Edge effects created by fenced conservation reserves benefit an invasive mesopredator
Hugh McGregor
A B C G , John Read D , Christopher N. Johnson A B , Sarah Legge A , Brydie Hill C E and Katherine Moseby C F
+ Author Affiliations
- Author Affiliations
A National Environmental Science Program Threatened Species Recovery Hub, Centre for Biodiversity and Conservation Science, University of Queensland, St Lucia, Qld 4075, Australia.
B School of Natural Sciences, Private Bag 55, University of Tasmania, Hobart, Tas. 7001, Australia.
C Arid Recovery, PO Box 147, Roxby Downs, SA 5725, Australia.
D Ecological Horizons Pty Ltd, PO Box 207, Kimba, SA 5641, Australia.
E Flora and Fauna Division, Department of Environment and Natural Resources, PO Box 496, Palmerston, NT 0830, Australia.
F University of New South Wales, Sydney, NSW 2052, Australia.
G Corresponding author. Email: hugh.mcgregor@utas.edu.au
Wildlife Research 47(8) 677-685 https://doi.org/10.1071/WR19181
Submitted: 4 October 2019 Accepted: 18 March 2020 Published: 6 July 2020
Abstract
Context: Fenced reserves from which invasive predators are removed are increasingly used as a conservation management tool, because they provide safe havens for susceptible threatened species, and create dense populations of native wildlife that could act as a source population for recolonising the surrounding landscape. However, the latter effect might also act as a food source, and promote high densities of invasive predators on the edges of such reserves.
Aims: Our study aimed to determine whether activity of the feral cat is greater around the edges of a fenced conservation reserve, Arid Recovery, in northern South Australia. This reserve has abundant native rodents that move through the fence into the surrounding landscape.
Methods: We investigated (1) whether feral cats were increasingly likely to be detected on track transects closer to the fence over time as populations of native rodents increased inside the reserve, (2) whether native rodents were more likely to be found in the stomachs of cats caught close to the reserve edge, and (3) whether individual cats selectively hunted on the reserve fence compared with two other similar fences, on the basis of GPS movement data.
Key results: We found that (1) detection rates of feral cats on the edges of a fenced reserve increased through time as populations of native rodents increased inside the reserve, (2) native rodents were far more likely to be found in the stomach of cats collected at the reserve edge than in the stomachs of cats far from the reserve edge, and (3) GPS tracking of cat movements showed a selection for the reserve fence edge, but not for similar fences away from the reserve.
Conclusions: Invasive predators such as feral cats are able to focus their movements and activity to where prey availability is greatest, including the edges of fenced conservation reserves. This limits the capacity of reserves to function as source areas from which animals can recolonise the surrounding landscape, and increases predation pressure on populations of other species living on the reserve edge.
Implications: Managers of fenced conservation reserves should be aware that increased predator control may be critical for offsetting the elevated impacts of feral cats attracted to the reserve fence.
Additional keywords: conservation management, invasive species, wildlife management.
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