The use of satellite systems for the study of bird migration

The Argos satellite system, with two or more polar-orbiting satellites, provides the basis for receiving radio signals from transmitters and for estimating locations of those transmitters anywhere around the earth. We briefly relate the development of platform-transmitter terminals small enough to be placed on birds, but powerful enough to send signals to the satellites. We review the use of this recent technology in avian studies, including several applications to bird migration. We also describe the type of information we are obtaining from three of our current studies of migratory birds.