An influx of starving native pigeons at a Northland bird hospital is likely due to the combined effects of a bad year for a particular species of tree and a rat plague chomping through the birds' usual food, an expert says.

Robert Webb, of Whangārei's Bird Recovery Centre, said most years he treated about 80 kūkupa, also called kererū or wood pigeons, for a variety of ailments but this year had been particularly bad.

Last month more than 25 kūkupa had been delivered to the Whangārei centre while another 10 had been found ailing in Kerikeri. Some of the birds were literally starving, Webb said.

Forest and Bird's Northland advocate, Dean Baigent-Mercer, believed the high number of hungry kūkupa this year was due to a disruption in the birds' seasonal food calendar this winter because taraire trees hadn't fruited much during winter.

Forest and Bird Northland advocate Dean Baigent-Mercer. Photo / Dean Wright
Forest and Bird Northland advocate Dean Baigent-Mercer. Photo / Dean Wright

''Taraire are the powerhouse of northern forest kererū populations and with their big purple fruits used to feed flocks of thousands of kererū," he said.

In areas with good pest control, however, kūkupa were doing fine because they were feeding on the berries of porokaiwhiri/pigeonwood and other trees that produced berries at the end of winter and the start of spring.

"In areas where pest control doesn't target rats, the high numbers of rats have scoffed the berries meant for kererū which means the birds miss out," Baigent-Mercer said.

Webb suggested leaving out corn for the hungry birds but Baigent-Mercer also suggested planting kōwhai trees as a longer-term fix.

Anytime there was a food shortage kūkupa could eat kōwhai leaves until berries were ready.

However, the best thing Northlanders could do was to carry out pest control targeting rats, possums, stoats, ferrets and feral cats.

"Introduced rats and possums scoff the berries kererū eat, feral cats, ferrets, and stoats kill adult kererū, and all of these pests target kererū chicks and eggs. Survival is tough for these birds we love, but effectively controlling all the pests means we can bring back massive kererū flocks like there used to be,'' he said.

■ If you find a kūkupa in distress you can take it to the Bird Recovery Centre, behind Kiwi North in Maunu, or call (09) 438 1457.