Brachyteles arachnoides

In 1998, Wildlife Preservation Canada partnered with Instituto de Pesquisas Ecologicas (IPE) project leader for Muriqui recovery.  The initial two-year project consisted of basic field research including a census and the study of population distribution, detailed habitat requirements and mortality factors.  The project focused on newly discovered populations of muriqui on private lands in the Serra de Mantiqueira region of Minas Gerais and Sao Paulo states.  The objective of the first phase of the study for IPE, local landowners, and, if appropriate, IBAMA, the national agency responsible for wildlife and the environment, was to develop a conservation plan.  The study provided field training experience for graduate biologists working under project leader Dr. Claudio Padua.  In addition to the scientific work, the project focused on local education programs on the muriqui as a symbol for conservation of local habitat.


Weighing 15 kg at maturity and measuring 80 cm from head to tail, this herbivorous species is the largest New World primate and one of the most endangered primates in the world.  Muriquis have a strong prehensile tail, which, coupled with their long arms, makes them nimble climbers and arboreal acrobats.

Their social system is thought to be matriarchal.  When females mature, they move to neighbouring groups.  In keeping with the species’ docile nature, a female in estrus mates with all her suitors. Instead of competing aggressively with one another, males bond closely which generates strong group cohesion and calm social relations.  The young are born helpless and mature slowly, so adults invest much time raising each offspring.


Muriquis were once found throughout the Atlantic forest of southern Brazil.  Despite rampant habitat destruction, Muriquis survive in several isolated patches of both primary and secondary forests between 600 and 1800 m (1969 and 5906 ft) above sea level and exhibit flexibility in their habitat requirements.

Distribution and Population Size

Muriquis can be found in isolated pockets of mountainous forest in southern Brazil in the states of Espirito Santo, Rio de Janeiro, Sao Paulo, Parana, and Minas Gerais.  They are distinctly separated into northern and southern regions, with the northern region including populations in the states of Minas Gerais, Espírito Santo, and Bahia, and the southern population existing in the states of southern Minas Gerais, southern Rio de Janeiro, and São Paulo.  The populations are separated not only by human development and lack of contiguous forest, but also by riverine barriers such as the Rio Grande, the Rio Paraiba do Sul, or the Serra da Mantiqueira.  The current Muriqui population is estimated at 2,000 in isolated pockets, a dramatic drop from original levels of approximately 400,000.

Threats to Survival

There are two main threats to survival.  One is habitat loss – an estimated 5% of the original Atlantic forest cover remains, with only 1% in pristine condition.  The other is illegal hunting – the Muriqui’s docile nature and large size make it an easy and attractive target.