National Geographic : 1979 Feb
pouch dweller. In others, the dormant em bryo automatically awakens after the nor mal maturation of the preceding one. Boss Roo Brooks No Interference Among many species, kangaroo society appears to be a rather casual affair, with in dividuals drifting in and out of small groups without any long-term commitments. Thus, the old boomer who has battled his way to boss roo finds himself with an ever changing following-which doesn't reduce his feroc ity, however, should another male decide to challenge his authority. Small groups, or mobs, can collect into sizable ones, usually when they gravitate to the same sources of food and water. But even in places where the big roos are plenti ful, they may escape detection. Nocturnal by nature, they prefer to bed down by day, concealed by tall grasses or the dappled shade of casuarina and eucalyptus trees. Some kangaroos reach the ripe old age of 20, but normal life span in the wild seldom exceeds 7 years. Wedge-tailed eagles, py thons, and goanna lizards pick off small ones; man and dingo dogs kill adults. But the most devastating enemy is drought.