A theoretical assessment of the ability of bird species to recover from an imposed reduction in numbers, with particular reference to 1080 poisoning

A consideration of the composition of bird diets, and the list of bird species found dead indicates that most New Zealand land bird species risk being killed by feeding directly on baits poisoned with Compound 1080 or by eating poisoned prey. Theoretically, if a population of a species is heavily reduced, its ability, or inability, to recover can be predicted from a consideration of its reproductive and dispersal capacities. Species with poor reproductive potential and poor dispersal have a high risk of non-recovery, e.g., the three species of kiwi, the takahe, kakapo, laughing owl, bush wren, rock wren, fernbird, yellowhead, stitchbird, saddleback, kokako, and New Zealand thrush. Species with either poor reproduction or poor dispersal are medium risk species, e.g., the New Zealand falcon, weka, New Zealand pigeon, kaka, kea, the three species of parakeets, the morepork, rifleman, brown creeper, whitehead, and robin. Species with good reproductive and good dispersal capacities are low risk species, e.g., the Australasian harrier, pukeko, kingfisher, welcome swallow, New Zealand pipit, grey warbler, fantail, tit, silvereye, bellbird, and tui. The implications of this classification are discussed in relation to forest management practice.