Observation of forest bird researcher Ralph Powlesland
Tui Nature Reserve, 7-8 February 2010.
Ralph Powlesland spent several years studying robin ecology at Kaikoura, South Island (1976-1979) and at Pureora, North Island (1996-1999). His studies included determining nesting success and adult mortality in relation to numbers of various introduced predators, particularly rats and stoats. He visited the Tui Nature Reserve during 7-8 February 2010 to see the reserve and discuss with Brian & Ellen Plaisier their management of it with regard to a possible future translocation of some robins to it. Of particular interest to Ralph was the diversity and maturity of the forest, availability of year-round water sources for forest birds, and the level of pest control (possums, stoats, cats and rats). All of these features in combination would be important for successful establishment of a robin population in the reserve.
Ralph was impressed with the maturity and stature of the forest given that much of the reserve has previously been cleared for pastural farming. Even though some of it is in the early stages of regeneration, there are reasonable areas of mature forest containing large matai, kohekohe, beech and mahoe trees. From the point of view of water sources for birds, at least two gullies have small streams that apparently contain water year round. Also Brian and Ellen are making good progress with establishing three ponds that will ensure water is readily available in other portions of the reserve.
Ralph noted that there was much evidence that good progress has already been made with reduction of introduced predator populations (possum, rat and stoat) to low numbers. Flower buds were developing on kohekohe, lots of kohekohe seedlings were evident (both flower buds and seedlings are sought-after foods of possums), untouched tawa fruit were available on the ground (usually these would have possum or rat gnaw marks on them), untouched toadstools were common (often damaged by possums and rats), and juveniles of a few forest bird species were seen (e.g. bellbird, fantail, grey warbler). Hopefully the monitoring of rat and stoat populations using tracking tunnels over the next 6 months or so will provide evidence that so few rats and stoats remain in the reserve that robins translocated there be very likely to survive and breed successfully.