spend up to 60-70% of the day resting or sleeping. Although the diet of the black howler is largely folivorous, it does not prevents the digestion of fruits, figs, mosses, bark, seeds, and flowers. Eating leaves may appear to be unfeasible for other primates, as it lacks nourishment and energy; however, howlers have developed a complicated digestive system that allows them to digest leaves quickly and have strong molar teeth to help chew mature leaves. Group composition Group composition has a large varied range in population density and social organization when focusing on black howler monkeys. Due to minimal human influence along the Paraná River in Brazil, for example, the woods remain well conserved, which results in larger densities of black howlers. Usually, howler monkeys have a single dominant male, with multiple adult females and babies in smaller groups. In larger groups, the howler monkeys' group composition can vary. In a 2009 study by Lucas M. Aguiar, Gabriela Ludwig, and Fernando C. Passos, in the Upper Paraná River of southern Brazil, the black and gold howler groups size was around 6 to 18 individuals. There were 11 groups total in Paraná River and groups were all multi-male; the females were outnumbered. The range for how many black howler monkeys in terms of age and sex in individual groups were represented. The study concluded that in these individual groups, it was likely to see a range of male adult black howlers from two to five, three to seven adult females, zero to four adolescents, and zero to three babies. Mating Mating behaviour and patterns of the black howlers have been identified. A study by Martin M. Kawoleski and Paul A. Garber in 2010 examined the promiscuity of black howler females along the Paraná River in Argentina using a scan sampling technique. According to the findings, sexual solicitation of female mate choice occurred when a female actively pursued a particular male by grooming, touching, and following him, and displaying a specific posture to get the male to approach them. During fertile and nonfertile phases, black howler monkey species' females mate with many adult males. Female black and gold howlers have been shown to conceive within a 3–4 day ovulatory phase, according to previous research. It is still unknown if male howlers can discriminate ovulatory phases in females using visual or smell cues. The adult female black howlers tend to give birth within