Most of the box traps were in place by the end of December. Baited with dehydrated rabbit meat, they have been placed every 200m along 120km of trap lines.
From spring, when predator activity picked up, the traps would be checked by Mr Varcoe either monthly or twice a month, Dr Hughes said.
"Russell has been terrific because he's a local who knows the area backwards and has the ideal mix of skills the trust was looking for.''
A baseline survey of the river delta's bird population, carried out by contractors for the trust last November, showed the four species classified by Doc as threatened lived in greater densities on the Dart River than on the Rees.
That was attributed to the Dart having a greater water flow than the Rees, and because it was a much larger river that provided better foraging and breeding habitat for the birds.
The Dart was also less infested with exotic weeds such as willows and lupins.
Dr Hughes said the project, which had come in on budget at $166,500, was funded by grants from the Central Lakes Trust, the Otago Community Trust, the Otago Regional Council, the Greenwood Environmental Trust and proceeds from a Real Journeys fundraising ball last August.
"Our challenge now is to develop a long-term funding stream to maintain the trapping.''
