Oriole Banding
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One of the most important projects that scientists do to learn about birds is putting numbered rings on the legs of wild individual birds. This is called bird banding. In the United States, all scientists who band birds work under the Bird Banding Laboratory of the U.S. Geological Survey. In Canada, bird banding orithologists work under the Bird Banding Office of the Canadian Wildlife Service. Because birds don't pay a bit of attention to what country they're in, and don't even notice when they cross a border, both countries work together to keep records of banded birds.
Capturing Orioles to Band Them
To capture orioles for banding, scientists usually set up hard-to-see nets
called mist nets. Songbirds get tangled in the nets. Then researchers
untangle them and put the band on their leg. The birds' measurements and
often their weights, their age (if it can be determined) and sex are recorded
along with the band number. This information is sent to the banding office.
If any person finds a dead bird with a leg band, they follow these steps:
Remove the band, or copy its number, and send to the banding laboratory along
with the date, place, and other information about the dead bird. The banding
office adds the information to their data base. The laboratory sends a postcard
to the bander informing him or her about the bird. A postcard is also sent
to the person who found the dead bird, telling when the bird was originally
banded.
Thousands of Orioles
As of September, 2000, the Bird Banding Laboratory had collected records on
thousands of orioles.
|
|
Baltimore Oriole |
Bullock's Oriole |
|
Total Number Banded |
87,697 |
11,455 |
|
Number Recaptured or Found Dead |
755 |
218 |
Why have so many more Baltimore Orioles been captured than Bullock's? Partly because there may actually be more Baltimore Orioles than Bullock's. There's probably more appropriate habitat for Baltimore Orioles than for Bullock's Orioles. But the difference in the number banded may also be partly due to another reason: Over the years, many more bird banders have lived and worked in the eastern half of North America than the western half, where Bullock's live.
Why So Few Recoveries?
Orioles weigh about an ounce and a half. Most of them are killed by predators
who eat the evidence. When they are killed or injured at communications towers,
many of them are picked up by cats, foxes, crows, and other predators and
scavengers, and are never found by people. Birds that die at windows are
the ones most likely to be found by people. Unfortunately, many people don't
pay attention to the tiny aluminum band on a dead bird's leg. One reason
that orioles don't get recaptured often may be that orioles that DO get tangled
in mist nets might start paying closer attention so it doesn't happen again!
Try This! Data Analysis
What percentage of all banded Baltimore Orioles are recaptured or found dead? What percentage of all Bullock's Orioles are recaptured or found dead?
Compare banded oriole data (shown in the table above) to data about Canada Geese and Mallards from the same time period:
|
|
Canada Goose |
Mallard |
|
Total Number Banded |
2,991,538 |
5,935,960 |
|
Number Recaptured or Found Dead |
594,114 |
878,704 |
Calculate the percentage of banded geese and ducks that are recaptured or found dead. Then discuss these questions:
- Why are so many more geese and ducks banded than orioles?
- Why are so many more geese and ducks recaptured or found dead than orioles? (HINT: Think about the main way that geese and ducks die.)
After you've thought about and journaled or discussed these questions, see how Journey North's ornithologist Laura Erickson answered them here.
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