[en] Data are presented from the radioanalysis of tissues collected from cattle, mule deer, desert bighorn sheep, rabbits, feral horses, and other wildlife that resided on or near the Nevada Test Site. Routine activities and special investigations of the Animal Investigation Program are also discussed. Other than potassium-40, gamma-emitting radionuclides were detected infrequently. Strontium-90 concentrations in bones from deer, cattle, and desert bighorn sheep continued the downward trend of recent years. Tritium concentrations were generally within expected environmental limits with the exception of animals exposed to sources of contamination. Radionuclide tissue concentrations were generally higher in the tissues of animals residing in Area 15 than in other areas. Statistical analyses made of plutonium-239 levels reported in cattle tissue collected from 1971 through 1977 reveal that activity levels in lungs, liver, and bone are significantly related to age. Activity levels did not change significantly in the ingesta and lungs during this time but did tend to increase for bone and liver. Activity levels in the ingesta are significantly higher in the fall than in the spring. Hypothetical dose estimates to man were calculated on the basis of liver or muscle from animals that contained peak radionuclide levels. The highest postulated dose was 8.6 millirems for tritium in tissues from a mule deer. The movements of 17 mule deer were monitored on a weekly basis.During the winter months, all deer left their summer range on the mesas of the Nevada Test Site and migrated 40 to 60 kilometers south and west. A statistical estimate was made of the deer population in selected areas utilizing the marked deer as a basis for this estimate. No gross or microscopic lesions were found in necropsied animals that could be directly attributed to the effects of ionizing radiation