Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats

Diet of mammalian predators in braided river beds in the central South Island, New Zealand

Elaine C. Murphy A D , Rachel J. Keedwell B , Kerry P. Brown C and Ian Westbrooke A
+ Author Affiliations
- Author Affiliations

A Department of Conservation, PO Box 13 049, Christchurch, New Zealand.

B 24 Buick Crescent, Palmerston North, New Zealand.

C Department of Conservation, PO Box 5086, Wellington, New Zealand.

D Corresponding author. Email: emurphy@doc.govt.nz

Wildlife Research 31(6) 631-638 https://doi.org/10.1071/WR03033
Submitted: 28 April 2003  Accepted: 16 August 2004   Published: 23 December 2004


In New Zealand, five of the six endemic bird species that breed primarily in South Island braided river beds are classed as threatened. A major cause of decline for these species is predation by introduced mammals, and predator-trapping programs are undertaken in the braided rivers of the Mackenzie Basin to protect them. Trapping programs carried out between September 1997 and April 2001 provided the opportunity to investigate predator diet from the gut contents of 375 cats (Felis catus), 371 ferrets (Mustela furo) and 86 stoats (Mustela erminea). As a percentage frequency of occurrence of the main prey items, cat diet consisted of lagomorphs (present in 70% of guts), birds (in 47%), lizards (30%) and invertebrates (36%). Ferret diet consisted of lagomorphs (69%) and birds (28%). Stoat diet consisted of lagomorphs (50%), birds (51%), lizards (21%) and invertebrates (23%). The frequency of occurrence of birds in all three predators was higher in the spring/summer of 1997 – immediately after rabbit haemorrhagic disease (RHD) was introduced – than in any other previous diet study on these braided rivers. This suggests that RHD did lead to increased predation pressure on birds, at least in the short term.


We thank all the people who helped in the predator-trapping program in 1997/98, and thanks in particular to Peter Cook and the kaki team for providing predator guts from the kaki-trapping program 1998–2000. We offer thanks to all the landholders who cooperated with the trapping program, and the Department of Conservation staff of the Twizel Area and Canterbury Conservancy Offices. Thanks also to Chris Morse and Fraser Maddigan, who helped with some of the diet analyses. John Dowding, Michael Ryan and two referees made useful comments on earlier versions of this manuscript.


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Appendix 1.  Frequency of occurrence of the major prey items (lagomorph, bird, lizard and invertebrate) found in guts of 197 cats, 213 ferrets and 60 stoats caught from November 1997 to January 1998 at 13 sites in the Mackenzie Basin, South Island, New Zealand
Lago. = lagomorph, Invert. = invertebrate

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