The black howler (Alouatta caraya) or black-and-gold howler, is among the largest New World monkeys and a member of the Alouatta genus. The black howler is distributed in areas of South America such as Paraguay, southern Brazil, eastern Bolivia, northern Argentina, and Uruguay. This species is sexually dimorphic, with adult males having entirely black fur and adult females and babies of both sexes having an overall golden colouring; which emphasizes black-and-gold in the name. The IUCN Red List has classed the black howler as Near Threatened as a result of a recent population reduction due to a variety of human-caused factors. Taxonomy The black howler is one of nine species of the Alouatta genus that have been identified and is in the Atelidae family. Because of this species' sexual dimorphism, the taxon for the black howler has been distinguished. Alouatta caraya Alouatta pigra Alouatta seniculus Alouatta arctoidea Alouatta sara Alouatta macconnelli Alouatta guariba Alouatta belzebul Alouatta palliata Description Physical appearance Black howlers are sexually dimorphic, the male and the female are distinguishable due to the difference in their fur coatings. As the male black howler grows older, his fur will change from a golden colour to a complete black fur coat. The female, as well as infants of both sexes, have fur of a golden tone. Female howlers are lighter in weight than males, who are 47% heavier. Males' weight ranges from 6 kg to 7.7 kg. The hyoid bone volume of male black howlers is larger than that of female black howlers; it is assumed that this bone serves as a chamber for their howls. They have prehensile tails with a bare patch of skin on the underside, making them versatile climbers and allowing them to comfortably stay around in the canopy of trees. Behaviour and diet Black howlers share many behaviors with other howler monkeys. They are recognized for their 'howl', a powerful vocalization. A howler's 'howl' is one of the primates' strongest vocalizations, and it may be heard up to two kilometers away. The vocalizations of Black howlers have been studied in Brazil, and they prefer to employ the majority of their vocal activity around dawn. Howling is used as a behavioural strategy for displaying territory and regulating inter-group distance. This species is mostly arboreal, rarely coming down to the ground. They are also one of the least active groups of primates, as they are diurnal and