Methods

Seven trap lines have been established; the lowest traverses the forest/pasture margin, the highest traps the alpine scrub zone (Fig. 1). The upper lines run between two adjacent ridge systems and all lines are aligned so as to intersect the numerous forest-to-pasture possum runs. Two hundred and fifty wire-mesh, live-capture traps are permanently positioned on sites with favourable possum sign. These traps have been set for three fine nights per month since August 1975, and produce monthly catches of between 250 and 350 animals.

Newly captured animals are anaesthetised with ether, identified with an ear tag and tattoo number on the inner ear, then weight, length, reproductive status and condition of teeth are recorded. On subsequent captures we weigh animals and determine their reproductive status without using anaesthetic. Non-kill snares have also been set in the lower regions of the hill at different times.

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