Resumen

While predominantly arboreal, spider monkeys of various species sometimes have been observed descending to the ground. Individuals of Ateles chamek have been reported to access some kind of food resources (rotten wood or salt licks) on the ground. We describe the terrestrial behavior of an adult female Ateles chamek (Peruvian spider monkey) on a sandy bank of the Pinquén River, Manu, Peru. This behavior lasted several minutes, with sequences of walking on four legs, pausing, and standing upright on the hind legs. The probability that she was a pet is very low due to the location being remote from population centers. The possibility of the individual looking for water to drink directly from the river is not discarded but due to the low water level and short distance between the two banks of the river, it is believed that this solitary adult female (migrant sex in the species) had intentions to cross the river, and that our presence ultimately influenced her decision not to cross.