Top of the South Island News- Summer 08


Top of the South field trip to Lake Rotoiti

Twelve members of the TOS Branch attended a field day at the Rotoiti Nature Recovery Project “mainland island” site at Lake Rotoiti on November 12, hosted by a Department of Conservation team led by Dave Rees. The objective was to update everyone on current animal control practices and to look at the achievements of the decade-long programme.
Top of the South field trip to Lake Rotoiti

Twelve members of the TOS Branch attended a field day at the Rotoiti Nature Recovery Project “mainland island” site at Lake Rotoiti on November 12, hosted by a Department of Conservation team led by Dave Rees. The objective was to update everyone on current animal control practices and to look at the achievements of the decade-long programme.
The morning presentation on current practices and achievement generated a lot of debate. The techniques for maintaining mustelids and possums at very low densities are effective but there are major challenges in managing rats, mice and feral cats. There is a proven technique for poisoning wasps but problems with the availability of an ideal toxin. Intensive monitoring has provided some excellent long-term data, assisting with the development of best management practices. The sensitivity of the different monitoring methods using tracking tunnels generated a lot of discussion.
The response in bird numbers has been variable, and comparison between the mainland island with intensive control of a range of predators, the head of Lake Rotoiti where stoat control is undertaken, and Lake Rotoroa where no stoat control takes place, has provided a much better understanding of predator/prey relationships.
There was a lot of interest in the survival and breeding of the great spotted kiwi with seven pairs translocated from the Gouland Downs area in Kahurangi National Park. Since 2004 four chicks have been born and survived to become adults. Unfortunately, the mother of one was drowned crossing a fast-flowing stream. The young kiwi chicks stay with their parents for over a year, reducing the risk of stoat predation but it means that the adults only nest every second year. With only three females laying, the gene pool is very limited. Planning is under way to see if the low productivity rates can be increased by introducing 10 to 14 kiwi chicks hatched from eggs taken from the Gouland Downs. This will increase the number of breeding kiwi in the site. The fitting of transmitters to the kiwi has provided opportunities for daily monitoring to determine nesting attempts, location and health.
The afternoon started with a boat trip along Lake Rotoiti and the group walked back through the mainland island area. The day provided an excellent opportunity for an exchange of ideas between members from different agencies, an appreciation of what has been achieved by DOC at St Arnaud over the past decade, the realisation that any significant reduction in predator control could lead to a rapid and dramatic loss of biodiversity, and the need for ongoing development of better tools.

Lindsay Vaughan
Branch Chair
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Field trip participants set off by boat for the top of Lake Rotoiti.

Beech strawberry fungus on silver beech (Cyttaria gunnii).

One of the new cat traps in use.

Field trip participants in the bush beside Lake Rotoiti.