New Zealand Journal of Zoology abstracts
Z00035Received 20 June 2000; accepted 4 October 2000
Population biology of the ship rat and Norway rat in Pureora Forest Park,
1983-87
J. G. INNES
Landcare Research
Private Bag 3127
Hamilton, New Zealand
C. M. KING
Department of Biological Sciences
University of Waikato
Private Bag 3105
Hamilton, New Zealand
M. FLUX
230 Belmont Hill Road
Lower Hutt, New Zealand
M. O. KIMBERLEY
New Zealand Forest Research Institute
Private Bag 3020
Rotorua, New Zealand
Abstract Populations of ship rats (
Rattus rattus) and
Norway rats (
R. norvegicus) were sampled over the five years 1983-87 at
Pureora Forest Park, by Fenn and rat kill-traps every three months. Fenn and
rat traps recorded similar capture rates in comparable habitats, although Fenns
caught more heavy and fewer young rats. Ship rats (n = 1793 collected) were
more abundant, heavier and larger in native forest, regardless of logging
history, than in exotic forest of any age. Young ship rats (age classes 1-3)
were most abundant in unlogged interior native forest, and in autumn and winter
after summer and autumn breeding. Capture rates declined after peaking in 1985,
probably due to reduced recruitment of young rats following lower pregnancy
rates in adult females. The irregular annual seasonal cycle of reproduction and
abundance observed at Pureora is the same as that described for non-commensal
ship rat populations elsewhere in New Zealand and the world. Thirty five of 43
Norway rats collected came from a single trap by the Waipapa Stream, apparently
set near a permanent colony. Pregnant female Norway rats were trapped in every
season, suggesting year-round breeding. This implies that both species can
recover rapidly after control operations conducted at any time of year, but
especially in spring and summer. Future research should include manipulative
exploration of factors limiting ship rat abundance and Norway rat
distribution.
Keywords rats; Rattus rattus; Rattus
norvegicus; New Zealand; Pureora Forest Park; native podocarp forest;
exotic forest; measurements; colour morphs; population structure; age;
reproduction; recruitment
New Zealand Journal of Zoology, 2001, Vol. 28: 57-78
0301-4223/00/2801-0057 $7.00/0 (c) The Royal Society of New
Zealand 2001
PDF file of entire paper: medium quality (1516K); (scanned from paper original: notes about this process)
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