Going the distance on kangaroos and water: A review and test of artificial water point closures in Australia

Abstract

Grazing by overabundant herbivores can cause land degradation and reduce biological diversity. Across arid and semi-arid Australia, predator control, pasture improvement, and artificial water points (AWP) have contributed to increased populations of kangaroos and wallaroos (Macropus spp.). Control efforts (e.g. culling, predator reintroduction, fertility control) can be expensive, controversial and/or unsustainable in the long term. Closure of AWP is an alternative. We reviewed closures in Australia and found experimental tests have been few, and results unconvincing for two main reasons. Firstly, no study has tested AWP closures over distances influential to kangaroos. We identified seven AWP closure experiments in Australia. Five did not generate areas beyond 5 km from water and two used a method ineffective for excluding kangaroos. Secondly, post-closure monitoring has frequently been too short to detect changes amongst natural environmental fluctuations. Our own experimental AWP closure did not influence kangaroo populations and reaffirmed that kangaroo densities are dictated by food availability in Australia's water rich rangelands. Larger experiments are needed with systematic AWP closures that generate water remote landscapes, preferably exceeding 10 km from water. Monitoring must span dry, hot periods of below average rainfall when kangaroos are most likely dependent on drinking water.