Extending the trapping programme will save precious lives

Date: 01 February 2008

A trapping programme protecting the endangered takahē in Fiordland's Murchison Mountains is about to be extended after its benefits were highlighted during a beech mast season that saw stoat numbers explode.

The extended trapping programme, to be rolled out over two years, will include the entire area of the Murchison Mountains Special Area, about 50,000 hectares, and cost about $205,000 to set up and $65,000 annually to run. Presently a third of the area is covered.

The Department of Conservation is confident the increased trapping programme will prove its worth not just for takahē but for a range of species such as the kiwi and whio/blue duck who are vulnerable to stoat predation.

Moves to increase the trapping range came after recent takahē population census counts showed stoats were affecting survival levels, the first time this had happened since monitoring of the population began 50 years ago. Only a few stoat predation incidents on adult takahē have been recorded in the past.

The counts showed an increase of takahē in the trapped area - an initiative set up in 2002 to test the effectiveness of trapping for takahē, but a decline outside the trapped area.

"In the past, most takahē deaths have been from cold winters and food availability," said Reg Kemper DOC, Area Manger in Te Anau "but what our monitoring is telling us is that stoats can and do kill adult takahē, and this is most upsetting."

The impact of stoats in the Murchison Mountains Special Area has caused a 25 per cent decline on the total takahē population, now estimated to be 225.

Mr Kemper said despite the stoat plague, a 2 per cent increase in the trapped area was recorded, proving that trapping is an effective tool and the increased protection will assist in the recovery of this loss.

"The great work of the takahē recovery team, those at the Burwood Bush Rearing Unit , and the support from Mitre 10, has put the species in a position to sustain, and successfully recover from this stoat assault.

Mitre 10's support has been integral to the success of the trapping programme and notwithstanding this event, Mitre 10 has confirmed its involvement is for the long term.

"I dread to think how this could have turned out if a mast year event of the same magnitude happened 10 years ago when takahē numbers were considerably lower," Mr Kemper said.

ENDS

Background

By 1898 takahē were officially thought to be extinct but a number of birds were rediscovered in 1948 in the Murchison Mountains. Shortly afterwards this range was set aside as a Specially Protected Area for management of takahē. Annual census throughout the 1960's revealed that the population was in decline and, by 1971 it had become clear that takahē were heading for certain extinction.

Active management began in the 1980's with the development of a captive rearing programme and sustained deer control. In addition to this a number of islands were seeded with takahē to act as insurance for the population. These management techniques turned the tide on takahē decline and by 2006 the total population had increased to just under 300 individuals.

In 2002 a stoat control programme was setup with the aim of determining whether stoats were impacting on the rate of takahē recovery. Preliminary results showed that stoats were having an effect on takahē survival but it wasn't until the 2006/07 season that it became clear how significant this was. At this time stoat and rat numbers escalated following a beech mast.

Additional information

• The extended trapping programme will be in place by next season.
• The heavy beech flowering the previous spring and the subsequent heavy seed drop (beech mast) led to a huge increase in the number of rats which meant increased food for stoats and an increase in stoat numbers.
• More than 1200 stoats have been killed in the trapped area since its inception, including last winter's tally of 250 which resulted from the beech mast year.
• The Murchison Mountains trapping is part of a pest control programme undertaken by DOC and community groups that includes significant areas between Milford Sound and the Kepler Mountains. This programme provides benefits to a range of species, not just takahē.
• The trapped area saw takahē numbers increase from 45 birds to 46. Any increase during a beech mast year is phenomenal achievement.
• The stoat numbers stayed high through the winter (possibly due to it being too mild to knock them back and enough food available to sustain them than would usually be the case). They have tailed off now and other food is available for them so they are not desperate enough to take on 2kg adult birds.
• While takahē can kill stoats in their powerful beaks, it appears that when stoat numbers are very high, the likelihood of a stoat encountering an unaware takahē, like one sleeping at night, increases. In this situation it is easier for a stoat to make a kill.
• Takahē have withstood previous beech mast years and while some losses have been sustained, nothing like what has been experienced during this beech mast.
• The following graph shows the trend in the wild takahe population over the past 25 years. The years following beech mast periods have been highlighted. Note that while there have been population dips following beech masting these have never been of this magnitude. In addition they have typically been accompanied by other factors such as very cold weather and limited food availability that the losses have also been attributed to.

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