Recent discoveries in Fiordland suggest that there may be tiny isolated populations of new species of gecko and skink still to be found. Let’s hope so.

Common Skink

The four we have are the Common skink, Cryptic skink, McCann’s skink and the Emerald skink. The first three are the common little brown lizards, about 12cm long, that we encounter sometimes in abundance in a suitable dry habitat. They eat small insects, spiders and berries. The Emerald skink gets to about 20cm. It is much less common and best known from the Tiwai Peninsula. Here its main predators are wild cats. It is quite a stocky creature and slower and more vulnerable.

Pre-human and thus pre-rat, Southland was a very different place. A few fossil bones preserved in sediment and cave deposits give some idea of the many species that went extinct with the arrival of the kiore or Polynesian rat. Southland may have had dozens of lizards in all manner of niches and today’s populations are the species that have survived, albeit in very reduced numbers, because they were small and fast and lived in habitats that offered a quick escape. Tree-dwelling lizards and those that lived on the forest floor are gone. We had the tuatara in Southland. Bones are found in dune deposits along the coast and in Central Otago and a mummified specimen was found in a cave.

These lugubrious survivors of the dinosaur age were no match for rats and they exist today only on predator-free islands. I wonder of we had snakes as well? There is no evidence of recent snakes but millions of years ago we almost certainly did. A pity we haven’t still got them. If we did we have snakes we would also have predator-proof birds and probably a lot more lizards as natural selection favoured those with the genes to run fast, dodge trouble spots, breed rapidly, modify behaviour or whatever was necessary for them to co-exist with their enemies.

Emerald Skink

I’ve got skinks in my garden and I’m building a lizardium with rocks and tussocks. They are protected so you can’t officially keep them without a permit but this is just habitat enhancement – they are free to come and go. I’m hunting for a square of thick perspex to cat-proof part of it. Much as I dislike cats I suspect that without them I would have rats and stoats and possibly no lizards at all.