A burgeoning population of kaka in Wellington is posing a threat to trees.
A biologist from Victoria University says the large native parrots dig into trees with their beaks to feed on the sap, eventually killing the trees.
Dr Wayne Linklater says the birds could become as much of a nuisance as kea are in parts of the South Island, but so far he has heard no complaints.
The Wellington City Council has teamed up with the university to see what can be done.
