To establish some of the factors responsible for neonatal fawn mortality in a white-tailed deer (Odocoileus virginianus) population on the Welder Wildlife Refuge in South Texas, radio transmitters, constructed as collars, were placed on 34 and 47 fawns, 1 to 12 days of age, during 1965 and 1966, respectively. The collared fawns were relocated almost daily with a receiver and a directional antenna for a minimum of a month, or until death.

Frequent relocation of collared fawns allowed observation of their physical condition and provided fresh carcasses enabling determination of the causes of death. In addition, it was possible to measure movements and study behavior during this normally inaccessible period.

Radiotelemetry techniques and problems encountered during the study are discussed. The utility of radiotelemetry in studies of juvenile mortality, movement, and behavior was amply demonstrated.