Magnificent Frigatebirds love the north end of Bird Island.
Adult males, females and white-headed juveniles were there in large numbers last Wednesday evening when my husband, daughter and I boated out to the island.
Fregata magnificens is the largest species of the five-member frigatebird family. Frigatebirds are found world-wide gliding above the warmer oceans.
Males are all-black with a scarlet throat pouch that is inflated like a balloon in the breeding season. Although the feathers are black, the scapular feathers produce a purple iridescence when they reflect sunlight, in contrast to the male great frigatebird’s green sheen. Females are black, but have a white breast and lower neck sides, a brown band on the wings, and a blue eye-ring that is diagnostic of the female of the species. Immature birds have a white head and underparts.
When I first saw the frigatebirds on Bird Island, I thought they might be nesting like the other birds on that special mangrove island right next to our little peninsular town in the southern Treasure Coast. But there is only one confirmed nesting location for these birds in Florida.
From an article in the Orlando Sentinel, Magnificent frigatebird may face bleak future…
Florida has a small population of frigate birds that nests each year; their home is a group of islands at the end of the Florida Keys called the Dry Tortugas.
Thousands more breed in South America or on Caribbean islands and come to South Florida for the winter.
And summer, I would say.
That so many of the birds visit Florida suggests to (Florida expert Ken) Meyer that the state has enough habitat to support a second population of nesting frigate birds.
He thinks an ideal site would be among remote islands of the Florida Keys that are uninhabited and protected as sanctuaries.
Beginning last year on those islands, Meyer and staff of the U.S. Fish and Wildlife Service have been setting up frigate bird decoys and speakers that play recordings of the birds.
Customized with paint and plywood, the decoys are made from manufactured decoys of other birds.
Meyer said the decoys aren’t “fine art” but they work well, presented in a half-dozen postures.
“It’s really cool to watch; the birds come in and snuggle up next to a decoy,” he said. “It’s not like they ever catch on.”
Frigate birds do not breed until they are 5 to 10 years old, which means the efforts to lure the birds must be repeated for many years, Meyer said.
Interesting! Maybe frigatebirds could start nesting on Bird Island too. These look mostly like males.
Prior to each nesting season, adult males congregate at nesting locations in what is known as a lek, in an effort to attract females to the nesting site. As the nesting period draws nearer, the males will compete for their mates through an elaborate display. While female frigatebirds are soaring over the lek, the males will display from the top of the mangrove canopy by inflating their bright red throat pouch, roughly to the size of a volleyball, and flail their wings, all while tilting their bill towards the sky and calling out to the females above. Females use this display to select their mate, and will begin nest building soon after. Fledgling frigatebirds will stay in the care of their mother for six to nine months after hatching.
While thousands of non-breeding magnificent frigatebirds can be found across the coastlines of Florida and the Caribbean during many months of the year, there is now only one known breeding frigatebird colony in North America. Historic accounts have documented breeding activities within the Key West National Wildlife Refuge on Marquesas Key from the 1960’s through the late 1980’s, when the nesting colony was abandoned. These birds were thought to have left their colony due to human disturbance, and were soon after observed nesting within Dry Tortugas National Park, 45 miles west of Marquesas Keys.
Current efforts are in place to re-establish nesting frigatebirds within select islands of Key West National Wildlife Refuge through a social attraction and monitoring study. Refuge staff members and volunteers have partnered with Avian Research and Conservation Institute personnel to place fleets of frigatebird decoys within the mangrove canopy of each study site, mimicking the stages of pre-breeding and breeding behaviors. Each artificial colony has the added realism of audio from recorded frigatebird calls projected through a broadcast caller.
More fascinating frigatebird facts from NPR: Nonstop Flight: The Frigatebird Can Soar For Weeks Without Stopping…
Frigatebirds, seagoing fliers with a 6-foot wingspan, can stay aloft for weeks at a time, a new study has found. The results paint an astonishing picture of the bird’s life, much of which is spent soaring inside the clouds.
“It’s the only bird that is known to intentionally enter into a cloud,” Weimerskirch says. And not just any cloud — a fluffy, white cumulus cloud. Over the ocean, these clouds tend to form in places where warm air rises from the sea surface. The birds hitch a ride on the updraft, all the way up to the top of the cloud.
Frigatebirds have to find ways to stay aloft because they can’t land on the water. Since their feathers aren’t waterproof, the birds would drown in short order. They feed by harassing other birds in flight until they regurgitate whatever fish they’ve eaten and the frigatebird takes it. Or they fly over a fish-feeding frenzy on the ocean surface and scoop up small fish that leap out of the water to escape larger fish.
So in between meals, apparently, frigatebirds soar … and soar … and soar.
In one case, for two months — continuously aloft.
(That one seems to be molting.)
New respect for these strange birds. It’s pretty special we get to see so many at rest in one place.
One of the tagged birds soared 40 miles without a wing-flap. Several covered more than 300 miles a day on average, and flew continuously for weeks. They are blessed with an unusual body. No bird has a higher ratio of wing surface area compared with body weight — something called “wing loading.”
Writing in the journal Science, the researchers discovered that frigatebirds have also capitalized on a lucky coincidence. Winds that form these updrafts in the atmosphere also disrupt waves at the sea surface.
“We found that there’s a remarkably good correspondence between those two things,” Deutsch says. And when the regularity of waves is disrupted, deeper water rises to the surface, carrying with it things such as phytoplankton that attract small fish. The small fish attract bigger fish, which creates the feeding frenzy that frigatebirds need to dine.
So it seems the life of a frigatebird is simply hopping off at the bottom of this atmospheric roller coaster, eating and getting back on again to search for the next meal.
A cormorant and a pelican among the frigatebirds.
It was neat to watch them take off by just opening their huge wings and lifting up with the wind.
We’ve had some wind lately, when Hurricane Gordon traveled north through the Gulf of Mexico on the other side of Florida. I wonder if these birds came in on the east winds and are taking a break on this sanctuary island.
Bills of the cormorant and frigatebird are similar. The two species are related, both members of the Suliformes order.
Seven-foot wingspan on display.
A magnificent spot.