Geoscience Reference
In-Depth Information
any given feeding. Large size is also effective in reducing the risk of predation by
limiting the types of predators that can attack an individual bird. Lowered preda-
tion risk has allowed fruit-eating birds to evolve striking color patterns. These col-
ors probably are used to attract mates, as well as to signal potential rivals. They
may also camouflage the bird amid the brightly colored flowers and fruits in the
canopy.
Turacos are the only bird family endemic to Africa. All 23 species are frugivores,
specializing particularly on figs. They also consume leaves, buds, and flowers. They
usually feed in mixed flocks with other birds such as green pigeons, hornbills, and
barbets. Turacos have small rounded wings and long tails, which make them weak
fliers; but their strong legs allow them to move freely within the forest trees. Most tur-
acos are brightly colored with crested heads (see Plate XI). The largest species is the
Great Blue Turaco, which measures 30 in (750 mm) in length.
Another brightly colored frugivore in the African rainforest is the hornbill. The
hornbill bears a close resemblance to the toucan of the Neotropics, but the two are
not related. Hornbills have large heavy bills with bright coloration used to reach fruit
at some distance from their perch. The bills are also used in display, to build nests,
and for defense. Besides fruit, some hornbills eat insects and other small animals.
The African rainforest has few parrot species, probably due to the large number
of squirrels and other rodents that take up typical parrot roles as fruit and seed eat-
ers. The African Gray Parrot is a popular bird in the international pet trade because
of its incredible vocal abilities and the speed with which it learns to mimic sounds.
Few parrots occur in Madagascar as well.
The other brilliantly colored birds of the African rainforest are nectar feeders.
Year-round availability of flowers and nectar provides them with a constant food
supply. Sunbirds are the main flower-visiting birds in the African rainforest. They
are small and brightly colored, with feathers that can sometimes have a metallic
sheen. Many have downward curved beaks and a long tubular tongue that is split
in half at the tip. Sunbirds have strong legs and sharp claws to aid in climbing rain-
forest trees. They usually take nectar while perched, and many plants pollinated by
sunbirds have adapted to accommodate their pollinators by producing flowers on
their branches in easy reach of perching birds. Africa's great variety of sunbirds
occupies similar niches and is similar in appearance to the hummingbirds of the
Neotropics, but they are not related.
Insectivorous birds in the tropical rainforest dominate in terms of numbers of
both species and individuals. The majority are the small brown birds that forage
through the lower canopy and understory, searching for insects and small arthro-
pods on twigs, branches, trunks, vines, and leaves. They often travel in mixed
flocks that may include Old World Warblers, flycatchers, babblers, drongos, white
eyes, and woodpeckers. Frequently, sunbirds and weavers join the group. Some in-
sectivorous birds gather around ant swarms like antbirds of the Neotropics.
Far fewer ground-dwelling birds live in the rainforests of Africa than in both
the Neotropical and Asian-Pacific regions. No large ones inhabit the region. The
