Orokonui Ecosanctuary Stoats probably eradicated.

“The Orokonui Ecosanctuary is most likely to be free of stoats after a year long battle” says Conservation Manager, Elton Smith. Last week an intense four day walk by a specialist stoat detection dog came back empty handed and this result, along with results from other monitoring tools, means stoats are at undetectable levels. It would appear the last Orokonui stoat was killed in a den site in the middle of the sanctuary in early November which means that stoats could have been residing in the sanctuary for up to 10 months.

The presence of stoats for this long has come at a high cost. Saddleback, the most sensitive of bird species to mammal predation, is now thought to be extinct within the reserve. Stoat predation would have caused a significant loss to the population of 40 -50 birds. In addition the cost of contractor dog work was around $8,000 and new traps and technology another $2,000.

Staff, volunteers and associates put in the most intensive effort ever carried out in pursuit of a stoat in a mainland sanctuary. Mr. Smith alone spent around 60% of his time in 2015 on the stoat battle.

DNA analysis would strongly indicate that Orokonui probably had 2 separate stoat incursions last year, Mr Smith explains. The two stoats caught in January 2015 were siblings, whilst the female trapped in November was completely unrelated.

How the stoats gained access into the sanctuary is still not 100% known although there is reason to believe that one incursion was through water gates that open at high flow times and the other possibly occurred in June when a severe snow storm compromised much of the fence’s mammal-proof integrity with frozen snow on the fence hood.

“We learnt a couple of harsh lessons last year”, said Mr Smith. “Our water gate system can be a major weakness and this needs a permanent engineering solution and better staff response to problems. We also now know that we must be out in winter storms to attempt to remove snow as it accumulates – an interesting proposition”.

The true front line of Orokonui – the external trap line – is being upgraded to better target stoats and the prospect of a large trapping programme as part of the Orokonui halo project ‘Beyond Orokonui’ should take a lot of pressure off the fence.

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