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Yourka detective work

Published 29 Jan 2019 by Terry Mahney (Ecologist)

It looks like a small kangaroo... but does it have rounded ears about the same height as the crown of its head, or does it have pointy ears that stand well above the head? Does it have a shaggy or smooth coat? Is the tip of its tail black?

It's a small, mouse-like mammal but does it have a sharp pointy nose and ears that extend down the side of its head, or does it have a normal house-mouse-shaped nose?

Adding to the challenge is that these photos are low resolution and from odd angles.

These were just some of the challenging questions when trying to identify animals from the 150,000 photos taken during a highly successful camera trap survey of the 2017-18 wet season at Yourka Reserve.

In partnership with the WWF (World Wide Fund for Nature), Bush Heritage set up 40 camera traps on the reserve for 50 nights to survey for the endangered Northern Bettong and to assess the status of other mammal species on the reserve. A total of 33 species were recorded on camera including:

  • 16 mammals (3 introduced),
  • 3 reptiles, and
  • 13 birds.

The results showed that the Rufous Bettong and Common Brushtail Possum populations at Yourka appear to be very healthy – they were recorded at 17 of the sites, the most for any of the species recorded.

Bandicoots were also recorded at six sites. This is good news as many of these medium-size native mammals have declined or become extinct in many areas of Australia.

Common Brushtail Possums are abundant and populations appear secure in southern Australia, however they're endangered in central Australia and their status is uncertain in northern Australia where they appear to have suffered declines, especially in the savannah woodlands.

A number of other small mammal species were also captured on camera but proved very difficult to identify. Excitingly some of them appear to be small dasyurids (carnivorous mouse-like marsupials) including Antechinus, Dunnart and Planigale. Others appear to be native rats (distinguished from introduced black rats by their tail being less than or equal to their head-body length. We also recorded three kangaroo species.

Unfortunately, two other species we hoped to find aren’t faring as well. No Northern Bettongs or Northern Quolls were recorded.

Both have suffered significant declines across their range. Northern Bettongs were once widespread along a 1,000 km stretch from Rockhampton through to far north Queensland. Now research by the WWF shows that they're known from just two small populations covering a total of just 145km².

Their decline is thought to be the result of predation by feral cats, changing fire regimes and habitat disturbance by cattle and pigs. The major cause for the Northern Quoll’s decline was the arrival of Cane Toads. However, in recent times Northern Quolls have recovered and re-established in some areas, having learnt to avoid eating the poisonous toads.

Bush Heritage Australia is doing much to ensure Yourka Reserve remains a healthy environment for those mammals that live there and to ensure it provides suitable conditions for the re-establishment and re-introduction of the species that have been lost. Managing stray cattle incursions is an ongoing challenge but fencing and seasonal musters keep their numbers and impact to a minimum.

Fire management and strategic wet season burns focused on re-introducing mosaic fire patterns are being used to reduce woody thickening and to encourage plants such as Cockatoo Grass (Alloteropsis semialata) which is favoured by the bettongs.

There's also an increased focus on the training and use of scent detection dogs in the control of feral predators.

The management team at Yourka have also been very successful in controlling weeds that would choke out habitat for native animals, including a particularly successful Siam Weed control program.

It's hoped that with all this good, ongoing management we'll continue to see healthy populations of Rufous Bettongs, Common Brushtail Possums and Bandicoots and the return of Northern Bettong and Northern Quolls. In the meantime we'll continue the hard work of maintaining and improving the ecological health of the property and monitoring its important wildlife populations.

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