A small herd of Rocky Mountain mule deer ( Odocoileus hemionus hemion-us ) was kept in an enclosure during the fall months of 1955 in order to secure known aged embryos. As a subsidiary project the behavior of this herd was observed. It was felt that this ancillary study would be useful to us and possibly to others for future use in handling confined mule deer. This investigation was made possible through the cooperation of the U. S. Fish and Wildlife Service, Montana Fish and Game Department, Montana Cooperative Wildlife Research Unit, and the Research Council of Montana State University to whom grateful acknowledgement is made. We are indebted to Artemus R. Davis for technical assistance during the project. Materials and Methods —A corral at the National Bison Range, Moiese, Montana, was made available for this project. The corral was roughly 130 feet long by 45 feet wide, running in a NE-SW direction, with a partitioned area 23 feet from one end used as an isolation pen for the buck. A plank fence 7–8 feet high surrounded the entire enclosure. This fence and the partition fence were covered with burlap to a height of 7 feet leaving a gap of one foot at the base of the fence. An enclosed observation tower was built above one corner of the buck's pen overlooking the does' corral. The floor of this hut was about seven feet above ground level, and in it was kept all essential equipment. Alfalfa hay and stock pellets were provided by the Montana Fish and Game Department. Hay was invariably fed first each morning, stock pellets were usually fed then also, and hay might be fed again in the late afternoon depending on the weather. An electric water heater kept the water tank open throughout the observations. A reading of …