topics: |  gorilla |

this book from the early 90's gives the essential facts about this much-misunderstood species. the sparse text and vivid images describe the lifestyle of the gorilla in a child-friendy manner.

It deserves a new edition with updated facts.

Excerpts

Unfortunately, it is we humans who can be the ferocious, destructive primates, not gorillas. - from preface by jane goodall

gorillas: three (or two?) subspecies

mountain gorilla (western):

found chiefly on the slopes of the Virunga Volcanoes, a mountain range across Rwanda, Uganda, and Zaire. There, gorillas are found in the dense, misty forests, at altitudes of up to 12,000 feet.

lowland gorilla (eastern):

lives in the damp, hot rain forests of Cameroon, Gabon, Congo Brazzaville, the Central African Republic, and Zaire. They avoid clearings and stay in densely wooded areas.

There is only one species of gorilla. Within this species there are three subspecies—the mountain gorilla (Gorilla gorilla beringei), the eastern lowland gorilla (Gorilla gorilla graueri), and the western lowland gorilla (Gorilla gorilla gorilla).

These subspecies differ only slightly in their skull and body structure. The mountain gorilla, because it lives in a colder mountain environment, has longer, thicker hair than the lowland gorilla. It is also a deeper black. The eastern lowland gorilla is the largest. p.7

mountain gorilla species debate

alternate species classification from WWF: 

Two species: Western and Eastern Gorillas

Western gorilla: 
  - Western lowland gorilla (G. g. gorilla), 
  - Cross River gorilla (G. g. diehli) 

Eastern gorilla: 
  - Mountain gorilla (G. b. beringei) 
  - Eastern lowland or Grauer’s gorilla (G. b. graueri)

The two gorilla species live in equatorial Africa, separated by about 900km
of Congo Basin forest. Each has a lowland and upland subspecies.

from http://worldwildlife.org/species/mountain-gorilla: 

The world’s small population of mountain gorillas—a subspecies of the
eastern lowland gorilla — is split in two and scientists have debated
whether they may be two separate subspecies.

A bit more than half live in the Virunga Mountains, a range of extinct
volcanoes that border the Democratic Republic of Congo, Rwanda and
Uganda. The remainder can be found in the Bwindi Impenetrable National Park
in Uganda. 

Since the discovery of the mountain gorilla subspecies in 1902, its
population has endured years of war, hunting, habitat destruction and
disease—threats so severe that it was once thought the species might be
extinct by the end of the twentieth century.

gorilla population and distribution

 
distribution of the gorilla.  population numbers are from 2013 data; the
figures given in the book are ~45K for the Western and 450 for the Eastern
(or mountain) gorilla.  (population labels added)

alternate interactive (google) maps: 





Also: click for a more detailed map 

both above maps from http://wwf.panda.org/what_we_do/endangered_species/great_apes/gorillas/

gorilla lifestyle

The only natural predator of the gorilla is the leopard, which may prey on
young or weak gorillas.

It rains a great deal in gorilla territory. Gorillas sometimes
take shelter under a tree or sit motionless with arms crossed
and head down. When the sun comes out, they seem to enjoy
it, and sprawl out to take sunbaths. p.4

Like other animals, the gorilla lives in a steadily shrinking habitat. Where
there were once thick rain forests, there are now farms, grazing lands, and
villages. As man’s land use expands, the gorillas are forced into smaller and
smaller areas.  Between 40,000 and 55,000 lowland gorillas survive in the
wild. But the mountain gorilla population is down to about 450.  p.21

gorilla population update 2013

Thanks to intense conservation efforts, wild gorilla populations have been
rising slowly since the 1990s, when this book was written.

from WWF: 

The lowland subspecies are more numerous and widespread than the upland and
mountain subspecies. Mountain gorillas are the only gorillas to show an
increase in numbers, but the overall population size is still very low.

The western lowland gorilla is the most widespread, possibly numbering
100,000.
 
The Cross River gorilla is currently the world’s rarest great ape, with a
population of only around 250-300 restricted to a small area of highland
forest on the border of Cameroon and Nigeria.
 
There is no reliable estimate of the eastern lowland gorilla population;
however at one time it could have reached 17,000 individuals.
 
The total population of mountain gorillas is around 786 individuals, split
into two separate groups.

gorilla social groups

about 12 (can range from 5 to 40). 

The group led by a mature male gorilla called a silverback. He gets his name
from the silvery-gray hair that first appears on his back when he is eleven
or twelve years old.  The color sets him apart from the other gorillas, who
are totally black.

The silverback decides where the group should wander for food, and when and
where it should stop to rest.  At the end of rest-time the leader gets up and
faces in a certain direction. The group knows that this is the way they will
be going.

The leader protects the group as well. He does this by means of threats,
not violence. He will approach an intruder (either gorilla or human) and
just stare. He may stand up, beat his chest, and toss some twigs in the
air. If the stranger still doesn’t go away, he might rush at him. Still,
unless the group is really in danger, the silverback usually doesn’t
fight. He will either stop short or run right past the intruder.

 
silverback gorilla drawing by sophie and daniel, c. 2010

Until recently, we thought that the gorilla was a fierce, aggressive
animal. But in recent years, gorillas have been observed at close range for
long periods of time by ethologists, who have discovered that despite the
gorilla’s great strength and fierce appearance, it is one of the shyest and
gentlest of animals. Only in areas where gorillas have been hunted frequently
by humans are male gorillas likely to attack on sight.

Gorillas will not abandon their wounded unless they are forced to. They will
defend their young to the death. p.8


Gorillas have broad chests and very long arms. Their outstretched arms can
span eight and a half feet — more than their height. 

The average weight of male gorillas is about 400 pounds. Females weigh about
200 pounds. p.9

Gorillas, like chimpanzees, don’t seem to be able to swim.
Several times, when zoo gorillas fell into moats surrounding
their space, they made no effort to swim, and they drowned. 10

Scientists think gorillas’ eyesight, hearing, and
sense of smell are about the same as those of humans. 12

 
gorillas and humans had a common ancestor about 8 mn years ago. 

gorilla communication

Like most animals, including humans, gorillas often communicate through
body language. 

To a gorilla, staring acts as a threat.  A silverback will stare and beat his
chest if intruders come too close. Then he may rush toward the intruders,
stopping only at the last instant. He may also stand erect and toss twigs and
grass up in the air. These are all ways of sending out the message: “Go
away.”

If a fight is about to erupt between two gorillas, one may crouch on the
ground and look down, away from the other.  This is the way he says, “I give
up.”

Gorillas also communicate vocally. They make at least twenty-five different
sounds, all meaning different things.  They grunt and roar when they are
threatened, and hoot when they are alarmed. They bark when they are
curious. A belchlike sound means they are feeling good. A mother trying to
discipline her young makes piglike grunts. And there is a special kind of
humming sound gorillas make that is connected with food.

Dian Fossey, a scientist who spent many years observing mountain gorillas,
decided to make some of these sounds while she was watching them. First,
though, she made sure she knew what the sounds meant to the gorillas. (She
did not want to make hostile sounds.) When she hummed, two of the young ones
came close to her. Maybe they thought she had some food for them.

Because of the way their vocal cords are formed, gorillas are not able to
talk as we do. But Koko, a captive gorilla in San Francisco, has learned to
communicate with people using American Sign Language, the system of “signing”
used by people who cannot speak or hear. Koko has learned more than 600
signs. She also made up some new signs of her own. When

referring to a nut, she called it a “rock fruit.” She can say, “Come tickle
me.” She can also communicate by using a computer. When she presses certain
keys, different words are made. p.13

gorilla babies

Gorilla young are born weak and helpless, but they develop faster than
humans. At six weeks of age, the infant gets its first teeth. At about two
and a half months it begins to eat plant food—leaves, shoots, and fruit,
though it still continues to nurse from its mother.

At birth, the infant weighs about four and a half pounds. Its skin is
chocolate-brown; its fur is shiny black. At first the mother has to hold it
to her chest, because it is not strong enough to cling to her. Soon it can
cling to its mother’s back and travels “piggyback.” When the mother sits,
she holds the infant in her arms, so it can nurse. When it rains, she
hunches over it to keep it dry, even though she herself is getting soaked.

At three months, the infant gorilla begins to crawl. At four and a half
months, it begins walking on all fours. At five or six months, the young
gorilla can climb trees. By now it weighs about fifteen pounds.

A gorilla in the wild may live fifty years.

One of the most unusual gorillas is Snowflake, who lives at the Barcelona
Zoo, in Spain. Snowflake is an albino gorilla.  This means its skin and hair
lack normal color. Pink-skinned and blue-eyed, this white gorilla was found
in western Africa.  It was clinging to a black gorilla who had been shot and
killed.

Gorillas, along with chimpanzees, are more like humans than any other
animal. They share our emotions. They can laugh and be happy. They can also
be sad. They will give up their lives to protect their young. Can we humans
be so uncaring as to let them become extinct? 21

links

* kids' reviews with drawings on gorilla behaviour: 
	http://sfsanimalresearch.pbworks.com/w/page/32958540/Gorilla%20Communication%20and%20Behavior

* http://wwf.panda.org/?206716/Mountain-gorilla-population-grows

	13 November 2012: 

	The total world population of mountain gorillas has risen to 880,
	according to census data released today by the Uganda Wildlife
	Authority. The number of mountain gorillas has increased from the
	2010 estimate of 786 after a count in Uganda’s Bwindi Impenetrable
	National Park. 

	A total of 400 mountain gorillas have been confirmed to be living in
	Bwindi and 480 were counted in the Virunga Massif in 2010. Both
	populations have had positive trends in population growth over the
	last decade.

* http://worldwildlife.org/species/mountain-gorilla

* Angelique Todd's work talking to gorillas: the Telegraph

	Angelique Todd, a 43-year-old mother from Tunbridge Wells, has been
	called the 'gorilla whisperer' for the effect she has on
	Makumba. This is misleading because when she sees Makumba she doesn't
	actually whisper, she makes a soothing sighing noise, accompanied by
	clucking. It's like an invisible barrier between her and the
	gorilla. He may come close – really close – but Todd stays calm, no
	matter what. And Makumba, 400lb of alpha male, turns away.

	The thing about being so close to wild gorillas is that you must not
	run if they come at you. You are supposed to stand still and look at
	the sky. I ask Todd if Makumba has ever charged her. 'Oh yes, many
	times,' she replies. 'All silverbacks have different ways of being
	scary. Makumba charges really close to you, and then he jumps even
	closer. It's rather shocking.' [...]

	This is a woman who, aged 25, had her thumb, a finger and a large
	part of her right forearm bitten off by a chimpanzee when she was
	working as a keeper in Port Lympne Wild Animal Park, Kent. She was
	standing outside the chimp's cage when it grabbed her arm, pulling it
	through the bars. Now the arm is fully functioning but badly
	scarred. 


also see http://www.thesun.co.uk/sol/homepage/features/3631701/From-Croydon-to-the-rainforest.html