A Bird in the Hand: Volunteers band shearwater seabirds
By Catherine Cluett Pactol
As dusk fell on the Mo`omomi coastline, silhouetted birds began to swoop over the shore and across the grasses and native plants of the dunes. Donning their headlamps, a dozen biologists, conservationists and volunteers stood by, waiting for the birds to settle. Then, in the pitch blackness and gusty wind, the group broke into small teams and vanished into the darkness.
Brandishing their flashlights and tools, the teams searched the ground for piles of sand and holes that would indicate a burrow. The inhabitants of the holes are Wedge-tailed Shearwater, or `Ua`u kani, an indigenous seabird with gray-brown and white feathers, a long, hooked beak and a wingspan of more than three feet. Clumsy on land, the birds live most of their lives on the wing at sea, and come onshore only to breed. These burrows could contain a single bird in search of its mate, or a pair, resting for the night.
The task of the volunteers — who ventured out as part of an annual effort last month — seemed fairly straightforward. Capture the birds, place a small, metal band on one leg, then release them back to their burrow. By logging data on the bands and keeping track of recaptures, experts hope to be able to learn more about the demographics of the bird population, breeding habits and where colonies are thriving.
“Mo`omomi is a very significant colony for the state — it’s among the largest populations,” said Jay Penniman, project manager of the Maui Nui Seabird Recovery Project. “It’s a shining example of what you can do by just changing the habitat and removing predators – it’s a jewel.”
Penniman was referring to the efforts of The Nature Conservancy (TNC) Molokai, along with partners like the Molokai Land Trust. They cleared kiawe from the area, restoring the habitat for native plants and shorebirds, and fenced it off from predators like cats and dogs that prey on the adults and chicks, as well as deer that stomp and collapse the birds’ burrows, said Penniman. The banding efforts began in Maui County in 2000, when biologist Fern Duvall set out to track whether the bird populations in certain locations were increasing or failing.
While the mission of volunteers last month might seem simple, catching and banding the birds is actually no small task. Volunteers lay on the ground to reach down the burrows, sometimes longer than an outstretched arm. They wore gloves to prevent bites from the birds’ powerful beaks, disgruntled from their unwelcome extraction. One volunteer secured the bird on its side, while the other — carefully trained in the art of banding — used special pliers to delicately clamp a metal ring around the bird’s left leg. A third volunteer recorded data from the band into a database. Some birds were already banded, so instead of logging new data, they would be recorded as a recapture.
Over a three-hour period, volunteers logged 233 newly banded birds and 66 recaptures this year — results that Penniman said are similar to previous years. While that represents only a portion of the shearwater population breeding at Mo`omomi — believed to be about 3200 adults — it is a good sample, he said.
`Ua`u kani are largely monogamous, taking one breeding partner during their 35 to 40-year lifespan. They normally come back to breed in the same location they hatched as a chick. This is one of the aspects that biologists are using the bands to study: some birds will start new nesting areas, which is how Mo`omomi originally got started as a recent nesting area after 2000, when TNC began its clearing efforts, said Penniman.
“[Through the banding] we’ll be able to see if the chicks banded in a colony return to that colony or showed up in other colonies,” he said.
After mating, the male and female birds go back out to sea and the female will come back to the burrow in early June to lay a single egg. With 18 percent of her body weight lost in the egg, the female immediately goes back out to feed, while the male takes the first turn incubating the egg, said Penniman. About two weeks later, she comes back and they trade off while he eats. After 52 days, the chick hatches and the adults take turns for a day or two at a time feeding and staying with the chick. After a week, the parents leave the chick by itself for up to a week at a time while they forage at sea and bring food back for their young. Penniman said GPS tracking shows that adults will travel up to 250 miles out to sea during this time.
“There’s only one egg, and if they lose that egg, they’re done for the year,” he said of the parents. “And if one adult dies, that chick is dead. It takes both parents [to raise it].”
The chicks stay in the burrow for 120 days, and when they leave they’re fully feathered and ready for a life at sea. They won’t return to land for five to six years until they’re ready to breed themselves.
Though the birds occasionally land on the water, Penniman said the majority of their lives are on the wing — even when they sleep.
“When they fly, they’re capable of shutting down half their brain to sleep – they go on autopilot,” he said. “`Ua`u kani dive for their food and actually fly under water chasing down their prey.”
Volunteers will return in the fall to band the chicks as well. For the biologists and volunteers, it’s all worth it.
A young volunteer said at the beginning of the evening that her goal was to capture one bird.
“I grabbed 13 birds!” she said proudly at the end of the night.
Another volunteer said what drives her to walk through the dark and stick her arm down dark holes for biting birds is an effort to keep animals off the endangered list.
“I once read that long ago, the Hawaiian petrel [a relative of the shearwater and now an endangered species] used to ‘darken the sky on Molokai,'” said Diane Pike. “That thought has never left me. I feel that it is not only my passion but my duty to help in any way I can to prevent more plants, birds or other animals from going extinct.”
“One of our primary goals is to reestablish seabird species on all islands – this family of birds is 70 million years old,” said Penniman. “Mo`omomi clearly shows that if you provide habitat and protection, you’ll see an increase in population – that’s a success.”