Fighting over the scraps: Predator interactions and the ecosystem effects of carrion

A project undertaken at the Centre for Integrative Ecology, Deakin University, and supervised by Thomas Newsome and Euan Ritchie

Carrion (i.e. dead or decaying animal matter) is a nutrient- and energy-rich resource that is used by a variety of organisms encompassing all biological kingdoms. It can affect the movements and spatial distribution of scavenging species and, as many scavengers are also predators, the presence of carrion may have cascading impacts on live prey. The degradation of a carcass may further influence soil properties, as well as the growth of certain plant species in the vicinity of the resource. Thus, carrion has the potential to shape many aspects of community ecology, and to play key roles in nutrient cycling and in shaping food-web dynamics through both direct and indirect pathways.
Despite the community-wide effects of this resource, carrion ecology remains understudied, and research is primarily northern-hemisphere based. This represents a major knowledge gap and issue for Australia, especially given the suite of predators (e.g. dingo, red fox, cat, quoll, eagle, goanna) that potentially use this food source. Better understanding of how these predators use the landscape and their resources will ultimately help to determine and refine appropriate conservation, wildlife and pest management strategies. Further, little is known in Australia about the extent to which detritivores (organisms that feed on decomposing organic matter) use carrion, and similarly, whether there are flow-on effects to soil properties. Our project addresses these gaps, as it investigates how carrion shapes ecological communities in Australia.

Specifically, our project aims to:

  1. Determine the extent to which different predator guilds use carrion resources within the landscape;
  2. Examine the interactions that occur between different predator species at carrion sites;
  3. Examine the factors that influence the use of carrion by different predators; and
  4. Assess the extent to which detritivores use carrion and whether there are any flow-on effects to soil properties (soil fertility and chemistry).

The results of this research will provide capacity for and inform broader and more complex ecological studies into the role of carrion in Australian food-webs and contribute to carrion management (i.e. disposal programs) in the conservation and agricultural sectors of Australia. 

 

Figure 1. The Wolgan Valley study site, set on the north-western end of the Blue Mountains National Park. Photo credit: Thomas Newsome

Figure 2. Preparing a site for carcass placement. Photo credit: Thomas Newsome

Figure 3. Setting up remote sensor cameras to document scavenging activity at carcass sites. Photo credit: Thomas Newsome

Figure 4. Two wedge-tailed eagles (Aquila audax) fight over the remains of an eastern grey kangaroo. Picture taken using a Reconyx motion sensor camera.

Figure 5. A lace goanna (Varanus varius) moves in to feed on the remains of an eastern grey kangaroo. Picture taken using a Reconyx motion sensor camera.

Figure 6. A cheeky raven (Corvus coronoides) pulls at the tail feathers of an unsuspecting wedge-tailed eagle (Aquila audax). Picture taken using a Reconyx motion sensor camera.

Figure 7. Two wild dogs feed at the remains of an eastern grey kangaroo. Picture taken using a Reconyx motion sensor camera.