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Stoats Threaten Yellowheads

Research by Department of Conservation scientists shows that stoat control could hold the secret of survival for the native yellowhead.

Once found in large flocks throughout the South Island, the yellowhead now has sizeable populations only in the Fiordland and Mt Aspiring National Parks. Forest clearance, predation by introduced mammals, and competition with wasps are thought to be responsible for the decline.

The hole-nesting forest bird is vulnerable to the stoat population eruptions that follow heavy beech-seeding seasons, says DOC scientist Colin O'Donnell. Eighty per cent of yellowhead nests in a trapped area fledged young, compared to only 36% in an untrapped area. Fewer breeding females disappeared from the trapped area, and breeding pairs produced nearly twice as many young from fewer nests.

"The difference in breeding success between these two areas reveals that reducing stoat numbers by trapping should significantly increase the yellowhead's suvival chances," says O'Donnell. "This shows that further development of stoat control techniques is warranted."

Catherine Gilmour, DOC