Kangaroo Exclusion Treatment
Kangaroo densities in Mulligans Flat and Goorooyarroo are very high by national standards. Density estimates of 1.42 animals per hectare were made in Mulligans Flat in August/September 2008 and 1.95 animals per hectare in Goorooyarroo from October 2007 to January 2008 (Howland 2008; Howland, unpublished data).
High levels of kangaroo grazing pressure have had a visible effect on the ground layer in both reserves. The effects of kangaroo grazing on woodland ecosystems and biodiversity is of particular importance to the management of kangaroo numbers in the nature reserves of the ACT. There is very little literature on the effects of high kangaroo grazing on woodland ecosystems and woodland biodiversity. However, it can reasonably be assumed that grazing reduces biomass (affecting food and shelter availability for fauna), and alters moisture retention, nutrient cycling, plant community structure and composition.
To examine the effects of kangaroo grazing, exclosures have been established around half (48) of the sites (see figure below) to significantly reduce the number of kangaroos. Complete exclusion of grazing can be detrimental to vegetation communities that have evolved with grazing, therefore, the purpose of the fences was not to fully exclude kangaroos, but rather to significantly reduce relative numbers and effects. Kangaroos were herded out of exclosures. After herding, some kangaroos remained inside the exclosures, and some returned after being herded. When numbers of kangaroo increased inside the kangaroo exclusion area above 0.5 kangaroo per hectare – which was deemed the point at which they would have a significant effect - kangaroos were herded out again. Kangaroo numbers are monitored with direct counts and pellet counts.
Publications
- Barton, P.S, Weaver H.J. and Manning A.D. (2013) Contrasting diversity dynamics of phoretic mites and beetles associated with vertebrate carrion. Experimental and Applied Acarology 1-13.
