New Zealand Journal of Zoology abstracts
Movements by stoats (Mustela erminea) and ferrets (M.
furo) through rank grass of yellow-eyed penguin (Megadyptes
antipodes) breeding areas
H. RATZ
Zoology Department
University of Otago
P.O. Box 56
Dunedin, New Zealand
Abstract Predation by introduced stoats (
Mustela
erminea) and ferrets (
M. furo) may be contributing to the decline of
yellow-eyed penguins (
Megadyptes antipodes) on the South Island of New
Zealand. Areas of rank grass were established in the hope of reducing predation
by physically excluding predators from penguin breeding areas. This paper
describes a foot-print tracking study which showed that stoats and ferrets were
recorded twice and ten times respectively more often in rank grass than in
grazed pasture. Stoats moved evenly throughout the rank grass, but ferrets
restricted their movements to tracks through the rank grass. Ferrets approached
penguin nests over 12 times more often than randomly selected sites in grazed
pasture, particularly in spring when the penguin chicks are vulnerable to
predation. Stoats appeared to avoid areas with high ferret abundance. Mice
(
Mus musculus), an important prey of these predators, were recorded 5-17
times more often in the ungrazed areas than in grazed areas. The concentration
of stoats, ferrets and mice in the penguin breeding areas surrounded by rank
grass increases the number of encounters between penguin chicks and predators,
and so may increase rather than decrease the risk of predation of yellow-eyed
penguins and other ground nesting birds.
Keywords ferret Mustela furo; footprints; grazed
pasture; habitat use; predation; rank grass; stoat Mustela erminea;
yellow-eyed penguin Megadyptes antipodes
Z99032
Received 23 August 1999; accepted 3 November 1999
PDF file of entire paper: medium quality (979K); (scanned from paper original: notes about this process)
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