Proactive management of kangaroos for conservation and ecosystem restoration – Wild Deserts, Sturt National Park, NSW

Abstract

Kangaroo populations have increased significantly across Australia’s arid rangelands where the Dingo (Canis dingo) is excluded, with some of the highest concentrations in western New South Wales. Novel adaptive management tools are needed to conserve kangaroo (Macropus and Osphranter spp.) populations and avoid negative impacts to biodiversity, agricultural production and animal welfare associated with their overabundance. Kangaroo densities within the Wild Deserts ecosystem restoration project within Sturt National Park in western New South Wales exceeded 100/km2 in mid-2016, during an 18-year regional population high. Following mass population declines attributed to emigration, an estimated 7,700 (±2,100 SE) kangaroos died within the 350-km2 Wild Deserts site over an 8-month period during drought (December 2017–August 2018). Population trends recorded at Wild Deserts were similar to population declines recorded during annual aerial survey counts across western New South Wales over the same period. With New South Wales (NSW) National Parks and Wildlife Service, Wild Deserts developed a kangaroo management plan to avoid future catastrophic mortality from starvation and mitigate associated ecosystem impacts. Conservation management centred upon a 104-km2 Adaptive Management Zone, fenced to trial adaptive management of sustainable kangaroo populations and restore habitats for the reintroduction of locally extinct mammals. Kangaroos were removed from two 20-km2 exclosures, adjacent to the Adaptive Management Zone, to provide baselines against which kangaroo populations could be assessed under variable environmental conditions. To effect this management, we assessed the effectiveness of one-way weldmesh spear and flap gates to provide passive unidirectional movement through fences. Of 171 approaches by adult Red Kangaroos to spear gates, 57 resulted in successful exits, while none of 51 approaches resulted in return movements, supporting the utility of spear gates as a practical and effective tool for directional exits of kangaroos through fences.