Date of Award
College of Arts and Sciences
Master of Science
Dr. Janice Chism
Dr. William Rogers
Dr. Matthew Heard
Monk Saki, Equatorial Saki, Pithecia, Habitat Partitioning, Niche Theory
Researchers previously reporting equatorial and monk sakis (Pithecia aequatorialis and P. monachus) occurring sympatrically north of the Amazon River in Peru raised the question of whether the two species were syntopic or separated by habitat. I encountered both species of saki south of the Amazon in Peru in the Área de Conservación Regional Comunal Tamshiyacu Tahuayo (ACRCTT). Initial observations and local lore suggested that in this area equatorial sakis occur predominantly in flooded forests and monk sakis in terra firme. I conducted a six-week survey (324 hours effort, a minimum of 18 groups observed) to test this hypothesis, collecting data on location and habitat preference of the two species using both terrestrial line transect surveys and canoe-based sampling. My findings indicate that the two species are syntopic, with both species occurring in igapó forest adjacent to rivers, but only equatorial sakis observed in terra firme forest. These results indicate that if the two species segregate by habitat, it is based on features other than a simple dichotomy between igapó and terra firme forest. In my study area, equatorial sakis significantly outnumber monk sakis (x2=10.889, d.f.=1, p=0.0010), despite previous surveys that only reported monk sakis in the reserve. My census data also confirmed the presence of atypically colored adult females in some equatorial saki groups, supporting earlier suggestions that the two species may be hybridizing.
Jackson, Richard L., "Habitat Stratification of Pithecia Species in the Área de Conservación Regional Comunal Tamshiyacu Tahuayo in the Northeastern Peruvian Amazon" (2016). Graduate Theses. 32.