As corvids are documented nest predators, we study the productivity, survivorship, and dispersal of American Crows at a subset of our study sites. Marking individuals is essential for estimation of survivorship and dispersal. Thus, each year we mark a many birds with a unique combination of colored legbands so that we can identify individuals with binoculars. Some crows are even fitted with a radio transmitter that emits a pulse over a unique radio frequency so that they can be tracked over long distances. The ability to detect dispersing juveniles over long distance became evident when one of the birds marked near the University of Washington moved about 30 miles NE to the town of Index.
Birds carrying transmitters do so with a harness made of teflon webbing.
The harness is designed to degrade after 1.5 years, the approximate life of the transmitter's battery. Please note that understanding the processes causing bird communities to change with urbanization necessitates the capture and marking of individual birds. These activities demands a great deal of training and are heavily regulated. For more information on these activities see the Migratory Bird Treaty Act and the USGS Bird Banding Lab's homepage. Undergraduate students help us collect data in the field.