Predation at North Island Robin Petroica australis longipes and North Island Tomtit Petroica macrocephala toitoi nests was studied in New Zealand over the 1993/94 breeding season to determine impacts of predators. Infra-red, time-lapse video photography and sign left after predation were used to identify predators at nests. Accurate estimates of predation rates depended on early detection of nests. Previous studies of predation may have greatly under-estimated predation rates and therefore predation impacts. Predation was patchy and intense, resulting in failure to produce young in some territories despite up to ten nesting attempts. A maximum of 82% of nests were preyed on (n = 65; 95% confidence interval 72.4%?90%) and Ship Rats Rattus rattus were probably responsible for at least 72% (95% confidence interval 57.4%?84.4%) of predations. Nine of 24 territories lost breeding females, mainly to Ship Rats, which significantly impacted on population productivity. Ship Rat predation was equally intense at exposed and concealed nests (at the site and patch levels). Predation attributed to avian predators was strongly correlated with exposed nests (at the patch level). Restoration of New Zealand's threatened forest bird communities is dependent on a commitment to further research into the significance of different predators and predation impacts on bird populations.

In New Zealand, five of the six endemic bird species that breed primarily in South Island braided river beds are classed as threatened. A major cause of decline for these species is predation by introduced mammals, and predator-trapping programs are undertaken in the braided rivers of the Mackenzie Basin to protect them. Trapping programs carried out between September 1997 and April 2001 provided the opportunity to investigate predator diet from the gut contents of 375 cats (Felis catus), 371 ferrets (Mustela furo) and 86 stoats (Mustela erminea). As a percentage frequency of occurrence of the main prey items, cat diet consisted of lagomorphs (present in 70% of guts), birds (in 47%), lizards (30%) and invertebrates (36%). Ferret diet consisted of lagomorphs (69%) and birds (28%). Stoat diet consisted of lagomorphs (50%), birds (51%), lizards (21%) and invertebrates (23%). The frequency of occurrence of birds in all three predators was higher in the spring/summer of 1997 – immediately after rabbit haemorrhagic disease (RHD) was introduced – than in any other previous diet study on these braided rivers. This suggests that RHD did lead to increased predation pressure on birds, at least in the short term.

There is a strong case for monitoring future changes in the status of the polecat in Britain, and the system tested in this study should contribute usefully to a long-term national monitoring strategy.I am very grateful to all the volunteers who contributed so much enthusiasm and hard work to this exercise. I thank all landowners who permitted us to trap on their land. The staff of English Nature and the Countryside Council for Wales kindly supplied maps. Paul Chanin gave helpful advice. Don Jefferies, John Messenger and an anonymous referee made helpful comments on a draft of this paper. of British mammals other than cetuceans. Peterborough: Joint Nature Conservation Committee. Nature Conservation Committee. Munzm. Rev. 7(3/4): 95-1 16. putorius) in Britain. Envircm. Polhit. 3: 279-282. meles setts in Essex. Mamni. Rev. 21(2): 5 1-66. Eleven radio-tagged stoats (Mustela ermineu) and one weasel (M. nivalis) died of secondary poisoning following Talon 20 PTM (20 ppm brodifacoum) poisoning operations which killed mice (Mus niusculus), ship rats (Rattus rattus) and probably brushtail possums (Trichomrus vulpecicla) in a New Zealand beech (Nothqfagus) forest. This poisoning method could be an especially useful way of restoring New Zealand native bird populations because it kills several predator species in one 864 COMMUNICATIONS FROM THE MAMMAL SOCIETY -NO. 75operation. Potential unwanted side-effects must be researched before its routine use. This research also demonstrates the potential hazards of second-generation anticoagulant rodenticides to conservation of rodent predators in Europe.

An intensive predator trapping programme was implemented in the upper Waitaki Basin, New Zealand from October 1997 to January 1998. The aim of the programme was to prevent increased predation on vulnerable braided river fauna following decline in rabbits due to rabbit haemorrhagic disease (RHD). Fourteen sites were trapped using a standardised method, and trap catch results provided a relative index of predator abundance. In 101 650 trapnights, 1067 hedgehogs, 328 ferrets, 196 cats, 96 rats and 69 stoats were caught. Predator guilds varied among sites and guild composition tended to change through time; for example, stoat and rat catch rates increased. Cat and ferret catch rates increased in the last month of trapping, which suggested that juvenile dispersal and immigration by adult predators from surrounding areas were high. This study provides baseline information on predator abundance and predator guilds in the upper Waitaki Basin against which future trapping programmes can be compared, in order to assess changes in predator populations since the introduction of RHD.

Two different brodifacoum (Talon 20 P™) poisoning regimes effectively killed 100% of resident radio-tagged stoats (Mustela erminea) by secondary poisoning in a New Zealand Nothofagus forest when mice (Mus musculus) were scarce. Resident possums (Trichosurus vulpecula) and ship rats (Rattus rattus) were also killed. The relative importance of different prey species as sources of poison for stoats has not been clearly identified but availability of poisoned prey will determine the efficacy of secondary poisoning in years of low prey abundance. Tracking tunnels did not accurately measure the decline in the stoat population and were probably influenced by immigrant stoats that were kill-trapped and contained high levels of poison. This study corroborates the findings of several other similar studies that secondary poisoning using brodifacoum effectively kills stoats.