DISTRIBUTION AND ABUNDANCE OF SMALL MAMMALS IN RELATION TO HABITAT INPUREORA FOREST PARK

Populations of ship rats (Rattus rattus), Norway rats (R. norvegicus), feral house mice (Mus musculus), stoats (Mustela erminea), weasels (M . nivalis), and ferrets (M. furo) were sampled with killtraps every th ree months from November 1982 to November 1987 in logged and unlogged native forest and in exotic plantations of various ages at Pureora For est Park, central North Island. Mice (n=522 collected) were fewest in unlogged native forest, more abundant in road edge cutover forest, and most abundant in a young (5-10 year old) plantation. Traps catching m ost mice were set in dense ground cover under a low, sparse canopy. Sh ip rats (n=1793) were absent from the young plantation, present but no t abundant in older exotic forest, and abundant in all native forest r egardless of logging history. Traps set on warmer, steeper sites caugh t most ship rats, and those set in early successional habitats caught fewest. There was a marked reciprocal relationship between the distrib utions of ship rats and of mice: the proportion of mice in the total c atch of rodents decreased significantly at the least, disturbed forest sites (P<0.001). Most (81%) Norway rats (n=43) were caught in a singl e trap in unlogged native forest on the bank of a stream. Stoats (n=57 ) were most abundant in the older exotic plantations; weasels (n=16) i n the young plantation and along road edges in native forest; and ferr ets (n=11) in unlogged native forest. Hedgehogs (n=290) were common in unlogged native forest far from any roads and also in older exotic fo rest. Our data suggest that selective logging and conversion to exotic s have different effects on each of the six species we monitored. We h ypothesise that (1) selective logging is likely to stimulate temporary increases in the numbers of mice and weasels, but not rats or stoats, and (2) after conversion to exotic forest, mice and occasionally weas els will be abundant at first but will gradually be replaced by ship r ats and stoats as the forest matures.