Male intergroup mobility in a wild population of the Barbary macaque (Macaca sylvanus), Ghomaran rif mountains, Morocco.

In this two-year study of a Barbary macaque population (n = 162) in the Ghomaran region of Morocco, 13 cases of males separated from their assumed natal groups were observed (nine visits of nonresident males to groups, two males isolated from groups as much as one day and one night, and two sets of snow tracks indicating males travel +7 km as isolates). Males left their assumed natal groups primarily in the mating season (12 cases), focused their interactions on estrous females of other groups, and were observed to copulate with these females in two cases. All males leaving their assumed natal groups were estimated to be between 5 and 8 years of age, with one exception (+ 15 years). It could not be determined whether males younger than 5 years moved between groups, or whether any males made permanent intergroup transfers. Regardless, the data from this study indicate that male intergroup mobility (and intergroup gene flow) was higher than has been previously assumed for this species. A prior theory that Barbary macaque groups are highly inbred, and that this is causally related to the evolution of male-infant care in this species, is not supported by the data of this study.