FAIRBANKS — Delicately but firmly holding a Swainson’s thrush in her left hand, with the bird’s brown head poking out between her index and middle fingers, Sue Guers spread open its wing and examined it.

“This is actually a juvenile,” Guers said, studying the wing feathers. “The juveniles have a layer of coverts on their wing feathers. We call them buffy tips.”

She pointed them out to a reporter and a pair of tourists from California who had stopped by the Alaska Bird Observatory’s bird banding station at Creamer’s Field Migratory Waterfowl Refuge last Friday.

“That’s one quick way to tell the difference between juveniles and adults, to see if they have buffy tips,” Guers said.

Next to Guers sat Mitch Levenhagen, a volunteer assistant who was scribbling down data Guers was rattling off as she handled the bird. Guers proceeded to turn the bird over and started blowing on its chest and head to reveal the skin underneath.

She measured the length of the tail and wing, which helps determine the bird’s sex and age. She stuck the bird upside down in a cup and weighed it. Blowing apart the feathers on its chest and head, Guers gauged the bird’s breeding condition, fat level, body molt and level of skull ossification (bone layering) alll within a matter of a couple minutes.

“This guy doesn’t have any fat on him,” Guers said, turning the bird back over. “You can tell muscle tissue from fat tissue. Muscle tissue is deep maroon color and fat tissue is orange in color. All I’m seeing is muscle.”

The bird needed to fatten up before heading south to a warmer climate for the winter, she said.

“This guy’s going to Central America; he’s got a long way to go,” Guers said. “He’s not ready to go south yet.”

96,000 and counting

All the information Guers and her banding crew collect, on this and the thousands of other birds they handle, will eventually be sent to the U.S. Geological Survey’s Bird Banding Lab in Patuxent, Md., where it will be entered into a huge database that includes information from banding stations from around North America. Researchers use that information to detect trends and patterns in bird populations, such as range expansion and migration timing.

“Birds are indicator species; they kind of tell us what’s going on in the environment,” Guers said. “One of the ways we can monitor songbird populations is to band them.

“A lot of other places with longer data sets are finding their birds are arriving earlier,” she said. “I’ve looked at our long-term data set and it looks like that’s happening with some of our short-distance migrants like dark-eye juncos and robins, but it’s hard to say for the long-distance migrants. Twenty years sounds like a lot of time, but it’s kind of a blip on the radar screen.”

Lastly, Guers measured the bird’s leg to determine what size of metal band to put around its ankle. There are nine band sizes, the smallest of which is so tiny it’s hard to imagine how it could hold nine identifying digits on it, but there are. “Just like a social security number,” Guers said. If a bird is recaptured elsewhere, the numbers tell researchers when and where the bird was banded.

Of course, that doesn’t happen very often. Of the more than 96,000 songbirds banded at the ABO banding station since it opened in 1992, only 20 — an average of one per year — have been recaptured outside of Alaska.

“We’re banding about 5,000 birds a year,” Guers said.

Functional, not fancy

Officially called the Creamer’s Field Migration Station, the ABO’s banding station is the farthest north banding station in North America and one of three in Alaska. The U.S. Fish and Wildlife Service runs a banding station in Tok and the Bureau of Land Management manages a banding station at the Campbell Creek Science Center in Anchorage, but both those stations operate during the fall migration only.

“We’re the only station in Alaska to operate a spring banding station,” Guers said.

Consisting of nothing but a small white vinyl weatherport built on a wooden platform in the woods at Creamer’s Field Migratory Waterfowl Refuge, the ABO banding station isn’t fancy but it’s functional.

The weatherport gives Guers and her crew a dry, semi-warm place to examine birds and collect data. There is a heater, but Guers keeps it turned down so as not to shock the birds.

They capture birds using lightweight, nylon mesh nets, called mist nets, which are strung up in a patch of woods behind Creamer’s Field. The birds fly into the nets, which are practically invisible, and get their feet tangled in the webbing.

Banding technicians check the nets every half hour to collect any birds caught. The injury rate for netted birds is less than 1 percent and the mortality rate is almost negligible, Guers said.

“Birds are really resilient,” she said. “We’ve caught birds that had injuries and caught them again later and their injuries have healed.”

The nets — 22 in the spring and 30 in the fall — are put up from late April to early June for the spring migration and from mid-July through September for the fall migration. They are up for 6 1/2 hours per day, seven days per week. For consistency, the nets are set up in the same place each spring and fall. There are 22 nets set up in the spring and 30 nets set up in the fall.

Significantly more birds are caught during fall because young birds join the mix. Songbirds produce four or five chicks per year, Guers said.

“For every one adult, we catch nine juveniles in the fall,” she said. “Our juvenile catch rate is out of this world.”

The ratio of adults to juveniles gives researchers an idea which species have been more productive during the summer, Guers said.

Even after 15 years of banding birds, Guers, 37, never ceases to be amazed by what birds go through to get where they’re going. Take the blackpoll warbler that was banded in Fairbanks in 1999 and was then recaptured in Ohio later the same year.

“This is a 10-gram bird that goes all the way across Canada and hops off at the tip of Maine and goes to Cuba or South America,” she said increduously. “They do it year after year. They’re the size of two nickels and they’re flying 61,000 miles one way.

“They know where they’re going without any help,” Guers said. “I have a hard time finding my keys in the morning.”

Valuable volunteers

The banding station at Creamer’s Field wouldn’t still be in business if it weren’t for people like Joanne Haller, one of about 70 volunteers who help check nets, collect birds and record data.

Because you need trained professionals to handle birds, it’s expensive to run a banding station, Guers said, which is why many banding stations that were set up in the early 1990s are no longer in existence.

Haller, 77, has been volunteering at the Creamer’s Field banding station since it opened 20 years ago.

“My sister moved here in 1992 and I came to visit her,” recalled Haller, who lives in Colorado. “One day I came out here and they were shorthanded and the man who was running the station handed me a bird and said to someone, ‘Teach her what to do.’”

That would have been Tom Pogson, one of the founders of the ABO.

Every year since, Haller has returned in the fall to extract birds from the nets for three or four weeks. It gives her a chance to visit her sister and use the biology degree that she earned in college.

“Back when I graduated from college, it was tough for a woman to get into anything like this,” she said.

Haller was making her rounds last Friday morning, wearing a fleece vest over her maroon Alaskan Amber hooded sweatshirt.

“We’ve got one way up here,” she said as she approached the third net in her five-net circuit.

A fluttering Swainson’s thrush hung upside down, its feet tangled in the net about 20 feet up.

“One trick is to be sure that you’re getting them from the right side,” Haller said as she loosened the net on both ends and pulled it down so she could reach the bird. “You want to back them out. You don’t want to take them all the way through.”

The bird was caught between folds in the net, making it tricky to get to. It took a minute of net and bird wrangling, but it wasn’t long before Haller was stuffing the bird into a small cloth bag that she then attached to a carabiner hanging from her neck.

Holding up her hand to reveal a purple blotch of bird poop, Haller smiled. “Hazard of the job,” she said, wiping her hand clean.

Haller attached a clothespin with a number on it to the bag, which tells the data takers which net the bird was caught in. Then she raised the net back to where it was, tied it in place and continued her rounds.

There are worse ways for a 77-year-old woman to be spending her time than walking around the woods on a beautiful day in Alaska, untangling birds from nets, Haller said.

Educating the public

Back at the station, the two California tourists, Kathleen and Tony Kent, were still hanging around when a new batch of catches came in.

The banding station gets about 500 visitors a year, not counting the thousands of school children who visit the station each spring and fall as part of educational programs.

With cameras and binoculars draped over their shoulders and around their necks, the Kents looked every bit the part of birdwatchers.

“She’s out of control,” Tony Kent, 73, said of his wife’s interest in birds.

“He’s an S.O.B.,” responded Kathleen, 66, with a laugh. “Spouse of a birder.”

The Kents drove to Alaska and found out about the Creamer’s Field banding station at the visitors center in Tok. They made it a point to stop by when they got to Fairbanks. They spent an hour watching birds being banded and asking questions, all of which were answered by Guers and her crew. Kathleen even got to release a Swainson’s thrush.

“I’ve been wanting to go to a bird banding station to see how it works,” Kathleen said. “I appreciate all the work people do to conserve birds and wildlife.”

Those words brought a smile to Guers’ face.

“Our banding station is great because we’re getting research on birds and we’re educating the public,” Guers said. “We’re telling people about birds and conservation and what they can do to help them.”

Contact outdoors editor Tim Mowry at 459-7587.