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.

No abstract

No abstract

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.

No abstract

No abstract

We used videocameras to monitor 39 nests of the Banded Dotterel (Charadrius bicinctus), a ground-nesting plover endemic to New Zealand that suffers from predation by introduced mammals. To test whether monitoring nests increased the chances of nests being visited by predators, 22 of the video-monitored nests were approached on foot daily to simulate conventional monitoring and 17 unapproached nests were monitored using videocameras only. The proportions of approached nests (46%) and unapproached nests (41%) that were visited by predators did not differ significantly, nor was there any evidence that predators used human scent trails to locate nests. This study provides some evidence that monitoring Banded Dotterel nests by regularly checking them does not influence their risk of predation.Control de Nidos y Visita de Depredadores a Nidos de Charadrius bicinctusResumen. Usamos cámaras de video para controlar 39 nidos de Charadrius bicinctus, un ave endémica de Nueva Zelandia que anida en el suelo y es depredada por mamíferos introducidos. Diariamente nos acercamos a pie a 22 de los nidos controlados con cámaras para simular el modo convencional de seguimiento, y controlamos 17 nidos usando sólo las cámaras y sin acercarnos a ellos con el fin de examinar si el control convencional de nidos incrementa la probabilidad de visita de depredadores. La proporción de nidos personalmente examinados (46%) y no examinados en persona (41%) que fueron visitados por depredadores no difirió significativamente, y no hubo evidencia que los depredadores usan rastros de olores humanos para localizar los nidos. Este estudio sugiere que controlar regularmente los nidos de Charadrius bicinctus no influencia su riesgo de depredación.

No abstract