The Pygmy Marmosets of Ecuador

With wiry hair framing its tiny face, the pygmy marmoset of Ecuador is sometimes referred to as leoncity (little lion), or mono de bolsillo (pocket monkey), being a reference to its diminutive size. Thriving on a diet of tree gum, insects, arachnids and even small lizards, pygmy marmosets (Cebuella pygmaea) are found in the rainforests of eastern Ecuador, particularly near rivers, as well as in parts of Colombia, Peru and Bolivia.

As the smallest true monkey in the world, the pygmy marmoset walks on all fours, weighs between 120 and 140 grams and is between 14 to 16 centimeters in length, excluding its black-ringed tail which measures between 15 and 20 centimeters. They are resourceful in finding their favored food source and gnaw holes in the bark of trees with their sharp lower incisors, resulting in the tree oozing gum for the eager little creatures to consume. It is quite common to find brown-mantled tamarins living in the same area as the marmosets, where they are known to raid the gum holes gnawed by the tiny monkeys. Living in family groups of between one and two adult males and adult females along with a breeding female and her offspring, once the group has exhausted the gum supply in an area, they move to a new area.

The family group has a complex set of sounds they use for communication, and visitors to the rainforests of eastern Ecuador are likely to hear the sharp whistle and clicking sounds they make to warn family members of danger. A series of fast notes, dubbed the “J-call” by researchers, made by the marmosets is thought to serve as a reassuring sound promoting cohesion among the group and warding off rival groups. An individual marmoset will always recognize its own group’s call as opposed to the similar call made by members of another group. The J-call is used to communicate over fairly short distances, whereas a low frequency call is used for long distances, as this frequency travels further in the heavy growth of the forest. The development of speech abilities in infant marmosets has been compared with that of human babies, as it babbles before it learns the communication skills of adulthood. All the members of the group care for the infants, including older siblings.

Although pygmy marmosets are extremely cute, they do not necessarily make good pets. As social animals, they are happiest in a group of their own kind and can be quite aggressive and quick to bite with those sharp teeth that were designed to bite through the bark of trees in the wild, where it is best for them to remain.