The Use of Surrounding Farmland by Western Gray Kangaroos Living in a Remnant of Wandoo Woodland and Their Impact on Crop Production.

A population of 95-200 western grey kangaroos (Macropus fuliginosus) was studied for 11 years in Western Australia. The population occupied 300 ha of wandoo woodland and had easy access to surrounding farmland. Kangaroo use of farmland varied over the period of study: 27-37% of the population was seen on farmland during the first 6 years, and the variation was not related to population size. In the last 5 years 15-23% of the population was seen on farmland. One area of farmland was initially used in the first 4 years by an av. of 34 animals/night. The number declined to 22-23 in the next 2 years when cattle numbers were increased, and to 3 animals in the 5 years after culling. It is suggested that numbers in the area remained low because of the high fidelity individuals had to home ranges and because of slow dispersion within the population. It was concluded that localized culling could have a prolonged effect. Individuals varied in their use of farmland: some animals went onto farmland to feed during most nights; some went rarely, if at all. The impact of the kangaroos on crop production was assessed by planting various crops in locations adjacent to the woodland. This population showed a marked preference for lupin crops, followed by barley, wheat and oats. The biomass of lupin crops within 100 m of the boundary between woodland and farmland were reduced by up to 95%; the max. reduction with oats was 24%. Because the kangaroos rarely moved more than 400 m from the woodland, crops sown at this distance were unaffected. Ringlock fencing topped by 2 strands of barbed wire with a plain wire in between virtually eliminated damage to lupin crops.