Before 1918, approximately 57% of the wolves in the New Mexico and Arizona region were male, and 43% were female. However, cattle ranchers in this area have made a determined effort to exterminate wolves. From 1918 to the present, approximately 71% of wolves in the region are male, and 29% are female. Biologists suspect that male wolves are more likely than females to return to an area where the population has been greatly reduced.