Outback Inquests

PhD students are using an outback Queensland National Park to revive one of Australia's rarest wallabies, learn more about echnidas and discover new insects.

UQ researchers have been making annual field trips to Idalia National Park, a 144,000-hectare-property southwest of Blackall, for 13 years. Idalia is home to a wide range of rare and endangered animals which live in its mulga and brigalow scrub.

It is the base for a breeding and research program of one of Australia's rarest native animals ? the bridled nailtail wallaby.

UQ research has shown the wallaby leads a solitary life until mating, when males will stalk females for up to a week digging their hard-tipped tail, similar to a nail, along the ground to "woo" partners.

"I saw one group do it once . . . and there was this thin clear line in the ground for about 20 metres," UQ ecologist and nailtail expert Dominique Sigg said.

"My interpretation of it is that the males compete for access to the females but they do not actually fight with each other directly like other macropods."

Ms Sigg, who is finishing her PhD on the genetics and mating behaviours of the nailtail, said the wallabies were loners compared to their red and grey cousins and lived in structured populations that bred rapidly but did not move far.

Several generations of captive-bred wallabies from Taunton National Park, west of Rockhampton, have been released at Idalia since the first batch was transferred in 1996.

She said the Idalia wallabies were yet to recover from the 2002 drought, and the genetic diversity, which indicated a healthy population, was high at Taunton but had decreased at Idalia.

The wallabies were once common from Charters Towers to the Murray River but now only a single wild colony remains at the Taunton National Park.

Good rain is the key to a nailtail recovery at Idalia and Ms Sigg will return to the national park later in the year to check if numbers have bounced back.

In addition to wallabies, it appears Idalia has a booming echidna population. Four echidnas were collected on the last Idalia field trip in July as part of research into how the animals raise their body temperature at the end of hibernation and how they cope in hot climates.

Echidnas can vary their body temperatures between three and 35 degrees Celsius and PhD student Dave Ellis wants to find out how they do it internally.

His theory is that echidnas use a calcium pump system through the skeletal muscles or a hormone similar to adrenalin to heat up.

Fellow PhD student, Peter Brice, is investigating how echidnas survive summer temperatures of more than 40 degrees Celsius when lab tests have shown a rise in their body temperature to 38 degrees can be fatal.

Echidnas can't sweat or pant but Mr Brice believes they survive the heat by slowing their metabolic rate, varying their blood supplies and using insulation of their spines, hair and fat layers.

Both researchers are studying echidnas, taken under permit from Idalia, at UQ's Pinjarra Hills facility.

Idalia is also a haven for insects with five potentially new species of cicadas discovered. A dried specimen from the genus Tryella and several Cicadettini shells were found on the July trip.

Cicadas are sap-sucking bugs that use their probosci to feed and are known for their droning sounds. Cicada expert and PhD student Lindsay Popple said classification would take a long time because he would have to check museum records and needed more of the species to record their songs.

"It's not unusual to find new species, especially in places like this where it's fairly desolate and isolated," Mr Popple said.

"Only a few years ago, one of the biggest cicadas was described and found in this area."

Mr Popple is researching cicada acoustics and has spent much of his time recording and analysing cicada songs to pinpoint elements important for mate recognition.

Only the males sing songs, which vary in length from less than a second to more than half an hour depending on the type, and each species has its own distinct mating calls.

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