The New Neotropical Companion

and rest, often frequenting bamboo thickets. Titis are

known for their dawn chorus, a loud, ringing duet

performed by pairs. They are confined to Amazonia.

Squirrel monkeys (genus Saimiri) are widely

spread in Amazonia and into Central America. The

Common Squirrel Monkey (S. sciureus; plate 16- 8)

is found throughout much of upper Amazonia. The

Central American Squirrel Monkey (S. oerstedii) is

an endangered species whose range is restricted to a

small area along the Pacific coast of Costa Rica and

Panama. Taxonomists are not in full agreement about

the systematics of this group.

A squirrel monkey does not resemble a squirrel. It

is a bit smaller than a capuchin, but its tail is equally

long, which gives it the appearance of a slender little

animal with an immensely long, thin, black- tipped tail.

The appealing eyes are dark, appearing quite large, and

surrounded by white “spectacles” that are contrasted

by a black nose and mouth. Ears are white. Body hair

is grayish, with rich rusty coloration on the back,

arms, and tail. The Central American species is rustier

in color than the species in South America. Squirrel

monkeys favor gallery forests, lowland rain forest, and

successional areas. They are usually obvious, as their

troops number anywhere from 20 to over 100 animals,

and they tend to be highly active among the trees’ outer

branches. They sometimes come around villages to

feed on bananas, plantains, and citrus. They eat many

kinds of fruits, as well as numerous insects.

Night monkeys, or douroucouli (Aotus spp.;

plates 16- 9– 10), are well named, as they are the only

genuinely nocturnal species. These smallish (0.9 kg/2

lb) monkeys with soft grayish- brown pelage range

from northern Argentina and Paraguay throughout

the Amazon Basin and north into Panama. One

look at the somewhat owl- like, rounded head, with

immense dark eyes surrounded by white fur, is enough

to discern the creature’s nocturnal way of life. Groups

of two to five night monkeys spend the daytime hours

cuddled together in a hollow tree or among dense vines

and other vegetation. At night they forage anywhere

from almost ground level to the top of the canopy.

They search for fruits, buds, insects, and occasionally

nestling birds. Their densely furred, black- tipped tails

are not prehensile. Their loud calls, heard at night, keep

the foraging troop together. Taxonomists do not agree

as to how many species there are, but up to 12 species

have been recognized, all very similar in appearance.

Uakaris (Cacajao spp.) are medium- size to large

monkeys of gallery forests along the upper Amazon.

Two species are currently recognized by IUCN. Cacajao

calvus, found in várzea forests, has two subspecies, the

Red Uakari, with long, thick reddish body hair, and the

White Uakari (plate 16- 11), with silvery- white body

Plate 16- 10. This Panamanian Night Monkey (Aotus zonalis)

clearly displays its thickly furred, non- prehensile tail. Photo by

Dennis Paulson.

Plate 16- 11. White Uakari (Cacajao calvus calvus). In 2008

this subspecies was listed by the IUCN (International Union

for Conservation of Nature) as vulnerable, due to hunting

pressure and habitat loss. Photo by John Kricher.

chapter 16 from monkeys to tarantulas: endless eccentricities 323