Pronghorn antelope herd, pronghorn, pronghorns, pronghorn antelopes, pronghorn antelope, antelope, Antiloapra americana, mammal, mammals, animals, ungulates, wildlife, animal, fauna, ungulate, north america, Montana, Western U.S., warm-blooded, wild, vertebrate, herbivore, grasslands, grassland, plains, prairie, herd, group, warning, warn, sign, signal, signaling, behavior, signalling, white rump hairs, rump, horizontal, photo, photos, photograph, photographs, image, images, picture, pictures, stock, of, agency, leesonphoto