Gray Catbird, Dumetella carolinensis

Scientists can keep track of individual birds by placing aluminum and/or colored bands on a bird’s legs. Each set of bands has a unique combination of colors and numbers. Every time a scientist bands a bird, he or she records the location and date as well as the bird’s species, gender, estimated age and other features, and sends that information to the lab. The capture and banding are done by highly-trained researchers to ensure the birds’ well-being. The US Geological Survey works with The North American Banding Council, which develops banding materials and addresses safety regulations.

Through banding research, scientists can learn a bird’s routine, such as where they spend most of the day, where they migrate, what they eat and how much habitat they need to feed and reproduce. This information can help identify priority areas for conservation.

Banding data can reveal other trends in life span and population. If there is a change in the age of birds caught at a certain location, life expectancy may be getting shorter or longer. The number of birds captured overall may indicate whether populations are increasing or in decline. Data such as weight and wingspan can show trends in overall health. Such insight can cue scientists to look for changes to birds’ food sources, predators, competitors, habitats or other factors that affect their survival and reproduction.

Banding, or ringing as it is called in Europe, has provided important information on the movements of birds but little about what the birds did between banding and later band recovery.  Recent research with new techniques and equipment has provided considerably more information. Besides systematic field observations, radar, chemical isotopes, radio frequency identification tags, very high frequency radios, videography, and more recently GPS loggers, often combined with satellite tracking, have been employed. The British Antarctic Survey uses fingertip-sized data loggers attached to the legs of sea birds to record light intensities at different latitudes and longitudes, to provide position information. Even smaller loggers are being made as light as .05 oz (1.5grams) to be used on songbirds. A study of Black-throated Blue Warblers measured naturally occurring isotopes of carbon and hydrogen in the birds’ feathers, the ratios of the isotopes reflecting the birds’ diets, determining that the northern breeding populations winter farther west in the Caribbean than do the southern breeding populations. Most of these techniques are expensive and require considerable training on the part of users, so bird banding will continue to be a primary source of data on bird movements.

Bird banding can have an impact on the survival of birds. Bands can cause injury from friction against the leg, they add a bit of weight to the bird, and capturing the birds causes stress. Neck bands on Trumpeter Swans have iced up, causing the birds severe mobility problems and the aluminum bands put on the flippers of King Penguins appeared to result in a 16 percent higher mortality rate. Banders argue that these problems are exaggerated and that the information gleaned from banding is worth the risk, but I suspect the procedure will slowly be supplanted by new techniques as they become more accessible and less expensive.

The Bird Banding Laboratory (Est. 1920), an integrated scientific program, supports the collection, curation, archiving, and dissemination of data from banded and marked birds. These data allow for developing effective bird science, management, and conservation. The lab, in collaboration with the Canadian Wildlife Service Bird Banding Office, administer the North American Bird Banding Program

Notice that the catbird, above, has a small radio transmitter attached as well.