Designing Safe Nest Boxes For Puaiohi

Field assistant Ruby Hammond works on a nest box. Photo courtesy Barbara Heindl

Rats are clever, but they haven’t been crafty enough to find their way into some of the latest nest box designs developed by Kaua’i Forest Bird Recovery Project in an effort to reintroduce the Puaiohi – an endangered native bird – into its former habitat.

“We actually found that rats are capable of amazing things,” says the organization’s field crew leader, Barbara Heindl, as she shows videos of the rodents climbing the metal poles of nest boxes and squeezing their way into awkward nooks and crannies. The footage was shot in an effort to find the best nest design that would not only attract the bird, but would keep predators at bay.

Rats have been known to eat the birds’ eggs, as well as the nesting females.

“If we can create nest boxes that are rat-proof, we can provide a safe haven and expand their range,” says Heindl regarding the Puaiohi, a small thrush.

Their original nest box design was a flower pot on a metal pole. With the enticement of peanut butter, however, rats were still finding their way into the devises, as evidenced by cameras snapping pictures each minute. They used their tails to balance and maneuver in remarkable ways and were able to chew through plastic without hesitation.

Barbara Heindl loves to work with Kauai’s native birds. Coco Zickos photo

“Everybody’s had experience with rats at some point,” says Heindl. “A lot of it is just getting people together and talking about it.”

Nest boxes have been used in the field for some 10 years, but this is the first time any evidence has been collected on predators.

While only one bird was recorded as having nested in the boxes prior to 2011, two Puaiohi utilized the boxes last year.

“So it kind of reopened this thought that maybe we can create something that’s rat-proof and attractive to Puaiohi,” says Heindl.

Helping the Puaiohi nest in areas other than along steep river drainages on cliff sides where its population has been forced to live, is important in its recovery as a species.

“Their range is really small; they’re almost entirely in the Alaka’i Plateau,” says Heindl. “We think that they’re restricted in range size because of nest site availability.”

The elusive birds were once abundant across the entire island, and their bones have been discovered at Makauwahi Cave Reserve.

“It’s thought that they’re restricted to the Alaka’i for several reasons,” she adds. “One is habitat destruction by people, and another is habitat destruction by pigs and goats.”

Another reason for their demise is avian malaria – passed on by non-native mosquitoes. The affliction is less prevalent at higher elevations.

“If we can get them to use these nest boxes, we can put them in areas where there aren’t nest sites, but they have food and other things available and we could potentially expand their range and their population,” says Heindl, who is responsible for conducting research on endangered species on-island.

The Puaiohi is the only remaining native fruit-eating bird on Kaua’i, and ensuring its survival is critical to the environment.

“It’s really unique and special because they play a big ecosystem service,” Heindl says. “If we can protect the Puaiohi, we can protect the native forest.”

This year, some 30 nest boxes have been placed around Koke’e. The nesting season begins toward the end of March, early April.

The hope is not only to replenish the population on Kaua’i, but to eventually use the nest boxes on Maui and the Big Island, particularly since native fruit-eating birds have already gone extinct on the other islands.

“If we lose the Puaiohi, we’re losing a huge tool as far as forest regeneration,” says Heindl. “I think it would be a real shame for a bird that’s as unique and special as the Puaiohi to really disappear, especially since they’re only found on Kaua’i.”