Do black-flanked rock-wallabies compete with kangaroos?

By Julia White. Paruna Sanctuary is privately managed by the Australian Wildlife Conservancy (AWC) as a wildlife corridor between Avon Valley National Park and Walyunga National Park near Gidgegannup. It’s partial predator-proof fencing means that it serves as a refuge for some very special fauna, including the endangered black-flanked rock-wallaby.

These little wallabies are reasonably selective in what they eat. About half of the plant material was identified as forbs. Pincushions (Borya sphaerocephala) were the most common plant species eaten, followed by bellardia (Bellardia trixago; an introduced weed species). Rock-wallabies showed a preference for these plants – eating them disproportionately to their abundance.

Other important food plants were grasses (the most common grass being annual veldtgrass (Ehrharta longiflora, another weed), ferns, and browse.

Their selective diet raised the question of whether rock-wallabies face competition for food from western grey kangaroos, which are quite numerous in the park. To address whether the kangaroos feed in the same areas as rock-wallabies, I put out camera traps to monitor the activity of both species.

Rock-wallabies shelter in caves and crevices during the day, and so it is a rare sight to see one. The camera traps therefore provided a great opportunity to observe these wonderful critters.

Curious young rock-wallaby investigates a camera trap (top), and a rock-wallaby family unit (below)

While there was strong overlap in the diets of rock-wallabies and kangaroos (56% of their food plants were common to both species), the was less overlap in where they choose to forage, with only 33.9% of camera traps recording both species. Kangaroos tended to be more active upslope or downslope, but less active on the steep hillsides where they rock-wallabies live and forage.

Unfortunately, while they face some competition from kangaroos, photos also confirm that feral cats are a key threat to wildlife species around the rock shelters used by rock-wallabies.

Feral cat that preyed on a gonna

This study has been published and is available here PDF

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