Pāteke (<i>Anas chlorotis</i>) population trends in response to predator control on Great Barrier Island and Northland, New Zealand

Pāteke, brown teal (<i>Anas chlorotis</i>) were until recently restricted to two key strongholds in northern New Zealand: Great Barrier Island and eastern Northland. In 2000, we applied predator control at two sites within the strongholds. We analysed three decades of summer pāteke flock count data collected at ‘trapped’ and ‘untrapped’ locations to assess numerical pāteke response to predator control. Using piecewise regression, we found that Northland pāteke at trapped sites increased from 130 individuals before predator control, to 341 by 2015. Conversely, pāteke in untrapped areas in Northland remain low. Compared with the Northland trapped site, there was a slower rate of population increase in the predator treated site at Okiwi on Great Barrier Island; 286 individuals at trapped sites before predator control and 390 individuals in 2015. Pāteke numbers at untrapped sites on Great Barrier Island also increased, from 214 to 316 individuals. Cause of death analyses confirm that predation is a significant factor at trapped sites in Northland (87% of pāteke deaths) and Okiwi (56% of deaths), with starvation accounting for an additional 16% of identified causes of death at Okiwi. Access to sufficient food sources may be limiting at Okiwi, but overall the provision of predator control has benefitted pāteke populations.褐水鸭（Pāteke，*Anas chlorotis*）曾一度仅残存于新西兰北部两处核心庇护种群的栖息地：大巴里尔岛（Great Barrier Island）与北地东部区域。2000年，我们在该庇护区域内的两处位点开展捕食者管控工作。我们对30年间采集自"已实施捕食者管控"与"未实施捕食者管控"位点的夏季褐水鸭集群计数数据进行分析，以评估褐水鸭种群对捕食者管控的数量响应。 借助分段回归（piecewise regression）分析，我们发现北地区域内已实施捕食者管控位点的褐水鸭种群数量从管控前的130只增长至2015年的341只。与之相对，北地未实施管控区域的褐水鸭种群数量始终处于低位。 相较于北地的管控位点，大巴里尔岛奥基维（Okiwi）的捕食者管控位点种群增长速率相对平缓：管控前种群数量为286只，2015年增至390只。大巴里尔岛未管控位点的褐水鸭种群数量同样有所增长，从214只升至316只。 死因分析结果证实，捕食作用是北地管控位点（占褐水鸭死亡个体的87%）与奥基维（Okiwi）位点（占56%）的主要致死因素；此外在奥基维位点，另有16%的已确认死因为饥饿。奥基维区域的褐水鸭种群或面临食物资源不足的限制，但总体而言，捕食者管控措施已对褐水鸭种群起到了积极保护作用。