hind legs, but the spines lack barbs. Spiny rats, like
some lizards, have tails that can break off with a minor
tug, an adaptation that permits escape from a predator,
though with the cost of a tail. Spiny rats are found on
the forest floor but the closely related tree rats (Echimys
spp.) are arboreal.
Trees provide habitat for approximately 20 species
of Neotropical tree squirrels (mostly in the genus
Sciurus), which are similar in appearance to North
American tree squirrels (also Sciurus). The ancestors
of these animals ventured southward during the great
faunal interchange of the Pleistocene (chapter 8).
Some Neotropical sciurids are reddish, including the
Amazonian Red- tailed Squirrel (S. granatensis). One
particularly striking species is the Central American
Variegated Squirrel (S. variegatoides), which ranges in
color from white with a black back, to reddish black, to
blackish gray, depending upon range. To my eyes, the
most wonderful of the lot is the diminutive Amazon
Dwarf Squirrel (Microsciurus flaviventer), an adorable
and hyperactive little brownish rodent with a thin,
straight tail and big, curious eyes. This largely solitary
creature, undersize for a squirrel, lives most of its life
in the canopy.
Finally, there is a group of rodents collectively called
spiny pocket mice (genera Heteromys and Liomys).
These little mice look very much like North American
deer mice and white- footed mice (genus Peromyscus).
They feed mostly on seeds.
Collared and White- lipped Peccaries
Peccaries are members of the huge even- toed ungulate
order, the Artiodactyla. They closely resemble wild
pigs but are in their own family, the Tayassuidae. They
differ from pigs in that their upper canine teeth are
extremely sharp and point straight downward, whereas
in pigs these teeth curve outward as tusks. Peccaries
also have a dorsal scent gland, located toward the
posterior of their backs. This gland exits through a
large and conspicuous opening that was once mistaken
for the animal’s navel! The secretion from the gland is
quite musky, and the animals rub their faces vigorously
against one another’s scent gland as a means of
recognition and solidification of the herd. Peccaries are
highly social animals and are rarely seen singly.
The most common, and also the smaller, of the two
peccary species is the 22.7– 29.5 kg (50– 65 lb) Collared
Peccary (Pecari tajacu; plate 16- 29). This species is
Plate 16- 30. White- lipped Peccaries are greater in body size
than Collared Peccaries. They form larger herds and have
a reputation for being aggressive on occasion. Photo by
Andrew Whittaker.Plate 16- 29. Collared Peccaries remain in family groups and
are usually not aggressive. Photo by Andrew Whittaker.Plate 16- 31. This White- lipped Peccary is exhibiting aggressive
behavior, staring directly ahead, with its bristly upper back fur
erect. It’s time to move away. Photo by Andrew Whittaker.332 chapter 16 from monkeys to tarantulas: endless eccentricities