Female and male howler monkeys

The black howler is a species of howler monkey, a large New World monkey, from northeastern Argentina, eastern Bolivia, eastern and southern Brazil, and Paraguay. Together with the brown howler, it is the southernmost member of the "Alouatta" genus. Only the adult male is black; adult females and juveniles of both genders are overall whitish to yellowish-buff. However, variations occur even among the adult males; some have patches of reddish-brown or buff fur.