immigration

Understanding rates of reinvasion is critical for determining what drives ship rat population recovery following large-scale control operations. We radio-tracked 23 adult ship rats on the edge of a forested area where rats had been suppressed by aerial compound 1080 in the Hollyford Valley, Fiordland. Eleven individuals died within two months of collaring and two individuals were never detected again, leaving us with data from 10 rats.

We examined spatiotemporal changes in rat tracking indices following large-scale (>10 000 ha) pest control using aerial applications of sodium monofluoroacetate (1080) baits in Tararua Forest Park, North Island, New Zealand. Population control of rats appeared effective, with few to no rat tracks recorded in treatment areas during the 6 months after control. However, the rat tracking index increased rapidly after that, and 24–30 months after control, rat tracking indices in treated areas exceeded those in the non-treated areas.

Hourly kill-rates and encounter-rates for hunters of feral goats (Capra hircus) provided linear indices of goat population size in a 638 ha area of forest and grasslands in Marlborough. The goat population of about 108 animals was reduced to near zero in 105 hours of hunting effort on 11 days at a cost of about $8.20 ha-1. However, goats from the surrounding areas soon recolonised the study area as 19 were shot in 21 hr and 14 in 24 hr 10 and 13 months after the study, respectively.

Despite periods of extensive government-funded control, fluctuating commercial exploitation and ongoing recreational hunting, little is known about how red deer (Cervus elaphus scoticus Lönnberg) in New Zealand respond to the cessation of harvesting in terms of population growth rate and resource use. We describe the population dynamics and resource use of red deer in a montane catchment over 5 years (1962–67) following cessation of intensive government-funded control in 1961.