Ecological Islands within the Continent of Africa (Part 2-The Guinea and Ivory Coast)

The tropical forests of Guinea and Ivory Coast are separated from Central African tropical forests by a wide belt of savannah that stretches all the way to the Atlantic Ocean.  This zone of grassland is known as the Dahomey Gap.  The 2 regions of tropical forest share many of the same species, showing they were formerly connected, but they host different species as well–evidence they’ve been isolated for long enough that speciation occurred.  The Sahara Desert, located to the north of Guinea, has expanded during past climatic cycles, compressing this region of tropical forest into a smaller pocket.  Even today, sandstorms and desert winds deposit sand and spread fires in this region.  These factors exert a differing influence on this tropical forest than on Central African forests.  This may explain differences in floral and faunal composition between the 2 regions.

distribution map

 

 

 

 

 

 

 

 

 

 

 

 

 

The Dahomey Gap is a savannah that isolates the tropical forest of Guinea from the forests of Biafria to the southeast. This gap and rivers isolate chimpanzees into different subspecies.

Forest elephants (Loxodonta africana) had the greatest impact on the environment here until man nearly extirpated them.  Elephants were formerly so abundant they influenced the names of the nations.  Ivory Coast was named for the trade in elephant tusks, and the Guinea–a gold piece with an elephant image stamped on it–was used as money in the British Empire for centuries.  The decline in the elephant population caused a corresponding decline in white breasted guinea fowl (Agelastes meleagrides) numbers.  This species prefers open forest floors created by elephant trampling and foraging.  Without elephants, dense undergrowth covers the forest floor, a condition that favors a different species of guinea fowl–the crested (Guttera pucherani).

White-breasted Guineafowl (Agelastes meleagrides)

The white-breasted guinea fowl is in decline because it prefers open forest floors created by elephants which have been extirpated from many places within this region.

Over 140 species of mammals live in this region, including 11 species of primates.  There are 7 species of small forest antelopes known as duikers, 2 species of wild hogs, forest buffaloes, pygmy hippos, chimpanzees, colobus monkeys, Liberian mongoose, genets, and large leopards.  The jungle leopards grow larger than savannah leopards, probably because they don’t face competition from lions and are the king cat in this region.

When most people think of African wildlife, they don’t think of squirrels, but this region is home to 6 different species.  All African squirrel species originated from ground dwellers that invaded the continent 10 million years ago.  They later adapted to life in the trees.  The most primitive local species is the western palm squirrel (Epixarus ebii)–a large squirrel that spends considerable time on the ground and can gnaw through the hardest of nut shells.  By contrast the giant squirrel (Prototoxerus strangeri) is the most arboreal species.  The slender-tailed squirrel (Allosciurius aubinni)prefers swamp forests where it avoids  2 species of crocodiles by staying in the tree tops.  The red-legged squirrel (Heliosciurus rufobrachim) is completely arboreal and evolved in tropical forests, while the Gambian sun squirrel (H. gambianus) evolved on savannahs and still occurs there but has adapted to forests as well.  Pel’s flying squirrel (Anomalurus peli) glides between the trees.

Gambian Sun Squirrel

The Gambian sun squirrel lives within the Guinea/Ivory Coast forests.  It also occurs on savannah habitat and is a relic from when savannah was more prevalent here.

 Pel’s flying squirrel.

Zebra Duiker, Cephalophus zebra

Zebra duiker.

Giant Forest Hog - Kenya

Giant forest hogs are aggressive and dangerous and will attack people.

Male and female Western Red Colobus Monkey Piliocolobus badius together in a tree Stock Photo - 26138556

Western red colobus monkeys are endemic to this region.

Rufous Fishing Owl

 

 

 

 

 

 

 

 

 

 

 

 

 

The rufous fishing owl (Scotopelia ussheri) is another unique species endemic to the region.

All this spectacular wildlife can be found in Tai National Park, but unfortunately this is where the Ebola virus originated.  Chimpanzees contracted Ebola from hunting colobus monkeys.  People eating bush meat then became exposed to the deadly disease.  Though I’d enjoy seeing this diverse fauna, I think I’ll skip the chance that I might catch Ebola.

Reference:

Kingdon, Jonathan

Island Africa: The Evolution of Africa’s Rare Animals and Plants

Princeton University Press 1989

 

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