Conservation Impacts of Grazing by Eastern Grey Kangaroos

For more detail please refer to Sections 3.4 to 3.8 in the ACT Kangaroo Management Plan

Some of the ecological communities of the ACT originally occurred on land highly favoured for agricultural or urban development. As a result, the remnants of lowland natural temperate grassland and yellow-box red-gum woodland communities are now small, and highly fragmented.

Their environment has also been changed in other important ways, including the removal of the top predators such as Thylacines and dingoes. Hunting by Aborigines and early Europeans has also been suppressed. Around the world, the loss of top predators has often been regretted. For example, efforts are now being made to return wolves and bears to the mainland United States of America. In the absence of a predator level, large herbivores like eastern grey kangaroos can maintain the ground layer vegetation in a permanently eaten down condition.

Striped legless lizard

This vegetation is also home for small animals such as grassland earless dragons and striped legless lizards. When eaten down, the grasslands no longer provide shelter from predators for these small animals leading to a decline in their populations and potentially localised extinction. To protect the remaining populations of these small animals and rare plants, kangaroo grazing needs to be kept at moderate levels.

The effect on grassland reptiles from defoliating a grassland, is comparable to the effect on a koala population from defoliating a forest, as detailed in this diagram:

Grassland Conservation Densities

For the conservation of endangered grassland ecosystems it is desirable to maintain grassland conservation densities. This means kangaroo densities need to be maintained in a range of approximately 0.6 to 1.5 kangaroos per hectare in grasslands. For grassy woodland areas a lower density is likely to be optimal.

Refer to the ACT Kangaroo Management Plan for more detail on the issues summarised above. The Plan contains references to hundreds of scientific publications underlying its policies and a helpful glossary of terms.