CONSERVATION BIOLOGY OF THE GENUS ALOUATTA

As assessed by the IUCN Mace-Lande system, seven (35%) of the 20 Aloua tta species and subspecies with adequate data are classified as ''thre atened,'' i.e., critically endangered, endangered, or vulnerable (Ryla nds et al, 1995). This percentage is much lower than the 75 to 100% th reatened taxa for, the other large-bodied genera: Ateles, Lagothrix, a nd Brachyteles. Only 5 of the 16 Neotropical genera have lower percent ages of threatened taxa than that of Alouatta: Cebuella, Pithecia, Sag uinus, Saimiri, and Cebus The threatened howler taxa occupy small dist ributions in areas of forest fragmentation. In general, populations ar e most affected by major habitat disturbance, such as total deforestat ion and flooding from dam construction, and by human hunters. Facilita ted by their ability to exploit folivorous diets in small home ranges, howlers can tolerate considerable habitat fragmentation but not the i ncreased exposure to hunting that may accompany it. Howlers seem parti cularly vulnerable to yellow fever and bot fly parasitism. Although th e former threat may decrease by increasing fragmentation of the habita t, other sorts of parasitism may ino ease in disturbed habitats. The L ow genetic variability of the Central American howlers suggests a resi stance to inbreeding depression potentially experienced during populat ion bottlenecks. Greater between-population variability may still exis t. Although howlers are not readily bred in captivity, they respond we ll to translocation. Translocation has been successfully achieved for greater than or equal to 4 howler species and is a viable option for i ntroducing new genetic variability into population fragments and repop ulating areas from which howlers are extinct. Their pattern of bisexua l dispersal facilitates colonization of regenerating habitats, and in suitable, protected habitats they have shown the capacity for strong p opulation recovery.