New Zealand Journal of Zoology abstracts
The relative importance of Australian magpies (Gymnorhina tibicen)
as nest predators of rural birds in New Zealand
D. Morgan
J. R. Waas
Department of Biological Sciences
University of Waikato
Private Bag 3105
Hamilton, New Zealand
dm30@waikato.ac.nz
J. Innes
Landcare Research
Private Bag 3127
Hamilton, New Zealand
Abstract Australian magpies (Gymnorhina tibicen)
have been recorded as predators at nests of other birds in New Zealand
but their importance as a predator in rural areas, where they are most
common, has not been previously quantified. We continuously monitored
38 nests of seven species in rural areas over two successive breeding
seasons using time-lapse video recording to determine the proportion
that were preyed on by magpies compared to other animals in this
ecosystem. Twenty-two lethal events were recorded over the two breeding
seasons; magpies were responsible for only one of these. A further
eight scavenging events were also recorded; magpies were not
responsible for any of these. Harriers (Circus approximans),
ship rats (Rattus rattus), and cats (Felis catus) were
the main predators and were responsible for 36, 32, and 23% of lethal
events respectively. A pukeko (Porphyrio porphyrio) was also
recorded preying on nest contents on one occasion. Other known nest
predators such as Norway rats (Rattus norvegicus), possums (Trichosurus
vulpecula), hedgehogs (Erinaceus europaeus) and ruru (Ninox
novaeseelandiae) did not appear in any recorded frame although
present in the study areas. Our results suggest that magpies are not
serious nest predators in rural areas in comparison to ship rats, cats,
and harriers, and that controlling magpies in rural areas will not
significantly improve the nesting success of other birds.
Keywords Australian magpie; nest mortality; nest
predation; rural habitat; time-lapse recording; video
Z05031; Received 23 August 2005; accepted 4 November 2005; Online
publication date 24 February 2006
New Zealand Journal of Zoology, 2006, Vol. 33: 17–29
0301–4223/06/3301–0017 © The Royal Society of New Zealand 2006
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