Abel Tasman Birdsong Trust

Putting birdsong back in Abel Tasman
National Park

Projects and progress

2010

Insights from our science desk – Where to now with pest control?

With stoats now being regularly controlled (and rats taken as bycatch) by volunteers along the coastal track in the southern end of Abel Tasman National Park, the opportunity exists to look at how pest control in this area may be expanded.

Possum Control
Possums impact directly on native fauna via predation, and indirectly via the plants they eat. Possum numbers in the southern end of the Abel Tasman National Park are modest, but it makes good sense to reduce their population to levels that ensure their key prey and plant foods flourish.

The opportunity now exists to couple achievable possum control to the existing stoat trapping programme, by placing a kill-trap for possums alongside each stoat trap. Both stoat and possum traps could be serviced simultaneously, with little additional effort. The possum traps could also be baited for cats once a year, to provide for their limited control.

Rat control
Rats are thought to be more harmful directly and indirectly to native birds, reptiles and insects than possums. As well, any reduction of rat populations is also likely to reduce stoat populations as rats are their primary prey.

Rat numbers fluctuate annually, with years of heavy seed fall driving large increases in the numbers of rats and subsequently of stoats. Rat control focussed immediately adjacent to Adele and Fisherman’s Islands would provide additional protection for both islands by helping maintain low numbers of stoats on the adjacent mainland.

A line of killing devices set about 20 m apart along the bush edge behind the beach, and 1-2 lines 30 m apart into the forest would significantly reduce the population of rats between the coastal track and the foreshore. Control in late winter-early spring would provide protection for brooding and nestling birds, and if undertaken every 2-3 years, would allow a significant but beneficial cohort of young birds through into the population. Annual control would, of course, be better.

Kill-trapping or poisoning of rats with ground-laid bait is effective in controlling their numbers. Toxins with very limited secondary poisoning and residue problems are available.

Showing benefits
Volunteer trappers, concessionaires, and the public need to ‘see’ the benefits of any pest control work. Trapping results provides an index of animal abundance and a measure of ‘kill’. That said, the numbers of pests killed is not the aim of any control programme – rather it is to allow for the increase of native fauna and flora, and in this regard, bird counts in particular are critical to demonstrate the efficacy of the current trapping programme.

Five minute counts of birds are a useful tool but require trained counters. However, even single species counts along the coastal track by inexperienced folk will provide useful data.

The recent release of South Island robins on Adele Island and the likely move of some robins to the adjacent mainland provides an ideal opportunity for the public to input into the restoration programme by recording and reporting any robins they see on the mainland. Such information will provide useful data to back up ongoing pest control.

2009

The really exciting part: We start protecting birds from predators and re-introducing species that have previously disappeared. Projects are still to be confirmed but are likely to include:

2008

2007

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