The effect of fox control on mammal populations in an outer urban conservation reserve.

Abstract

European red foxes were systematically removed from a 370 ha conservation reserve on Melbourne?s urban fringe between December 2003 and September 2005. Activity indexes monitored throughout the removal phase indicated that the fox population declined dramatically when poison baits were available and then increased again predictably during winter and summer each subsequent year. Three alternate indices of fox activity were highly synchronous throughout the study suggesting that the bait-removal index used widely in Australia may provide a reliable measure of overall fox activity in small urban reserves. With monitoring and strategic baiting, fox activity was maintained at a fraction of its pre-control level. Activity indices for several other species of mammal also appeared to respond to the reduced density of foxes at the site after 2003. Southern brown bandicoots (Isoodon obesulus) and swamp wallabies (Wallabia bicolor) increased in both activity and range after the reduction in the fox population indicating that fox predation may act to limit both the total size of populations and types of vegetation occupied by indigenous mammals in small patches of remnant vegetation.