By Lisa DeBruine
Geographic Range
Panama, Bolivia, Brazil, Colombia, Ecuador and Peru.
Biogeographic Regions:
neotropical 
(native ).
Habitat
Like most callitrichids, saddle-backed tamarins prefer secondary forests and edge habitats, but they are also found in primary forests. Their home range, sized between 25 and 100 ha, often includes many types of habitat. S. fuscicollis has a day range length of approximately 1,500 m.
Terrestrial Biomes:
rainforest .
Physical Description
(1.23 oz)
Saddle-backed tamarins are generally a rust color with a distinctive black head and white muzzle. They have very little sexual dimorphism in mass. Like all tamarins, they have a long, but not prehensile, tail. They have clawed digits (except for the hallux) and no opposable thumb.
Some key physical features:
endothermic ; bilateral symmetry .
Reproduction
The interbirth interval is about 12 months, although captive tamarins are capable of reproducing twice each year
The majority of social groupings consist of one female, more than one male, and young. This polyandrous organization probably results from the unique reproductive system of tamarins. In groups with one female and two males, both males usually mate with the female and each cares for one of the resulting offspring. Juvenile saddle-backed tamarins also engage in helping behavior, carrying and feeding the infants. These behaviors help the mother to cope with the demands of lactation, which are quite high.
Mating systems:
polyandrous ; cooperative breeder .
The reproductive system is the most interesting aspect of tamarin biology. Saddle-backed tamarins come into sexual maturity at the age of 23 months. Their gestation period is 140-150 days and the interbirth interval is about 12 months, although captive tamarins are capable of reproducing twice each year. All this is unextraordinary. The amazing part is the size and number of offspring. The majority of births are twins whose total weight is almost one-quarter that of the mother's. It is thought that this fact is a major contributing factor to the tamarin's polyandrous social organization. Or it is possible that polyandrous care-taking of infants led to the evolution of twin births and exceptionally high birth weights.
Key reproductive features:
iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous .
Females have offspring whose total weight is almost one-quarter of their own body weight. Males help care for their offspring.
Parental investment:
pre-fertilization (provisioning, protecting: female); pre-hatching/birth (provisioning: female, protecting: female); pre-weaning/fledging (provisioning: female, protecting: male, female).
Behavior
The general behavior of S. fuscicollis can be summarized by this daily time budget: 16-17% feeding on plant material, 16% foraging for insects, 44% resting, and 20-21% travelling. The most studied aspect of saddle backed tamarin behavior is the social organization. S. fuscicollis tend to live in groups of three to ten individuals, including infants.
Food Habits
Saddle-backed tamarins are omnivores, mostly eating insects, fruit, nectar, and exudates (tree sap and gum). Tamarins may eat exudate for its high calcium content, which compensates for the low calcium content of fruits and insects. They spend most of their foraging time searching for large (2-5 cm long) insects hidden in trees.
Primary Diet:
omnivore .
Animal Foods:
insects.
Plant Foods:
fruit; nectar; sap or other plant fluids.
Economic Importance for Humans: Negative
There are no negative effects of saddle-backed tamarins.
Economic Importance for Humans: Positive
Saddle-backed tamarins are important members of the ecosystems in which they live. They help with seed dispersal of the fruits they eat and are important prey animals for their predators. They may contribute to ecotourism activities where they occur.
Conservation Status
Loss of habitat due to deforestation would be the main threat to the saddle-backed tamarins.
Contributors
Lisa DeBruine (author), University of Michigan.
Phil Myers (editor), Museum of Zoology, University of Michigan.
