Mason Bay rat trapping

Department of Conservation —  21/05/2012

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.

Red-crowned kakariki

NZDA trappers re-baiting a trap at Mason Bay

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.

Looking South across the trapped area from the Big Sand Pass

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.

For more information about the project please contact the Southland NZDA or DOC Stewart Island Field Centre.

3 responses to Mason Bay rat trapping

    Jamie Metcalf 16/01/2013 at 11:01 am

    Hi there! I simply want to give a huge thumbs up for the good information
    you will have right here on this post. I might be coming again to your weblog for more


    Ok, Ulva has Saddlebacks and occaisionally Sirocco. But really I didn’t notice significantly more birdlife there than I have enjoyed on my extensive tramping on the rest of Rakiura every year for the past 12 years.


    As a keen possum and mustelid trapper who is heavily involved in an extensive rat poisoning project, I find it hard to believe that rat trapping would make a stitch of difference given that rats breed up every 6 weeks!!! Having hiked most of Rakiura and seeing first hand the damage deer and possum browse is causing and the lack of birds life on most of the tracks caused no doubt by feral cats and rats… I and other like minded people know the only solution is for DOC to get some balls, tell the Deer Stalkers Association that their rat traps are a useless waste of time and the only real solution is to do significant 1080 drops to save this so called National Park! If Rakiura residents and Doc don’t hurry up and pull their head’s in, Ulva Island will continue to be reinvaded by rats and the islands only revenue Tourism will be lost….