Geoscience Reference
In-Depth Information
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Gliders of the Forest
On the island of Borneo, the tropical rainforest
hosts a variety of animals that have a unique
adaptation to life in the trees. Snakes, lizards,
frogs, giant squirrels, and colugos all glide
through the forest canopy trees. These forests
hold more than 30 types of gliding animals,
more than any other location on Earth. Most
gliders are nocturnal and have cryptic coloring
that lets them blend into the canopy. They
have evolved different strategies for gliding
success such as skin flaps, webbed feet, and
flattened bodies.
Why so many gliders? The structure of rain-
forest in Borneo is different from other rainfor-
ests in that the many large emergent trees are
clumped together. The upper canopy is discon-
tinuous and has fewer climbing vines and
fewer connections between the trees that
serve as arboreal highways. Gliding is an effi-
cient mode of travel in these circumstances.
Furthermore, since most of the trees in the
rainforest of Borneo are dipterocarps that fruit
infrequently, food can be sparse. Animals must
be able to move quickly and efficiently through
the forest to find food. By gliding, these ani-
mals do not have to make the long trip up and
down the tree trunks. They can remain in the
canopy out of the reach of most predators. Bor-
neo's isolation over time has allowed many ani-
mals to develop this unique adaptation. If one
cannot fly, surely gliding is the next best thing.
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that occupy similar niches as placental mammals
in the west. Bats are abundant in both areas.
Mammals
The different mammal families in the West
Malesia subregion of Asian-Pacific rainforest are
listed in Table 3.4. The Asian rainforest, like the
African forest, has pangolins, but not the arboreal
forms found in Africa. All Asian pangolins are
terrestrial. They rest in burrows during the day
and search the forest floor at night for ants and
termites. The two species found in the Asian-Pa-
cific rainforest are the Malayan pangolin and In-
dian pangolin.
Tree shrews are neither true shrews nor arbo-
real. They have been put in their own taxonomic
order, Scandentia. Tree shrews probably evolved
from insectivores, although some argue they
descended from primitive primates. Resembling
ground squirrels, they have bushy tails and nar-
row snouts. Tree shrews have the highest brain-
to-body-mass ratio of any animal, even higher
than humans. They are commonly found on the
forest floor, where by day they feed on fruit,
arthropods, and seeds. A few species live in the
tropical rainforests in West Malesia; others
inhabit the tropical seasonal forests. They are
absent from New Guinea and Australia.
The Asian-Pacific region ranks second to the
Neotropics in terms of diversity of bats. Bats are
the most numerous and speciose mammal of this
entire rainforest region. Both Megachiroptera and
Microchiroptera are represented by many species.
The largest are called flying foxes (because of their
fox-like heads) and are fruit eaters. Elongated fin-
gers support their 4 ft (1.2 m) wingspan. Flying foxes inhabit forest and swamps.
Most roost on the branches of emergent trees. At dusk, they fly into the forest can-
opy to feed on ripe fruit.
Other Old World fruit bats range in size from 0.5 oz-3 lbs (15-1,500 g). They
are most active at night, but have been seen flying during the day. They often make
long flights moving out of an area when fruit is no longer available. The larger fruit
bats are gregarious and roost in large groups, while the smaller fruit bats are soli-
tary. Many of them locate food by smell. Fruit bats play an important part in
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