Carnivore resource subsidies to support predator reintroductions and mitigate threats to reintroduced prey

Abstract

The potential risk to threatened prey species is a real or perceived barrier to reintroducing carnivores to fenced or island conservation reserves. Supplementary feeding of reintroduced carnivores is a tool that may increase translocation success and ease predation pressure on prey populations at critical times. In 2020–2022, we monitored the activity of native prey, and the activity and diet of a reintroduced predator, the western quoll (Dasyurus geoffroii), around carcass feeding stations in an Australian fenced reserve. We compared camera detections of predators and prey at sites where carcass presence was manipulated (carcasses added, removed, or absent) over a period of 21 months. Quoll activity and detections increased around feeding stations when carcasses were added, while activity of small rodents and bilbies were reduced. Bandicoot detections at sites with carcasses were also reduced but only at sites where supplementary carcasses had been provisioned for >2 years. There were significant (rodents) and non-significant (bilbies, bandicoots) trends for less prey remains in scats collected close to feeding stations, suggesting prey behavioral avoidance rather than elevated hunting at feeding sites. In comparison, reptiles, also a quoll prey item, were higher in scats near feeding stations, suggesting reptile attraction to feeding stations where they are preyed on by quolls. Our results, combined with previously demonstrated reductions in mammalian prey abundance at a reserve-wide scale, suggest that carcass subsidies do not elevate hunting at local scales but could sustain or increase predator density at broad scales. Until further work is conducted, we advocate for only intermittent use of feeding stations during the immediate post-release period to help anchor and acclimatize predators to the release site, and during times of resource scarcity such as drought.