Banding sparrows and warblers, while assessing habitat health

The song sparrow was tangled in a mist net stretched between a stand of big bluestem and a blackberry thicket. It flapped and flailed, but settled a bit as Alicia Bachman’s nimble fingers worked to extract it – first the tiny claws and legs, then the wings and finally the head. A volunteer and experienced bander, Alicia made it look deceptively easy. She cradled the sparrow in her palm then tucked it in a cotton bag. We walked the fresh-mown path to the station where the bird would be assessed and banded.

We captured dozens of song sparrows and other species that warm and sunny day in mid-October. It was an auspicious start to an ongoing effort to collect data about birds in the early successional habitat we’ve created in the Uwharries. We hope to learn more about the populations that are using the areas we’ve converted from fescue to native, warm season grass. Do we have all the expected species? Are we hosting any unusual species? Are certain species benefiting more than others? Is the habitat producing and sustaining healthy birds? Answering these questions about the sparrows and other birds in our grasslands might help us – and others – make better management decisions.

Back in the day, ornithologists would have “collected” the birds and taken the carcasses back to the lab for study. Fortunately, scientists now employ nonlethal means. They capture birds in mist nets, quickly assess them in the field, then release them with a band attached to their leg. Banders adhere to strict protocols – governing factors such as weather conditions and length of time a bird remains in the net – to minimize stress on their captives. Banding is a science and an art. It takes practice and patience, and it requires a permit from U.S. Fish and Wildlife Service, one of the agencies spearheading this study. We also have high school and college students volunteering their time for the chance to train with experienced banders.

At the banding station, the first order of business is to determine the species, which can sometimes be challenging in fall, even with a bird in hand. This time of year, many adults have lost their distinctive breeding plumage and juveniles haven’t come into theirs yet. Sparrows are notoriously difficult, colored up with subtle variations of brown, rust, gray and buff. While we have only five species in the Piedmont during breeding season, another half-dozen species arrive to spend the winter and a few others potentially pass through during migration.

Alicia measured the length of the wing, then got a weight by sticking the bird head-first into a medicine bottle and putting it on a sensitive scale. I logged her results on a data sheet as she continued her assessment. She blew on the sparrow’s chest, separating the feathers so she could gauge its body fat. This can tell you a lot about the quality of habitat and the stress of migration. She also blew the feathers on the back of its head to get a view of its skull. The skull won’t be fully fused if the bird hatched during the current year’s breeding season. The condition of the wing and tail feathers also provides clues about the bird’s age. Unless the plumage was obvious, we didn’t attempt to sex the birds. Typically, the brood patch and cloacal protuberance are assessed only during breeding season.

Finally, Alicia attached a metal band to the song sparrow’s delicate leg, crimping gently with a pair of special pliers. The unique number will allow the bird to be identified if it is recaptured here or elsewhere. This can provide information about how long a bird lives and where it goes on migration.

It was an exhilarating and exhausting day. We were smitten with a spiffy white-crowned sparrow, a winter resident in the Piedmont, and always thrilled to have a common yellowthroat or palm warbler in the mix. During the afternoon lull when the nets were empty, we turned our attention skyward and saw several species of raptors, including a bald eagle and migrating peregrine falcon. Unfortunately, a black-billed cuckoo, which isn’t seen often in the Piedmont, also eluded the nets.

I took my first steps as a bird bander, recording data and extracting grasshoppers from the nets, but I doubt I’ll ever work up the confidence to handle a warbler or sparrow. My passion is providing the habitat. The day we were testing the equipment, we captured a Tennessee warbler, one of the “confusing fall warblers” that can be difficult to identify in the field. It breeds in the forests of New England and Canada but prefers brushy habitat during migration to the tropics.

Knowing the Tennessee warbler was taking advantage of our recently established grasslands in the Uwharries makes me think we’re doing something right. When it comes to helping us understand and manage our habitat, a bird in the hand might indeed be better than two in the bush.