The National Audubon Field Guide describes Baboons as very large monkeys with long, equally developed limbs and shorter tails than their forest-dwelling cousins. Baboons spend most of their days foraging on the ground; at night they roost in trees or on cliffs. These dog-headed monkeys have short fingers, but the fully opposable thumb and forefinger provide a good precision grip. Females have colorful sexual swellings that balloon grotesquely during full estrus. Males are up to twice the size of females, powerfully built with long fangs. Baboons are highly gregarious, living in large troops that contain a number of adult males. All males emigrate at least once to seek their reproductive fortunes in another troop. As baboons are non-territorial, the ranges of different troops overlap widely; however, usually different troops are mutually antagonistic.