Migration
In 1822 a stork was shot in Mecklenberg-Western Pomerania in northern Germany. In its neck was a long spear later identified as belonging to a central African tribe. That bird and 25 others found later with spears or arrows imbedded in their bodies were called Pfeilstorch, “arrow stork” (left). These discoveries led to the knowledge that the birds wintered in Africa. The idea of annual avian migrations was eventually accepted but some people still could not imagine how the wagtail, a European songbird, could possibly cross the Mediterranean or how hummingbirds could traverse the Gulf of Mexico. They conjectured that wagtails rode on the backs of storks while hummingbirds hitched a ride on Canada Geese.
We know migration is essential for the survival of some species of birds, but the whys and hows of migratory behavior are still being discovered. Why do some but not all birds migrate? Why do some migrants fly non-stop for days and others seemingly take their time? Is the path of migration instinctive or learned? Do birds follow established routes? Until scientists found ways to track birds, these were all mysteries, and all the answers are not in yet.
The study of migration began by marking birds with tags or bands. As far back as 2000 years B.C. the Chinese kept birds for falconry, each one marked to indicate ownership. Early Romans sent simple messages across the countryside by tying threads to the feet of crows. Perhaps the earliest record of a metal band on a bird’s leg was in 1595 when a Peregrine Falcon belonging to Henry IV of France disappeared in pursuit of a bustard (a large, swift-running bird of the Old world plains) and later found on the island of Malta, south of Italy, 1350 miles (2250 km) away. A duck shot in Sussex in the UK in 1709 had a silver band around its neck inscribed with the arms of the King of Denmark. J.J. Audubon tied silver cords around the legs of young Eastern Phoebes and identified them later after they had become adults. But the first attempt to gather any real information about birds’ movements might have been the marking of a Great Gray Heron captured in Germany in the early 18th century. It had metal bands on its legs, one of which indicated it was banded in Turkey a few years earlier. In 1899 Denmark, C.C. Mortenson was apparently the first person to systematically mark birds with numbered bands to collect data on their travels.
In 1920 the Federal Fish and Wildlife Services of Canada and the U.S. began to oversee bird banding activities in the two countries. Over 64 million birds have been banded over the past 60 years, although most are never seen again. About 15-20 percent of waterfowl bands are recovered each year because they are hunted and if a duck dies in the wild, the aluminum band is big enough and will last long enough to be found someday. Band returns from songbirds are more like one percent because the birds have short life spans, relatively few songbirds are banded, and the bands are small. I was a licensed bird-bander for several years and banded a few hundred songbirds. Although I did recapture a few birds in the same location a year or two later, I never got a recovery from outside my banding site. I found two bands, each belonging to a different White Pelican and reported a live Tundra Swan with a neck band. The Bird Banding Laboratory of the US Geological Survey collects comprehensive data, requiring painstaking attention to detail on the part of licensed banders, resulting in extensive and accurate information on bird movements. In addition to the date of banding and recapture, information like age, sex, stage of molting, whether blood or feather samples were taken, if auxiliary leg or wing or neck markers will be used, and signs of disease are all noted. Banding is allowed under the provisions of the Migratory Bird Treaty Act, first enacted in 1916, which makes it unlawful to kill, capture, hunt, take or sell migratory birds, dead or alive, or any bird parts, including feathers, eggs, and nests, without a federal permit or license. One needs to have a legitimate reason for banding birds; it is not looked upon as a casual hobby.
Continue your education on migration at Why Migrate, Timing of Migration, Banding, and How Long Does Migration Take?