Perezosa, Unau (Spanish)
Choloepus hoffmanni
Class:
Order:
Family:
Genus:
Mammalia
Pilosa
Bradypodidae
Choloepus
Distribution
Central to South America
Northern distribution
includes Costa Rica.
Habitat
Lowland and upland
tropical forests, in both
deciduous and mixeddeciduous forests.
Food
Arboreal herbivore.
Reproduction
When a female is ready to
mate she calls out, quite
loudly, to attract a mate.
Any males in the area will
move slowly towards her.
Mating takes place while
hanging from a branch by
their forelimbs, face to face.
The range of the two-toed sloth is Central America and
northern South America, including portions of Peru and Brazil.
Two species of sloth belong in this genus, Choloepus hoffmanni and
Choloepus didactylus. Hoffman’s two-toed sloth has two disjunct
populations. The northern population ranges from Nicaragua
south into western Venezuela. The southern population is found
in parts of Peru, Brazil and Bolivia. Choloepus didactylus is referred
to as the southern two-toed sloth, inhabiting several countries in
the northern part of South America.
In Costa Rica this species ranges from sea level to elevations of
3,300 m. In Central America it is found in evergreen and semideciduous tropical moist forests as well as secondary forests. It
is rare or absent in lowland dry forests.
They feed primarily on vegetation, including leaves, berries,
buds, small twigs and fruit. They can consume fairly tough
vegetation. They may derive additional nutrition by ingesting the
algae growing on their fur. Water is obtained from moist leaves
and dew drops.
If two males approach the female at the same time they will
wrestle with each other, hanging upside down by their hind
limbs and swinging at each other with their forelimbs.
The gestation period is 11½ months, longer than Choloepus
didactylus, at 6 months. She gives birth while hanging upside
down. The baby emerges head first. It already has tiny claws
which it uses to pull itself onto the mother’s belly, assisting in its
own birth. The newborn is 25 cm long and weighs 300 to 400 g.
Single births occur every 14 to 16 months.
Development
The baby clings to its
mother’s belly, right side
up, using its tiny claws to
hold on to her fur. It
spends all its time feeding
and sleeping. It stays with
her for a few weeks nursing
regularly as she climbs,
feeds or rests.
Characteristics
The pelage has two types of
hairs, long guard hairs and
short under fur. The limbs
are relatively long. The
forelimbs have two digits
tightly bound with skin.
The hind feet have three
digits. All four limbs have
long hook-like claws. The
tail is absent or vestigial.
Adaptations
Fur curves from the
stomach to the back
allowing rain to run off.
A sloth’s temperature can
vary by several degrees,
adjusting to ambient
temperatures, thus
conserving energy.
They are good swimmers,
using a breast-stroke type
motion.
Status/Threats
It has a wide distribution
and occurs in a number of
protected areas.
Sightings at Caño Palma
General compound area.
Young sloth’s first hang upside down at 20 to 25 days after
birth. After several weeks the baby begins to nibble on leaves,
reaching for whatever vegetation is within its grasp. They begin
to feed away from mother at about five months of age. Young
continue to associate with their mothers for at least two years
after birth. Females reach sexual maturity at three years of age;
males reach this at between four and five years. Females
associate in groups, while males are solitary. Average adult
weight is 5.7 kg. Head and body length is from 540 to 700 mm.
Sloths are divided into two families based on the number of toes
on their front feet. Two-toed sloths are larger than their threetoed cousins and are a little more active. They have fewer
cervical vertebrae, six to seven; three-toed sloths have nine.
They have bigger eyes and longer hair. Hair colour is tan to
grayish brown, the face is paler. Front and back legs are more
or less equal in length. They sleep with the head placed between
the forelegs. All four feet are often placed so close together the
sloth looks like a bunch of dried leaves. They are very difficult to
spot in this position. Because of their upside-down lifestyle
many of their organs are in different positions from other
mammals. They are mostly silent but can cry out or make a
hissing sound. When on the move they use a hand-over-hand
motion.
The hair is structurally unique among mammals; each strand has
grooves which collect algae, giving the sloth a greenish tint thus
camouflaging it from predators. They are generally nocturnal.
Teeth are peg like. Compensating for lack of sharp teeth the lips
are hardened and capable of sheering off leaves and twigs. The
stomach is complex, increasing the efficiency of digesting
vegetation. Muscle mass is much less than other animals of
similar size, the sloth therefore weighs less, allowing it to climb
along thin branches in search of food. The muscles in its
shoulders, neck and front legs are quite strong. To reduce the
risk of being attacked the sloth only descends to the forest floor
to defecate about once a week.
The IUCN lists these as of Least Concern. However, because of
ongoing deforestation, the northern population could potentially
be assessed as Near Threatened.
On a site-monitoring trip, board members of COTERC were
fortunate to see two-toed and three-toed sloths. Both sightings
were of mothers carrying babies on their chests. Two-toed
sloths are not uncommon around the station area.
References
Meritt, M. & members of the Edentate Specialist Group 2006. Choloepus hoffmanni. In: IUCN 2007. 2007 IUCN Red List of Threatened
Species. <www.iucnredlist.org>. Downloaded on 03 May 2008.
Bach, Julie. Sloths. Mankato, Minnesota: Creative Education, 1999.
Canadian Organization for Tropical Education and Rainforest Conservation
www.coterc.org