Measuring an American Avocet

U.S. Geological Survey Wildlife biologists take physical measurements of an American Avocet in Malheur National Wildlife Refuge. Using digital calipers, the birds culmen, or bill, is measured from the tip of the beak to the feather line. Still using the calipers the bird's legs are measured. Lastly the scientist takes a measurement of the wing length with a ruler. These basic measurements can be useful to identify species, identify difference between the sexes, age or otherwise characterize individual birds.