At 6:30 on a Wednesday morning, the early August sun creeps over a rocky ridge at Mesa Verde National Park in southwestern Colorado. Dense stands of Gambel oak, Utah serviceberry and rabbitbrush spring up from the grassy meadows around Morefield Campground. Birdsong and the whir of hummingbird wings mingle with human whispers in the chilly dawn air. Steve Somora, a retired electrical contractor, peers through the pale light at a hummingbird feeder, which hangs from a frame about 50 feet away. The frame supports a Hall trap, a cylindrical mesh curtain that can be raised and lowered from a distance. As Somora watches, a hummingbird hovers near the trap, then ventures below it, alighting on the feeder's rim. When the tiny creature lowers its head to sip the sugar water, Somora releases the trap, which drops to cover the feeder and the startled bird. He slides his hand inside the mesh and reaches for the bird, holding it gently in his hand; its little head sticks out between his first two fingers. Carefully placing it in a net bag, he carries it over to a picnic table, where it will be identified, measured and banded before it is released.

Like his six fellow volunteers, Somora got up hours before dawn to drive to Mesa Verde. They're all part of the Hummingbird Monitoring Network (HMN), a nonprofit organization dedicated to hummingbird conservation. Most of them have been doing this twice a month, May through September, for four years; 2011 marks the fifth year of monitoring at Mesa Verde. Their enthusiasm is palpable, their eyes as bright as the sheen on a hummingbird's feathers.

Lynn Udick, a research database designer, sits at the picnic table wearing a magnifying headlamp, with a hummingbird identification manual within reach and an array of small tools and supplies spread out before her, including those staples of volunteer gatherings everywhere, coffee and banana bread. She is the designated bander. Jane Pedersen, a semi-retired psychotherapist (and wife of Steve Somora) records the information on datasheets; another volunteer enters the data into a computer. Yet another sits next to Udick, ready to feed the hummingbird sugar water before it is released.

What brought this disparate group together at Mesa Verde, and at the many other sites maintained by the network, is a love for hummingbirds, those amazingly agile, brilliantly colored, blurred-winged little creatures that enliven our gardens every year, aggressively protecting their flowers -- and feeders -- and sometimes migrating thousands of miles to breed. The landscape of the West is changing rapidly, for many reasons, and hummingbirds face what could be a long and difficult period of adaptation. What keeps the volunteers returning is the knowledge that the work they do may contribute to scientific discoveries that help hummingbirds endure.

Despite their allure, hummingbird populations are not well studied, and no one knows for sure whether their numbers are rising or falling overall. Federal scientists, though, agree that hummingbirds in the Western U.S. are threatened by the loss of their breeding, wintering and migratory stopover habitat, as well as by climate change, which, among other things, affects the availability of their primary food -- flower nectar. In 2008, the U.S. Fish and Wildlife Service included seven hummingbird species in its list of highest-priority bird-conservation needs: Costa's, Calliope, Lucifer, rufous, Allen's, blue-throated and buff-bellied.

The information gathered around the West by the hundreds of HMN volunteers may be the best defense these hummingbirds have. And it's gathered one bird at a time. At the picnic table, Udick retrieves the net bag from the stand and begins the banding process. HMN protocol dictates that birds cannot hang on the stand for longer than 30 minutes. Once the number of birds in bags reaches the maximum Udick can band in 30 minutes, the trapping stops, and the trapper simply starts counting the hummers that enter the trap's perimeter. Banding provides information about a representative sample of the various local species, while counting gives an estimate of their relative abundance.

Udick checks to see if the bird has a band (it doesn't), and removes it from the bag, holding it in the palm of her hand. The bird doesn't struggle; instead, it seems to watch her intently. "Can everybody see his beautiful red gorget when the light hits it?" she says to the new recruits and other observers. "This guy's a broad-tailed male. They're the ones that make that really loud trilling sound when they're flying, and that's because of the special shape of their outer flight feathers."

Several other species occur at Mesa Verde, including the black-chinned, which breeds in the area, and Calliope and rufous, which both migrate through. Udick keeps track of all kinds of details, including the amount of fat in the bird's breast and other areas (fat helps sustain birds on long migrations), and the presence, or absence, of pollen on the head and bill, which shows whether there are nectar-producing plants nearby.

Udick is very careful not to injure the birds she bands. She has even made a model hummingbird out of little yarn pompoms in order to teach volunteers how to handle the tiny birds. She picks up a minuscule numbered band; 75 of them would fit on the surface of a penny. Volunteer Lee Rogers has customized tools for smoothing and shaping the bands, and has created a tool for measuring birds' legs to ensure a perfect fit. Udick reads out the number on the band so that Pedersen can record it, then closes the band around the hummingbird's tarsus. All of the data collected is sent to the Bird Banding Laboratory run by the U.S. Geological Survey and the Canadian Wildlife Service, which makes it available for use by scientists and the public.

"What has thrilled us the most this past year is the start of our Four-Year Club," says Udick. "Those are the hummingbirds that we've trapped and banded every year of our four years of monitoring out here." They've already seen some five-year hummingbirds this year: "We joke about how we should get them gold bands."