Fishing for Australia’s ‘laziest’ lizards
IN A PARCHED SHEEP paddock in South Australia, I once went fishing for lizards. Tying a mealworm to my fishing line, I then lowered it down one spider burrow after another and soon felt a bite. By pulling gently I brought into view something unique – an endangered pygmy bluetongue.
After going missing in the 1960s this lizard was thought to be extinct, until in 1992 one was found dead in the stomach of a brown snake. They are known today from a scatter of sheep paddocks in rolling hills north of Adelaide. When biologist Lucy Clive showed me where they live I saw why they were overlooked for so long. No one would expect a lost species to survive among the dried grass stalks and meagre weeds of dusty paddocks. The burrows aren’t obvious. The lizards are seldom seen even by experts unless they have fishing rods and know exactly where to go.
The pygmy bluetongue has to be much smaller than other bluetongues because it depends on trapdoor and wolf spiders to build it homes. You might think a lizard would be better than a spider at digging holes but these lizards don’t try. They don’t even widen the holes they acquire.
Pygmy bluetongue lizard (Tiliqua adelaidensis). (Image credit: Joyanne Gardner)
As lizards go they are probably Australia’s laziest. Cameras trained on their burrows for long stretches show they nab passing insects, but seldom leave their burrow entirely. If something tasty is more than a lizard-length from the hole, it usually goes uneaten. For most of each day they remain down their lair, head facing up, hoping something falls in. They sun themselves in the mornings, but usually leave their rear end in their hole. They drink by licking dew and fallen raindrops around the burrow mouth. They do vacate it entirely to go to the toilet, leaving their business an average 68.54cm away (scientists have been busy with tape measures). And because only one lizard can occupy a burrow, in spring the males go walkabout in search of mates.
Cameras trained on their burrows reveal why they seem lazy, by showing them retreating down their burrow as a brown snake approaches. The grasslands they inhabit are often so bare that only in their hole are they safe. But not entirely. Foxes sometimes dig them out and snakes try to pull them out. The supply of spider burrows doesn’t meet demand and any unattended hole is apt to be stolen by another lizard, providing another reason to not vacate it.
The relationship these lizards have with the spiders they rely on is not kindly. They eat spiders that are small enough, while large spiders have been known to poison them with a lethal bite.
This lizard faces a risk from climate change. Cropping has deleted it from the cooler part of its range near Adelaide. Plans exist to create new colonies further south. Lucy is doing research to see if moving the lizards could harm other reptiles.
The pygmy bluetongue has become one of our best-studied reptiles, because research is needed to save it, and because by staying put rather than roaming around it is convenient to study. Proximity to a capital city has helped as well, but even so the species remains mysterious. Much of what we know has come from rare actions captured by cameras, and cameras don’t reveal everything, including, for example, whether the lizards evict spiders or only claim vacated holes.
Animals afford us an opportunity to reflect on lives that are different from ours. I left that paddock wondering what life would be like in a dark hole waiting for meals to fall in. I wouldn’t want to be a pygmy bluetongue but I am glad they exist and hope they do well in future.