Predator-prey communities are ubiquitous in ecology, but introduced predators can drive native species to extinction within island systems, prompting the eradication of such exotics. Ecological theory predicts that elimination of top-introduced predators from islands can lead to the counterintuitive decline of native prey populations through the ecological release of smaller introduced species in a process termed ''mesopredator release.'' We show, in accordance with mesopredator release theory and counter to conservation goals for a New Zealand island reserve, that initial eradication of cats on Little Barrier Island led to reduced breeding success of Cook's petrels, which also are vulnerable to predation by a mesopredator, the Pacific rat. The rat's impact on prey productivity varied with elevation within the island. Rat eradication was followed by a rise in petrel productivity, in support of both ecological theory and practical conservation management goals. It appears that interactions among introduced predators, native prey, and environmental gradients can drive counterintuitive and spatially heterogeneous responses to predator eradications from islands. Location-specific, ecosystem-level understanding is essential for predicting the outcomes of such restoration management techniques.habitat gradients ͉ introduced predator eradications ͉ island restoration ͉ trophic cascade ͉ Cook's petrel

No abstract

The importance of artificial nest boxes for North Island saddlebacks (Philesturnus carunculatus rufusater) on Tiritiri Matangi Island has increased significantly, suggesting that "natural" nesting cavities are now a limited resource for this growing population. The design and position of artificial nest boxes directly affects the likelihood of saddleback use for nesting: small boxes (0.005 and 0.0lm3 ) with large (140-160 mm high) north facing openings had the highest probability of being used. One of the disadvantages of using artificial nest boxes in conservation management is the potential for parasite build-up. Two species of mesostigmatid mites were found in the artificial nest boxes used by saddlebacks on Tiritiri Matangi Island. One was an undescribed species of Dermanyssid mite the other was Ornithonyssus bursa, the fowl mite. The numbers of mites detected increased over the saddleback nesting cycle from September to December. However, our results strongly suggest that, for saddlebacks, no negative correlations exist between mite abundance and chick weight, fledging date, or the number of fledglings produced. Mite abundance was extremely variable and did not correlate with nest box temperature or relative humidity.

No abstract