Goat movement patterns inform management of feral goat populations in semiarid rangelands

Abstract

Abstract ContextFeral goats (Capra hircus) are a significant pest species throughout southern Australia. They threaten rare plants, contribute to soil erosion, compete with domestic stock, and are implicated in the decline of several native herbivores. Feral goats are a declared pest and control is often implemented. AimsWe fitted feral goats with GPS collars in semiarid South Australia to determine whether they could provide valuable information for regional management. MethodsNineteen feral goats (6 males and 13 females) were fitted with GPS collars between 2009 and 2018. Kernel-density estimates (KDE) were used to estimate annual and seasonal home range and core areas and habitat selection. The effect of monthly rainfall, daily maximum temperatures, and watering points on movement patterns was investigated. Key resultsStock watering points and rock holes were used by some radio-tracked goats intermittently when available; however, goats survived and reproduced without the use of these water sources. The use of the radio-collared goats as Judas goats helped facilitate the removal of 9725 goats from a 50000-ha area over 8 years. There was no significant difference between male and female annual or seasonal home ranges, with 95% MCP annual ranges of 11533ha and 15996ha for males and females respectively. Summer ranges were smaller than winter ranges. There was no difference in daily distance moved between sexes (average 3.4km), but goats moved further in low-rainfall periods. Goats spent most of their time in mallee woodlands, the dominant habitat type available, but preferred shrubland of >1-m height and used less mallee woodland and shrubland of <1-m height than was expected from availability. During hotter periods, these habitat preferences became more distinct. ConclusionsTo reduce goat abundance on a property, active control and waterpoint closure need to extend more than 15km from property boundaries, and shrubland habitat of >1-m height should be targeted for control after rainfall events when goats move less. Radio-collared goats provided important habitat-preference information to inform priority areas for goat control remote from water sources. ImplicationsClosing artificial watering point and regular trapping and mustering at remaining waters is insufficient to remove residual goat herds without additional targeted control in preferred habitat.