By Paul Jacques
2011-12 has been another successful season of rat trapping in Mason Bay, Stewart Island/Rakiura. Rat capture dropped steadily from 165 in August down to just 8 in December, providing a welcome break from rat predation for breeding birds such as red-crowned kakariki (pictured), bellbird, brown creeper and Stewart Island robin. By the end of the season the rat tracking rate was 0% within the trapped area compared to 30% in un-trapped forest nearby, good evidence that the 331 kills this season have again reduced the rat population significantly.
Between August and December each year five teams of keen NZDA volunteers head to the Bay to check, re-bait and maintain the network of over 300 traps. DOC helps out with travel costs and also provides technical assistance such as running tracking tunnels to measure rat abundance at the start and end of each season.The Mason Bay rat trap network is a co-operative project between the Southland Branch of the New Zealand Deerstalkers Association and DOC Stewart Island Field Centre. The traps are run during the bird breeding season with the aim of increasing the productivity of native birds by reducing rat numbers at this crucial time of the year.
The traps protect about 200 ha of coastal podocarp/broadleaf forest situated between the nationally important Mason Bay sand dunes and the freshwater swamp. While controlling rats in this spectacular environment the volunteers have the opportunity to hunt both red and white-tailed deer and also have an excellent chance of spotting a kiwi.
This season’s trapping will begin again in August. This year we plan to trial a bird monitoring method used by other community groups around New Zealand, to measure changes in bird numbers over time in response to trapping. We will also be looking into options for feral cat control to run alongside the rat network.