The positional behavior of pygmy marmosets (Cebuella pygmaea) in northwestern Bolivia.

Pygmy marmosets are distinctive given their diminutive body size, their year-round reliance upon exudates, and their use of morphologically adapted tegulae to engage in a high degree of claw-clinging behaviors associated with exudate exploitation. This project examined the positional behavior and habitat preferences of one group of pygmy marmosets in a secondary forest within the Department of Pando, northwestern Bolivia. Results from this study indicate that pygmy marmosets primarily use claw-clinging during feeding (89.6%) with preferential use of large vertical trunks. Claw-clinging was also the dominant postural mode during exudate foraging (43.1%) with preferential use of large vertical trunks. Quadrupedalism was the dominant locomotor mode during travel (55.7%) with preferential use of bamboo and medium-sized substrates. These results support previous notions that claw-climbing is a solution to overcome the constraints of small body size while suggesting that quadrupedalism is a habitat-dependent locomotor mode.