Nature Notes (copy)

A magnificent frigatebird soars through the sky. This bird species can have a 7-foot wingspan and can travel vast distances by using thermals and air currents.

Editor's note: This story has been changed from its original post to correct the author.

Have you ever seen a large black bird with a forked tail that looks prehistoric soaring above the beach? Those are magnificent frigatebirds, and they are indeed magnificent. They are a long-winged bird of tropical oceans that makes their way to the Texas coast during their non-breeding season, which oddly enough corresponds to our summer.

The females and young males have white chests and adult males have red gular patches or air sacs which shows up quite prominently in flight. The males inflate these air sacs as part of the breeding display to attract females. The birds we see here in Texas are the products of post-breeding dispersal and are birds that are wandering in search of food. It is unusual to find an adult male in Texas, so if you see one with a red throat patch, consider yourself lucky.

They are rarely if ever seen sitting on the water since their feathers are not waterproof, but they frequently will sit on posts in our bays during the summer. They catch most of their food by snatching fish or squid from near the water’s surface, but they also have a reputation of being pirates because they will chase and harass other birds until the chased bird regurgitates a recently caught meal, at which point the frigatebird will dart down and catch the food before it hits the water.

The only place in the U.S. where this species breeds is the Dry Tortugas off Florida, but they nest widely in the Caribbean and along the Pacific coast of Mexico. They nest in colonies and their nests are on the flat tops of low bushes or trees, most often in mangroves, and are usually no more than a few meters above ground.

Once a female has chosen her mate, the pair begins nest building. The male collects and brings sticks and the female arranges them. Interestingly, studies have shown that nests are always located so these large birds can fly into the wind to land on their rather small and fragile nests without damaging them. They lay only one egg, and the breeding period is exceptionally long, with young fledglings often still being fed by the female when they are a year old. Researchers hypothesize that males leave their mate and young chick in time to molt and participate in breeding each year while the females breed only every two years because of the long chick-rearing period.

This bird is in decline primarily due to loss of breeding habitat. Human disturbance and introduced predators have extirpated many historic colonies. If you want to see large numbers of frigatebirds in Texas consider making a visit to Gulf Coast Bird Observatory’s Hawk Watch at Smith Point on the eastern side of Galveston Bay. Our hawk watcher, Bob Baez, has experienced some great frigatebird numbers throughout the seasons. The frigatebirds can sometime make up for the lack of raptors on a slow day.

Susan Heath, Ph.D., is an avian conservation biologist for the Gulf Coast Bird Observatory, 299 Highway 332 W. in Lake Jackson. Contact the observatory at 979-480-0999 or visit gcbo.org.

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