Ocean Watch
By Susan Scott
Kailua couple sees birds
fight to the deathKailua reader Bill Kennon writes, "My wife and I witnessed a strange occurrence while hiking to the Lanikai pillbox. We often see frigatebirds soaring, but this is the first time we saw two in battle. For about five minutes, one bird seemed to attack the other in an amazing aerial display. Suddenly, one bird fell straight out of the sky, crashing to the ground from about 200 to 300 feet. I think its neck must have broken, since it was limp as it fell. Ana and I looked for the bird, but got bogged down in heavy brush. Have you ever witnessed such an event?"
Not only have I never witnessed such an event, I've never even heard of frigatebirds fighting. So I called Bob Pyle, the undisputed expert on Hawaii's birds. He never heard of it either. Neither did a bird specialist at the U.S. Fish and Wildlife Service.
But if any seabird might launch a deadly assault on another, it would be a frigatebird.
Frigatebirds are large, black birds, looking like pterodactyls as they soar effortlessly on currents high overhead.
It's easy to tell males from females: Males are all black. Females have white chests. Juveniles of both sexes have white heads and white chests.
Frigatebirds weigh only about three pounds, but have 7- to 8-foot wingspans. They also have a bad reputation as bandits. The birds' name comes from small ships called frigates, preferred by 16th century pirates. The bird's Hawaiian name, 'iwa, means thief.
Frigatebirds often hang around seabird nesting colonies looking for opportunities to snatch eggs and small chicks from nests. Most seabird parents, however, sit on their eggs and young chicks, giving frigatebirds few chances at kidnapping.
A more common source of food comes from the air. Frigatebirds attack boobies winging their way back to their nests at day's end to feed their chicks. In astonishing aerial feats, the frigate delivers pecks to the booby's neck, tail or wing. These pecks are not playful. The hooked beak of a frigatebird can break a booby's wing or leg.
Once from the deck of our sailboat, my husband, Craig, and I watched two frigatebirds fly toward a red-footed booby on its way to its nest. In unison, each frigatebird grabbed a leg of the booby, flipping the poor thing head over heels. During this aerial tumble, the booby regurgitated its fish.
The two thieves swooped for the falling fish, but just as one grabbed it, the other bird shot past, plucking it from the beak of the first. They did not fight over it. The winner simply flew off with the prize.
These aerial robberies are impressive sights, but the behavior is overstated. Frigatebirds also catch their own food, snatching up flying fish and squid, picking up stranded shoreline fish, and in some areas (not Hawaii), eating sea turtle hatchlings.
Frigatebirds don't usually gather in flocks, but people in Windward Oahu have reported seeing hundreds of frigatebirds pass by at one time. These birds are coming from (or going to) Moku Manu, a small island just off Mokapu Peninsula, where they roost at night.
One of the best things about hiking, sailing and snorkeling in Hawaii is knowing that a once-in-a-lifetime marine animal sighting is always possible. Watching two airborne frigatebirds fight to the death was one of those moments for Bill and Ana. I'm glad they shared it.
Marine science writer Susan Scott can be reached at http://www.susanscott.net.
