Maranhão Red-Handed Howler

• Common Name: Maranhão Red-handed Howler
• Taxonomy Classification Year: 1912
• Monkey Size: 40.0 to 91.5 cm (15.75 to 36.02 in)
• Skin Color(s): Black to deep reddish or yellowish
• Habitat: Forest, rainforest
• Diet: Herbivorous
• Native Countries: Brazil

The Maranhão red-handed howler^[1] (Alouatta ululata) is native to forests (e. g., Babaçu forests) in the northeastern Brazilian states of Piauí, Maranhão, and Ceará. Red-handed howler monkeys are among the least studied species of all howler monkeys.

• As their common name suggests, Maranhão red-handed howler monkeys have reddish hands, although some may appear more yellow.
• The coat varies from black to dark reddish or yellowish. Their fur is coarse, and their face and the distal part of their prehensile tail are bare and black (applies to all Alouatta species).
• These endangered howler monkeys are generally the largest monkeys in the New World. In this species, the tail length varies from 58.5 to 91.5 cm.
• Maranhão red-handed howler monkeys are sexually dimorphic in size;
• The male mass ranges between 6.5 and 8.0 kg, while the female mass ranges between 4.85 and 6.2 kg. Lengthwise, males range from 56.5 to 63.0 cm and females from 40.0 to 65 cm.
• However, there is some disagreement in the literature about these numbers, with another source stating a length range of 55.9 to 91.5 cm.

• Maranhão red-handed howler monkeys are diurnal, although they spend most of the day (up to 80%) sleeping on branches with members of their troop.
• When awake, these howler monkeys move through the trees for food using quadrupedal locomotion.
• These howler monkeys typically live in small social groups of 5 to 14 individuals.
• The best-known behavioral trait of the Maranhão red-handed howler monkeys is their loud vocal calls or howling sessions.
• They have a full trichromatic vision and perceive the world using the full spectrum of visible light.