One way to find Hawaiian petrel burrows is to sniff; the squid-eating seabirds emit a strong musk that lingers by their underground nests. Another way is to tilt an ear to the night sky and listen; petrels flying home after dark fill the air with musical yips and warbles. Their Hawaiian name, ‘ua‘u (ooh-AH-ooh), mimics these calls.
When Jay Penniman helped launch the Maui Nui Seabird Recovery Project in 2006, biologists knew little about Hawai‘i’s endemic pelagic birds, which spend most of their lives at sea and return to land only to nest. So Penniman and a small crew of biologists and volunteers conducted surveys, thrusting their arms shoulder-deep into burrows to capture disgruntled, smelly birds and affix leg bands.
Small though it is, the project has yielded huge discoveries. Penniman found a large, previously unknown colony of ‘ua‘u on Lāna‘i. He also helped outfit petrels with satellite transmitters. The data showed that when foraging for food for their chicks, ‘ua‘u fly as far as Alaska or Japan.
In addition to Hawaiian petrels, Penniman’s team monitors Newell’s shearwaters (‘a‘o) and wedge-tailed shearwaters (‘ua‘u kani). These birds were once so numerous their flocks were said to have darkened the sky. They nested from the sea to the summit, and their guano fertilized native forests. After the introduction of rats, mongooses and cats, ground-nesting seabirds nearly disappeared from the main Hawaiian Islands. The few remaining colonies exist on cliff-sides and mountain summits. “The biggest threat is habitat loss,” says Penniman. Between 1993 and 2013 the Newell’s shearwater population on Kaua‘i plummeted by 94 percent; Hawaiian petrels dropped 76 percent. Fortunately, Maui’s ‘ua‘u numbers increased during that period. Habitat management and predator control at the nesting site in Haleakalā National Park made the difference.
Penniman is working to fence and restore habitat at four additional nesting sites along Maui’s coast. “There’s a good deal of urgency for it,” he says. “With climate change and the rising seas, millions of birds stand to lose their breeding grounds. The most logical place for them to come is here, the high islands.” Thanks to Penniman’s team, when the birds arrive they’ll have a few safe spots to land.