Response of Lumholtz’ tree-kangaroos (Dendrolagus lumholtzi) to odours from native arboreal and introduced terrestrial predators: A preliminary study

Background/Question/Methods

A significant threat to the endangered Lumholtz’ tree-kangaroo (Dendrolagus lumholtzi) in Far North Queensland (FNQ), Australia, is often-fatal attacks from domestic dogs (Canis lupus).  Dogs were brought to Australia with the European colonization of the country and thus are often found in agricultural landscapes adjacent to the remaining tropical rainforest fragments that tree-kangaroos inhabit.  It is possible that tree-kangaroos do not respond to dogs in the same manner as they respond to native predators such as the amethystine python (Morelia amethistina); this could explain the high number of tree-kangaroo fatalities (approximately 30 per year on the Atherton Tablelands of FNQ) as a result of dog attacks.  When threatened by a predator, tree-kangaroos descend from the canopy and flee on the ground.  This method of predator evasion works well for escaping arboreal predators, such as pythons, but is less efficient as an escape strategy against dogs, which pursue tree-kangaroos on the ground and  are more adept at terrestrial locomotion than tree-kangaroos.

This preliminary study reports the behaviours of two captive female tree-kangaroos towards odour cues from the native arboreal predator, a python, and the introduced, terrestrial dog.  The animals were observed in control trials, during which no odour sources were placed inside their enclosures, and in exposure trials, in which odour sources (urine, feces, shed skin) were placed within the animals’ enclosures.  An ethogram was created using this data, and the frequency and duration of comfort, locomotor, chemosensory, and discomfort behaviours were recorded in control and exposure trials.  The resultant comparisons were made in order to see whether and how the tree-kangaroos respond to different predatory odours.   

 Results/Conclusions

When exposed to either predator odour, the observed tree-kangaroos reduced the duration of their movements along tree branches as well as various comfort behaviours; additionally, the duration of sniffing behaviours increased. The results indicate that Lumholtz’ tree-kangaroos are able to detect and perceive predator odours.  The decrease in locomotion and the increase in sniffing behaviours could be indicative of increased vigilance, novelty shyness, or a generalized avoidance of these odours.    However, the subjects did not exhibit differences in their responses to dog and python odours.  Variations in the responses of the two subjects suggest that past predator experience may play a role in the behaviour of this species. These preliminary results will be explored further in future experiments.