Are These Kites Headed for a Fall?
As U.S. Army Corps of Engineers projects shrink the habitat of snail kites
- Doreen Cubie
- Dec 01, 2006
As U.S. Army Corps of Engineers projects shrink the habitat of snail kites, the endangered Florida raptors also face the loss of their main food source
ANDREA BOWLING’S airboat shoots noisily across the top of white water lilies in Florida’s Lake Tohopekaliga. A startled alligator lunges at her boat, then sinks beneath the inky water. Bowling, a field technician with the U.S. Geological Survey’s Florida Cooperative Fish and Wildlife Research Unit, throttles back the engine until the big propeller slows to a stop. This flat-bottomed watercraft is a necessity in the shallow, vegetation-filled lake where she and her colleagues are studying snail kites, one of the most highly specialized raptors in the world.
“They are wetlands dependent,” explains Bowling, pointing out that these birds of prey feed almost exclusively in the United States on aquatic snails, especially the plump, brownish apple snails that are native to the Everglades and other Florida freshwater wetlands. Found throughout tropical America, Rostrhamus sociabilis lives in our country only in Florida. As that state’s marshes and sloughs have been diked, drained and destroyed over the last century, the U.S. birds—a distinct group once known as Everglades kites—have fared poorly.
The story of these kites is a complex one. It involves not just wetlands, which the birds must have to survive, but also the irrigation demands of Florida’s sugar industry and the health of Lake Okeechobee, one of the largest freshwater lakes in the country. This vast “liquid heart” of the state was once the kites’ U.S. stronghold. “The 100,000-acre marsh on the western side of the lake was very important to them,” explains Randy Sargent, wildlife conservation counsel for NWF.
But Lake Okeechobee is a highly manipulated body of water, controlled by the U.S. Army Corps of Engineers. In recent years, this federal agency decided to begin storing more water in the lake. “The Corps is keeping the levels high as extra insurance for sugar cane growers,” says Paul Parks, Lake Okeechobee project director for the Florida Wildlife Federation (FWF). Farmers want to have this water available for irrigation during times of drought, he says, but it comes with a steep price. “Deep water has drowned the marshes,” explains Parks. Most of the bulrushes and other aquatic vegetation have died. Not surprisingly, few snails remain and nearly all of the kites are gone. “It’s very simple,” adds Parks. “No snails, no kites.”
Today, many of the surviving kites have moved more than 100 miles to the north, to the much smaller Lake Tohopekaliga, on the outskirts of the city of Kissimmee, where Bowling is radio-tracking a young bird. Pulling out a pair of binoculars, she begins scanning and soon spots it hunting nearby, oblivious to the presence of people and airboats. Adult male kites are slate gray with red bills and a broad dark-and-white tail, but the females are a more subdued brown, and the juveniles, like this one, are a streaked tan and buff. Flying low on paddle-shaped wings, the bird hovers briefly and then drops straight down to the water. One foot slips beneath the surface and comes up with a plum-sized snail.
This species will sometimes capture a small turtle or other creature, but their slow flight, slender talons and sickle-shaped bills—which fit perfectly inside the shell of a snail—are adapted to catching and eating this one particular prey. In fact, an adult kite will eat as many as 50 apple snails a day. After plucking one from the water and settling onto a perch, a kite can use its sharp-tipped bill to extract the snail and devour it in less than 90 seconds. Unfortunately, being a dietary specialist can sometimes make life difficult.
The kites were first listed as endangered in 1967, when there may have been as few as 100 individuals in Florida. Over the intervening years, however, the population began to gradually increase, and by 1999, researchers tallied 3,577 kites in the Everglades, Lake Okeechobee area and the watersheds of the Kissimmee and Upper St. John’s Rivers. It looked like the beginning of an endangered species success story, but their numbers suddenly went into a free fall. By the summer of 2005, only about 1,300 could be found anywhere in the state.
In August 2005, NWF and FWF joined together to sue the Corps, contending the agency is mismanaging Lake Okeechobee and, in the process, harming the kites and violating the Endangered Species Act. While this case is waiting to be heard in the courts, scientists are continuing to study and count kites, but the future looks grim. “The birds are not fledging many young,” says Wiley Kitchens, a research ecologist and Bowling’s boss. Last year, only about 40 youngsters lived long enough to fly. No one is exactly certain why, but most signs point to extensive habitat loss, which makes it hard for the parents to find enough food.
“If snail kites are going to survive in Florida, the Lake Okeechobee marshes must be restored,” says Parks. For now, however, wind-whipped waves break over what remains of Okeechobee’s marsh grasses.
To the north, in Lake Tohopekaliga, Bowling watches as the young kite finishes eating its snail. The bird drops the empty shell and launches itself into the air to search for more prey. Bowling starts up her airboat and follows, as the kite—like the others of its kind—flies off into an uncertain future.
To learn more about NWF’s efforts to protect the nation’s wetlands and the species that depend on them, see www.nwf.org/water.
A New Generation
Like most birds of prey, a pair of snail kites works together to raise their young. First, the male woos the female with an elaborate sky dance, finishing up their courtship by capturing a snail and feeding it to his new mate. He builds the nest; she makes alterations. Both birds sit on the eggs and feed the chicks. Incubation takes 28 days, and it is another 28 days or so before the young make their first flight. But sometimes the mother bird refuses to wait that long: Scientists have observed female kites abandoning their nests before the chicks fledge, leaving the fathers to care for the young full-time while the mothers fly off to seek new mates.