Studies on Peculiar Distribution Pattern of Callimico

Abstract

The geographical distribution of Callimico is between the Rio Caqueta in southern Colombia as its northern limit and the Rio Orthon and Rio Manuripi in northern Bolivia as its southern limit. Being small in numbers in this range, it lives in groups which maintain long distances between each other. The author considers such a pattern of distribution as peculiar to this species of monkey. Callimico inhabits “shabby” forest, such as second-growth wood, bamboo forest, and forest whose canopy is discontinuous, so that scrub grows well, and those in further inland areas. The ecological and behavioral peculiarities of Callimico appear to represent adaptations to life in such “shabby” forests. The habitat of Cebuella, whose distribution covers the same range as Callimico, is also the “shabby” forests, but is located at the forest edge. Callimico and Cebuella are thus segregated between the inland areas and forest edge, respectively. Five species of Saguinus are also found in the same range, of which S. fuscicollis occurs sympatrically with any one of the other four species. Saguinus tends to inhabit rather the mature forest but often utilizes the “shabby” forest also. It may represent a good competitor of Callimico. Examination of the relationships between Callimico and callitrichid monkeys from the phylogenetic evolutionary viewpoint indicates that Callimico came to adopt its present pattern of distribution as a result mainly of decrease in “shabby” forest in the upper Amazon basin and of competitive relationships between Callimico and Saguinus fuscicollis which enlarged southward its inhabited range from the north, where it may originally have made speciation.