Bilbies’ burrow building takes a hit from feral cats

By Faith Chen. The greater bilby (Macrotis lagotis) is an important ecosystem engineer. Their extensive burrows provide important shelter, foraging and hunting opportunities for a variety of other mammals, birds, reptiles, and invertebrates (Hofstede & Dziminski 2017; Dawson et al. 2019).

Bilbies were once widely distributed across the Australian continent but are now restricted to about 20% of its former distribution (Southgate 1990). Feral cats represent one of the greatest threats to bilbies. Predators can directly impact prey species’ survival and may also cause a change in the behaviour of prey species as they respond to the risk of predation.

Bilbies are likely to be more vulnerable to predators when they are doing their housework. With its head in the burrow (blocking vision and hearing) and making noise through digging that will mask any sounds of an approaching predator, as well as attracting a predator’s attention, bilbies are more likely to be caught unawares at this time.

We used camera traps to compare the bilbies’ behaviour at their burrows to identify whether the presence of feral cats influences whether bilbies move out of their burrows, or change their burrow maintenance behaviour.

Bilby digging in the West Kimberley.

There was little evidence that bilbies avoided burrows after a visit by a feral cat. This is not too surprising, as a burrow represents a significant energy investment to dig.

However, bilbies did reduce the proportion of time in front of the burrows that they spent performing burrow maintenance in the days following a cat visit. This result suggests that bilbies in the West Kimberley are not naïve to feral cat presence, and alter their behaviour accordingly.

Let burrow construction for public housing continue.

References

Dawson SJ, Broussard L, Adams PJ, Moseby KE, Waddington KI, Kobryn HT, Bateman PW, Fleming PA (2019) An outback oasis: the ecological importance of bilby burrows. Journal of Zoology308: 149-163. doi:10.1111/jzo.12663.

Hofstede L, Dziminski MA (2017) Greater bilby burrows: important structures for a range of species in an arid environment. Australian Mammalogy39: 227-237. doi:10.1071/am16032.

Southgate RI (1990) Distribution and abundance of the greater bilby Macrotis lagotis Reid (Marsupialia: Peramelidae), 293-302.

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