They are being used increasingly in studies of behavior and ecology, often involving large numbers of individuals. When used in combination with aluminum bands, plastic bands must be of the same size. Depending upon the duration of the study, it may be important to consider that some colors of commercially available celluloid bands fade. UV-stable bands are available from several suppliers. Most colors of UV-stable plastic remain bright for several years unless covered with an obscuring substance such as dirt or algae.
Blue bands fade relatively quickly.
In recent years, students of long distance migrants, especially shorebirds, have employed plastic flags with unique colors representing different countries, e.g., green for U.S.A., and different positions being used to represent points of origin. The flags are larger and more conspicuous than bands, thus allowing sightings over longer distances. Given a philosophy that the manipulation of wild animals should be the minimum necessary for the study, flags should be used only when they provide a substantial advantage over normal color bands. The use of flags on newly hatched chicks is discouraged. The use of constant numbers and relative positions of bands can help verify the correctness of reports of marked birds.