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NORTH ISLAND ROBIN UPDATE

 

Improved pest management has made for a bumper breeding season for the robins at Little Windy Hill. At time of writing 23 young had been banded and fledged. This compares very favourably with the 16 young fledged in 2005-6 and 13 in 2004-5 from the same number of pairs. There are still 2 pairs sitting on 4 eggs so the final total of fledged juveniles may be as high as 27. This season began with five breeding pair of birds made up of the robins translocated from Tiritiri Matangi in 2004 and locally bred birds. However, after the first nesting round two birds from separate pairs disappeared leaving just four pairs for the remainder of the season. It is not known if they were predated by moreporks, hawks or died of old age. The two Ďsinglesí then paired up, relocated their territory, and went on to successfully nest. It takes intensive effort to have the nests protected from rat predation. Throughout the robins territories rat traps and poison baits are spaced every 25x75m and this year a buffer zone of 150m of baits on one side of their area helped reduce rat invasion from unmanaged land. Out of 16 nests only one has been predated by rats.

Glenfern Sanctuary had an increase in birds with 7 nesting pairs from 5 pairs last season. The loose male in Kotuku mated with a juvenile female fledged last year. Another pair, that hadnít been seen since the month of the release in April 20005, were found above the Karaka Bay Rd after the protected area boundary had been shifted to there and their nesting attempts monitored.

Despite the increase the nesting success was more variable with moreporks, possibly hawks, and a rat preying on chicks. From seven pairs eleven young fledged with 11 chicks lost. Two nests were lost to wind and several abandoned which is quite a common occurrence with these birds. One was abandoned at Windy Hill.

Robin young are chased out of the parentís territorial area after they have fledged and some may return the following breeding season to re-establish pairs. They disperse quite widely with three robins having been spotted up on Mt Hobson recently. One of these has come from Windy Hill, one is unbanded, and the third has yet to be identified.

One value of intensely monitoring one species is that it acts as in indicator of likely breeding success for other birds within the area managed for rats and feral cats. Based on the success of the robins at Windy Hill it is probable that other birds have had a very productive year with much reduced predation. Confirming this, six young kaka were spotted in two nests early in the season within the managed area. One of reasons that small birds survive here at all, in spite of the onslaught from rats, is that they are such prolific breeders and start their breeding in late August/September while rats are still at reduced winter numbers. Most predation seems to occur with the rise in rats from January on when small birds may be on their third or even forth nest.

If you spot a robin please try and identify it by reading the coloured bands on its legs from left top down and then right top down, just as you would read a book. Call Tony on 091 or Judy on 306 to confirm where the birds came from.

To avoid a genetic bottleneck from breeding from such a small number of birds, Glenfern Sanctuary and the Windy Hill Rosalie Bay Catchment Trust will look into a booster translocation of robins from a different source in 2008.