Banding Hummingbirds to Solve their Mysterious Ways
People from all walks of life jump at the chance to hold these creatures.
Ned and Gigi Batchelder belong to the community of enthusiasts who study western hummingbirds. Like the Sargents, they have upended their lives to do hummingbird research. Five years ago the Batchelders--who were employed for 25 years in the energy industry--moved from Oklahoma to Montana, where they work winters at local jobs in order to spend all summer banding calliope, rufous, broad-tailed, and black-chinned hummingbirds.
Since the spring of 2001 the Batchelders have banded 6,000 hummers. The majority were rufouses and calliopes; the latter, just over three inches long, are the smallest long-distance avian migrants in the world. Every year calliopes tackle a perilous 5,000-mile round-trip migration, from the mountains of the western United States and Canada to south-central Mexico and back again. In 2003 the Batchelders recaptured 228 birds they had originally banded in the previous two years. The birds' "anklets" revealed a remarkable fact: After navigating across two countries, most of the banded hummers returned, almost to the day, to the exact gardens and yards where they had summered the year before.
The reason, says Jesse Grantham, former director of bird conservation for Texas Audubon, who is now working with the U.S. Fish and Wildlife Service to restore California condors, is that "hummers are trying to stick to a 10,000-year-old strategy of being at a certain place at a certain time, because that's when factors are ideal in those particular locations. The problem is that the habitat during this time period has totally changed."
Hummingbird festivals, such as the one Grantham started in 1988 in Rockport, Texas, and the annual celebration he started in 1999 at the Strawberry Plains Audubon Center, are timed to take advantage of this predictable peak migration. "Sometimes it takes a spectacle to get people excited about birds," says Madge Lindsay, the center's executive director (and the executive director of Mississippi Audubon), who doubled the festival's attendance by first inviting the banders there in 2002. "We have so many hummers migrating through--a river of birds from Canada to the Gulf Coast--that the sky is thick with them. It's pretty spectacular."
Calliope, Allen's, Costa's, Lucifer, buff-bellied, and rufous hummingbirds have all been named to the Audubon WatchList of at-risk species. Most have been singled out because small breeding and winter ranges increase their vulnerability to potential disease outbreaks, natural disasters, and habitat destruction. The rufous hummingbird, however, is of particular concern. Some of these hummers travel about 6,000 miles round-trip between the forests of central Mexico and coastal Alaska each year--measured in body lengths, it's the longest migration of any bird in North America. According to the Breeding Bird Survey, conducted annually by the U.S. Geological Survey and the Canadian Wildlife Service, from 1966 to 2002 the species has experienced a decline of 2.7 percent per year across its range.
To refuel for extended migrations, hummingbirds require stopovers in reliably nectar-rich habitat. But these areas are disappearing, not just in Mexico and Central America but throughout the United States. "As the birds move south, their habitat becomes more and more degraded. They waste a lot of time looking in flowers that aren't going to provide them with any reward in food or calories," says Grantham. Prime habitat all along their migration routes is being chewed up by everything from suburban sprawl and pesticides to invasive species and chip mills.
While banding may track the physical condition of hummers and how they are being affected by this habitat loss, homeowners needn't wait for data to prove they should take an active role in protecting them. "The average person can't really do anything to help peregrine falcons or mountain plovers, but they can do something for hummingbirds," says Sheri Williamson, author of A Field Guide to Hummingbirds of North America, who bands hummers with her husband, Tom Wood, at a station along Arizona's San Pedro River. "We underestimate the role yards and gardens have played in migration corridors," she says. A yard full of trumpet creeper and salvia and other hummingbird plants is not going to replace lost breeding areas, "but it may be able to reduce the impact of habitat destruction along migration routes."
Flowering gardens are vital, especially to ruby-throats, some of which make a nonstop, 18-hour, 500-mile-plus flight across the Gulf of Mexico. In order to complete this arduous journey, they must put on layers of fat, which their bodies burn for fuel as they fly. By hanging around a lush yard--free of pesticides, since insects can make up more than half of a hummer's diet--migrating ruby-throats gain grams in no time at all. One young female, for example, weighed 3.06 grams when Bob Sargent first trapped and banded her in mid-September at his Alabama home. Five days later, when he caught her again, she weighed a hefty 5.31 grams--well on her way to doubling her weight.
Providing sugar-water feeders could also be critical to the birds' survival, says Grantham. "We look at them as entertainment, but to hummingbirds, it may be a life-and-death struggle." Hummers are naturally solitary animals, he says, so seeing them piled up at a feeder, chasing and fighting one another, is a sign that they may really need the food.