Insights from the field: Bird banding documents avian populations and migration
Shimmering fields of plants blanketed with ice crystals greeted me as I arrived at Georgia’s Panola Mountain State Park in the early morning light. I trudged along a well-beaten path along with other volunteers with headlights to set up large swaths of thin black netting stretched taught between two poles, known as mist nets. The steel poles were practically frozen together in the cold red clay soil. A major cold front blew through several days earlier, pushing out the last of the flocks migrating South. The nets would catch birds flying through the area this morning for banding. The birds banded today would likely be local residents for the winter.
We made an efficient crew, with four licensed bird banders and a number of experienced and less-experienced volunteers. Once nets were assembled, we met up at the banding table to discuss each person’s role as a bander, extractor, or transporter for the birds that would start stirring at any moment. Just before sunrise, the first songbirds began flying into the mist nets. The designated extractors meticulously and safely untangled the birds from the nets and placed them into cotton bags to keep them calm, then the transporters carried them to the banding table. The banders carefully removed each bird from its pouch, checking their legs for a band and adding bands to those birds without one. Each bird was checked and measured, then the bander’s hand opened to send it gently flying back into the field.
Charlie Muse, the federally-licensed master bird bander who has held the permit to band birds at Panola for the past 13 years, took time while managing the morning’s operation to answer questions about his work and its impact. Fascinated with reptiles and amphibians from an early age, Muse discovered birding in college. He recalled spending the summer of 1992 on an island off coastal Maine. “I came across these people with nets hanging out in the scrub catching birds, and I thought that was just the neatest thing in the world. I started hanging out with them in between my classes…and the next year they invited me back for a class to learn how to band birds. I’ve been banding ever since.”
We banded over 20 birds that icy morning. The first bird was a sparrow so cold that Mr. Muse slipped it inside the pocket of his insulated hunting overalls with a hand warmer. We also captured a Northern Mockingbird that complained loudly and a fluffy Eastern Phoebe that sported head feathers ruffled like bed-head. We netted two charismatic Eastern Bluebirds and a streaky Vesper Sparrow, which is less commonly seen in that area and required more extensive identification verification. The bander gave each bandless bird a little numbered metal band, like a personalized bird anklet. Some species, like Eastern Bluebirds and Field Sparrows, received two extra colored bands to provide additional tracking information for different scientific studies. For every bird brought to the banding table, the bander made a series of measurements, such as wing and tail feather lengths, belly fat content, and body weight, as well as sex and age. Another volunteer tediously recorded all of this information on a clipboard of data collection sheets, as well as the identification number on the bird’s new or existing band.
Data collected from bird banding assists scientists with avian conservation. “If you want to conserve something, you need to understand it. You need to understand its needs, you need to understand its phenology, and what its population is doing. You need to understand its dynamics,” said Muse. “There’s some knowledge you can only get from handling birds, from marking them, from being able to recognize individuals…there’s a lot of information you can get from banding that you can’t get from other means.” With 13 years of banding data, Muse’s intent with the Panola banding station’s location is to “[collect] data to monitor the changes in bird populations over time as the Department of Natural Resources restores the land to native warm season grasses.”
Scientists at the Odum School of Ecology at the University of Georgia use banding data in avian disease research. Bird banding can be used to identify the bird if it is caught again, according to Dr. Sonia Altizer, a professor at the Odum School of Ecology. “Banding added to early knowledge of bird survival, migration, and reproductive success,” noted Dr. Altizer, adding that newer “tracking technology usually goes hand in hand with bird banding [in recent years] and has added enormously to knowledge of bird behavior and movement.” Geolocators and GPS transmitters are examples of these newer technologies which can track precise location, often even if the bird is not recaptured.
Extensive banding databases like the North American Bird Banding Program, which has records for over 38 million migratory songbirds banded since 1960, allow scientists to analyze bird migration relative to environmental data. A recent survey shows that almost 30 percent of North America’s bird species have disappeared over the past half-century.
“[Bird banding] had been a standard practice in traditional ornithology in the last 50 years,” said Dr. Andy Davis, a Research Scientist at the Odum School of Ecology and master bander. “Even today, there are still researchers who are analyzing the banding data and making new discoveries from it.” According to Dr. Davis, “more technological approaches for tracking birds have been developed,” and scientists are even able to “take a feather from a bird and use sophisticated chemical analyses of the feather tissue and figure out where the bird came from.”
As bird populations shift migration patterns and species diminish, bird banding provides longitudinal monitoring and critical data needed to understand the adverse effects of accelerating climate change on global bird species. Recent advances in technology will provide additional insight into avian location and population dynamics. Capturing sparrows and banding data with today’s mist nets will inform research to forestall tomorrow’s threats of species extinctions.