Low-tech leg bands and high-tech solar-powered backpacks help us unravel mysteries about birds' lives.
The handsome crow in the photo accompanying this story may look like other crows, but we know some unique things about this bird: He's two years old, spends part of his day at a large composting facility and was busy this past summer helping his mother raise her new brood. Unhappily, those younger crows didn't survive, so N7 is back to being the baby of his family.
Chickadees look alike, too, but note the left leg of the chickadee in another photo: That lightweight green tag makes him less of an enigma. Thanks to tag readers installed on bird feeders in his area, we know how often he visits feeders, how many seeds he takes each time and the feeding route he follows each day. This kind of information is opening up whole new avenues in our understanding of bird feeding and breeding behavior.
And that white pelican with the backpack is wearing the latest wrinkle in tracking technology, a solar-charged Global Positioning System unit that tracks its every move. Knowing where this bird is and where it's headed at any moment is invaluable to wildlife managers looking to preserve areas where it rests and refuels on its way to and from the Gulf of Mexico.
We humans have always wanted to learn more about the birds that live around us, and it's becoming easier to satisfy that urge. Really, it's a necessity in many cases, as more bird species face human-caused stresses and threats to their survival.
Most of what we know about birds we know because humans have devised ways to single out an individual bird to tell it apart from others of its flock or species. Devices have evolved from metal bands on bird legs to transmitters on their backs. Tracking devices used to be limited to big birds, like osprey, that could carry the weight. But they're now small enough to be used on 2-ounce songbirds, such as purple martins.
How do we know how long birds live? Banding records maintained at the federal Bird Banding Laboratory provide a good indication of a bird species' longevity. How do we know which routes ospreys take on migration? Radio transmitters on the birds' backs finally solved this mystery (and highlighted the importance of preserving stopover sites in the Caribbean). How do we know whether a bird is more endangered during migration or during nesting season? Tracking technology is invaluable here.
Old tech, new tech
Many of us have watched a bird bander clamp a metal ring to a captured bird's leg, a practice that dates back at least 400 years, when royal falcons wore bands. Later, in the early 1800s, naturalist and artist John James Audubon tied silver cords to the legs of young phoebes in a nest. He was delighted to be able to tell that the same birds had returned to his neighborhood the following year, silver cords still attached.
When we can tell one bird from another, we can know individuals. Without this ability, analyzing what birds are doing and why they're doing it is mostly guesswork.
"Being able to identify individual birds is extremely important to the work we're doing with crows, and it has revolutionized what we know about these birds," says Kevin McGowan. An instructor at the Cornell Lab of Ornithology in Ithaca, N.Y., and a renowned crow expert, McGowan has banded more than 2,000 of Ithaca's crows.
Those harmless wing tags that McGowan clips to a crow nestling instantly identify each bird and indicate which family it belongs to, as well as the year it hatched. McGowan and colleagues follow these crows as they move through their daily lives around Ithaca, which is why he knows so much about N7.
Fitting local birds with tags that are read by a transponder (similar to the way packages are tracked) intrigues Duluth naturalist and author Laura Erickson. But one system doesn't necessarily supplant another, and her dream is to have the chickadees in her back yard marked with colored leg bands.
"This would help me work out flock hierarchy issues and have firmer evidence of individual differences in behavior," Erickson said.
As for the pelican, Mark Martell, director of bird conservation for Audubon Minnesota, notes that the satellite tracking technology provides "incredibly accurate data about a bird's movements." The one drawback: The devices are expensive, running about $3,500 each. (In this case, because the birds in the study spend part of their lives on the Gulf of Mexico, the pelican project earned a grant from mitigation funds set aside by BP after its massive oil spill in 2010. Check on the pelicans' progress at mn.audubon.org/follow-bird-interactive-map.)
Our ability to mark and track birds is telling us where they travel on migration, how they use a neighborhood's resources and hint at how we might help make their lives easier. But while it's true that we're making great strides in our attempts to better understand birds and their lives, we've only begun to unravel their many mysteries.
For such a ubiquitous and widespread species, crows still aren't well understood. Kevin McGowan's tagging and tracking of them in Ithaca, N.Y., has proved beyond a doubt that young crows often defer mating for several years to assist their parents in raising the next generation. This is called cooperative breeding and is very rare in the world of birds.
Some other ways of knowing:
Geo-locators: These tiny devices measure light at various times of the day throughout the year, giving an indication of longitude and latitude. When researchers re-catch a bird, they can tell generally where it traveled, and the route it used to get there.
Web cams: Stationary cameras are placed on bird nests and inside nest boxes, and provide a wealth of information about nesting behavior.
Stationary sound recorders: These pick up sounds in the natural world, including bird calls and songs, and are being used in conjunction with efforts to trace ivory-billed woodpeckers.
Radar: NexRad records masses of birds, showing the density and direction of migration flights.
Bird censuses: Christmas bird counts and other citizen science efforts give a snapshot of bird activity on a given day or week.
Want to watch a bird bander at work? Visit Springbrook Nature Center in Fridley to observe Ron Refsnider conduct banding activities. Families and children are welcome and attendance is free. A schedule is available at www.springbrooknaturecenter.org, then click on the "Education" link. Banders may also be observed at Lowry and Eastman Nature Centers, check www.threeriversparks.org/events/Groups/birding-programs.aspx for the schedule.