Bird-banding exercise offers weighty lessons

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Next time you have two nickels in your pocket or purse, take them in the palm of your hand and feel their heft. What you have is the weight of the average male house wren, a small brown bird with a great singing voice. Two nickels weigh 10 grams. Add a dime to your hand and you’ve actually exceeded the weight of a female house wren, which averages 12 grams.

My wife, Jean, had the chance to hold such a little wonder on a Sunday morning just a few weeks ago. We went to see how bird banding is done, and Jean was allowed to release the wren after it was processed.

Ron Refsnider headed a bird banding team at the Carl and Janet Schuneman Wildlife Area, just north of Dellwood in Washington County. Refsnider is one of 3,000 licensed master bird banders in the United States. He’s also a U.S. Fish and Wildlife Service staffer, specializing in endangered species, including the gray wolf.

Birds are captured in mist nets, 12 meters long by three meters high, which are designed to hang with loose pockets across the length. Refsnider’s crew of 11 volunteers had 16 nets set up throughout the wildlife area that morning.

When a bird flies into the net, it drops into the pocket. The banding team then gently untangles the bird, puts it into a small cloth sack that looks like a miniature pillowcase and ties the top shut.

The “bagged” birds are brought to the banding station, a picnic shelter, where Refsnider has set up his equipment and logs. There a volunteer carefully removes the bird from the cloth bag and transfers it to a zippered mesh bag before weighing it.

Based on the species, Refsnider selects the appropriate leg band from a set of 22 band sizes. He reads the number embossed on the band so the volunteer can enter that number on the log sheet.

After the weigh-in, Refsnider takes the bird and, using special pliers, first spreads the selected band open, then puts it around the bird’s leg and gently closes the band, without putting pressure on the leg itself.

Then, while he has the bird in hand, Refsnider examines and measures the bird, dictating the information to the volunteer maintaining the log. He measures wing and tail length. Wing length alone is useful in determining the sex in some species.

He also holds the bird’s belly up and gently puffs to raise the feathers on the bird’s underside. This allows him to examine several things.

First is the amount of fat stored on the chest, which can give a clue to the bird’s migratory status. If a bird retains a great deal of fat, it probably hasn’t completed migration and will be taking off for points north as soon as it gets an evening with a favorable wind. A bird with little or no fat reserve has either completed its migration or just arrived, and will take a day or two to replenish its fat stores before continuing its migration.

Examining the chest also shows whether there is a “brood patch,” a patch of skin where the blood supply lies close to the surface. This indicates a female bird that has been sitting on eggs, warming them with her chest.

An examination just below the belly can also reveal the bird’s sex. Males have what is called a cloacal protuberance, evident only during breeding season.

Refsnider looks at feather wear and color. Older, unmolted feathers are faded and lighter than newly replaced ones, which is another clue to the bird’s age.

All of these facts and statistics are entered next to the band number on the log page by the volunteer seated next to Refsnider. When all the measurements and assessments are completed, Refsnider releases the bird or may hand it to another person to release.

The bird is turned right side up in one hand, with the other hand gently over the top, as the handler steps away from the banding table into a clear area. When the upper hand is removed, the bird flies away, usually to a nearby tree, where it spends a few moments realigning its feathers before heading off to continue its day. The entire process from weighing to release usually takes five to ten minutes.

The house wren that Jean released had been banded last year and had been caught twice already that morning. Refsnider supposed that the wren was feeding nestlings and the mist net was right on its route between nest and food source.

Refsnider does bird banding year-round at Elm Creek Park Reserve in western Hennepin County, Springbrook Nature Center in Fridley and in his back yard. He’s at Schuneman Marsh twice a year or so. All of his bird banding is done on a volunteer basis.

Refsnider says he’s especially interested in winter bird-banding because it can reveal details about site fidelity, that is, how often birds return to the same sites in the winter. But he can’t use mist nets in winter and has to resort to live traps, near feeders or other food sources.

Banding birds is useful in research and management projects. It helps scientists study migration patterns, habitat preferences, breeding sites, behavior, social structure, disease and toxicology, lifespan, survival rate, reproduction success and population growth. The federal government uses banding data collected from waterfowl to help determine hunting limits for different species.

The first bird bander in America is generally agreed to be John James Audubon, who in 1883 tied silver cords around the legs of phoebe nestlings in Philadelphia to see if they’d return to the same place next year. Several of them did.

Perhaps the next time you have a few coins in your hand, you’ll think about how delicate those little birds around us really are. And if you happen to see a phoebe with a silver cord around its leg . . . .

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