The beautiful sound of tūī flocking to kōwhai trees beside Wellington harbour is becoming an annual occurrence with a local resident attributing it to the large number of predator traps in the area.

Eastbourne resident and conservationist Sally Bain has spotted the tūī in York Bay each September for the past three years.

They are usually seen in the biggest numbers when kōwhai come into flower. Last week Bain spotted dozens in the tree and above her head.

"Now you can just stand outside and hear them all over the bay. They may not be flocking around the bay in that sense that I saw them that week, but they are there. You can definitely hear them. They are astounding."

A tui after its favourite dish - kowhai nectar. Photo / Mark Mitchell
A tui after its favourite dish - kowhai nectar. Photo / Mark Mitchell

Bain said the number of birds migrating to the bay was growing each year. There had been a large trapping effort happening in the forest park behind the bay and she was also leading an urban trapping scheme called ERAT, Educating Residents About Trapping, for residents where one person was responsible for checking the traps for each street.

"I think it's a result of long-term trapping efforts and poison as well."

"In the last year the bird life has just exploded around the bay. It's worth visiting and just hearing it. You drive up the road, turn the car off and wind your windows down and it's just amazing."

Residents had also noticed a huge increase in the number of insects in the garden and there were also a large number of kererū around too.

"There's one almost every 50m or so. Walking around the road you always spot them."