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EnviroNorth > All Regions > Feral Animals > Donkeys, horses and cattle

Donkeys, horses and cattle

Overview

Mick Everett from AGWEST fits a feral donkey with a tracking collar

Mick Everett from AG WEST fits a feral donkey with a tracking collar in the Kimberley
Photo: Andrew Johnson, AG West

Wild donkeys, horses, cattle and, in the drier areas, camels, are all avid grazers in the tropical savannas. They can compete with native herbivores and also with stock for forage and water (although camels are probably less competition than horses and donkeys).

Feral donkeys in Western Australia are the descendants of pack and draft animals used in the development of the Kimberley area in the late 19th century. In central and northern Australia there is an estimated 300,000 feral horses. To see a recent list of research findings on feral donkeys click here .

Impact on environment

Because of the selective nature of their grazing, for this can change the composition of plant species in an area. Donkeys and horses prefer certain plant species, and their heavy grazing on these species allows other plants — less palatable both to the ferals and to native animals — to proliferate. Eventually, large areas can become virtual monocultures.

This has effects throughout the ecosystem. Many native species, especially birds, rely on plant products for food. A diversity of plant species, setting seed at different times of the year, ensures a continuous food supply. But if only one or a few species remain, then seed or fruit may be abundant only at one time of the year, leaving the area virtually food-free the rest of the time. This simplification of the species richness in the region's plant cover is ecologists' main worry about feral grazers in the savannas.

In addition, the heavy hooves of these animals can cause soil erosion, especially if many animals are gathered in one area, such as happens around water sources in times of drought.