Issue 7
Monday, 02 September 2019
Charles Darwin University
PhD candidate Cara Penton’s research tracking small mammals on the Tiwi Islands has taken her to great heights
PhD candidate Cara Penton’s research tracking small mammals on the Tiwi Islands has taken her to great heights

Finding the rat in the haystack

By Jon Taylor

PhD candidate Cara Penton has gone to great lengths to track small mammals on the Tiwi Islands.

Cara is investigating how the brush-tailed rabbit-rat, black-footed tree-rat and common brushtail possum rely on hollow logs and tree hollows.

This entailed fitting radio trackers to 41 animals belonging to the three target species

“From there it’s a matter of walking around the bush, holding what looks a bit like a TV antenna over your head, listening for a beep. The trackers are supposed to have a range of one kilometre but it’s more like 600 metres in the field,” she said.

“I think I’ve walked at least 200 kilometres tracking those animals. Once I spent three hours walking around before hearing anything at all. The beeps get louder as you get closer and I can identify which trees or logs the target animal is nesting in.

“It can feel like a needle in a haystack. I’m looking for a small animal that is using one tree out of 1000,” Cara said.

Snakes are a constant hazard.

“Walking around holding an antenna in the air and looking for tree hollows you don’t tend to spend time looking at your feet, so there were a few near misses with king browns,” she said.

After more than 230 days in the field over three years, Cara has been able to identify that all three species relied on tree hollows for shelter, with larger tree hollows preferred.

“We also found that these mammals didn’t travel far and tended to use a lot of tree hollows or hollow logs within a one hectare area.”

Cara said fire may be impacting the ability of small mammals across North Australia to find protection.

“Until recently we saw lots of late Dry Season fires. These generate lots of heat and are capable of destroying trees and the tree hollows used as mammal habitats,” she said.

“Now, with the induction of the carbon credits, there is an incentive to reduce fires, which means we may see earlier Dry Season burning. The next phase of my research will look at whether this better preserves the tree hollows and hollow logs relied upon by small mammals for shelter.”

Cara’s project is funded by the Australian Research Council, the Department of Biodiversity, Conservation and Attractions of Western Australia and supported by the Traditional Owners of Tiwi Islands, Tiwi Land Council and Tiwi Plantations Corporation.