Conservation Status

We have already learned that Gorillas typically reside in tropical forests (with the exception of the Mountain Gorillas, which live in the mountains).  We also know that in recent years, humans have slowly been destroying forests throughout the world, due to our increasing populations and need for more residential and industrial space.  For this reason, all subspecies of gorillas are considered "endangered" because the largest threat to the gorilla population is habitat loss, which can be due to deforestation, wood extraction, infrastructure development, and human settlement.  Other threats to gorillas include direct killing for bushmeat trade, hunting for live animal trade, and diseases transmitted by humans, war, and political unrest.  Since gorillas share about 98% of the same genes as humans, they are very susceptible to catching human diseases, and vise versa.

On the plus side, many programs in Africa, as well as other parts of the world, have been established to protect gorillas.  For instance, there are laws in eight different African countries that govern gorilla hunting and capturing.  In addition, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is an international trade treaty that was developed in 1973 to regulate trade in certain endangered species, which includes gorillas.  Also, in 2000, the United States congress passed the Great Ape Conservation Act, which provides financial support for conservation projects that protect great apes in the wild.  

You can help too! The next time you buy wood or furniture, be sure to ask if it has been certified.  This means that the wood was taken in a way that has been approved by forestry experts.  Buying certified wood will encourage logging companies in Africa to follow wildlife laws that will help protect gorillas and other African animals.  Also, be sure to check out the gorilla exhibit at the San Diego Zoo!

Sources:

http://www.seaworld.org/animal-info/info-books/gorilla/conservation.htm 

http://www.naturalsciences.be/science/projects/gorilla/aboutgorilla 

http://www.pandrillus.org/projects/limbe-wildlife-center/ 

http://www.actnow.com.au/Issues/Deforestation.aspx 

http://www.sandiegozoo.org/animalbytes/t-gorilla.html 

Reproductive Behavior of Gorillas

Reproductive Behavior of Gorillas

Mountain Gorillas are polygynous, which means that the dominant males have access, and permission, to reproduce with all of the females in the group. However, the females are only able to birth an infant approximately every 4 to 5 years because she ceases to ovulate for a few years after birth. Therefore, the average number of offspring usually tends to be only one. Reproductive rates are also fairly slow, and if a female chooses to birth more than one offspring (anywhere from 2 to 6), it can be over the span of 40 years. This is why the males attempt to reproduce with more than one female, so they can increase the amount of offspring from their lineage. A male gorilla may father anywhere from 10 to 20 offspring over the course of 50 years.

         Mating behavior does not begin until the gorillas are sexually mature, which is about 10 years old for females, and 15 years old for males. Gorillas usually are nursed and cared for by their mother for the first three to four years of life, and then the toddlers stay with their group until they are sexually mature to leave. Females will go out and wander by themselves in search of a new group, and males venture off when they are about 12-13, recruiting new members and bachelors for their own new troop. (This prevents inbreeding). Unlike many animals, the female is the one to initiate mating behavior by slowly approaching the male, as well as giving off a specific odor that the males will pick up on when she is ready to mate. Gorillas are also “one of the only known animals to engage in different sexual positions other than humans,” (gorillas-world.com)

         Because of the time and maturity devoted to having one offspring, gorillas are said to be one of the best caregivers in the animal world. They provide the basic needs as wells as giving their children lots of affection. The mothers hold their babies similarly to human mothers and take their job of protecting their young very seriously.

Sources:

http://animaldiversity.ummz.umich.edu/site/accounts/information/Gorilla_beringei.html

http://www.gorillas-world.com/gorilla-reproduction.html

http://www.seaworld.org/animal-info/info-books/gorilla/reproduction.htm

(pictures)

http://i.dailymail.co.uk/i/pix/2010/06/02/article-0-098F92D8000005DC-380_634x941.jpg

http://5601-newswatch.voxcdn.com/files/2009/03/gorilla-and-baby-picture.jpg

Territorial Behavior

Gorillas are highly social, relatively non-territorial and live in groups (called troops) that usually consist of 1-4 adult males, some juvenile males, and several young and adult females.  The oldest and strongest adult male (called the silverback) is usually the dominant one of the troop and has exclusive breeding rights with the females.  Adolescent females transfer to a different troop once they reach about eight years of age. Generally, the first troop in which the female produces offspring becomes her permanent troop.  A female's status is usually determined by the earliness of her entry into the troop.  For instance, latecomers do not get as many benefits, which include protection of offspring by the dominant silverback.  For this reason, females do not have strong relationships with each other because they are constantly fighting to be closest to the silverback in order to receive the most attention and protection.

Adolescent males, on the other hand, usually remain in the troop until they can leave and establish a new troop on their own as the silverback.  Troop populations range from 2- 12 individuals, with 9 being the average size.  The silverback is typically the most aggressive member of the troop because he is the one who must provide protection and security.  He also makes all of the group decisions, settles disputes between members, and gets the majority of the group's food.

Although gorillas typically aren't aggressive, they do exhibit territorial behavior by standing upright on their bottom two legs and pounding their chests in order to intimidate whatever threat they have been given.  These gestures, however, are more for show and aren't usually violent.  These instances can come about when two silverbacks of different troops meet, when two males are fighting over a female that they want to mate with, or when a younger male is challenging the silverback for dominance of the troop.  However, in stable troops these acts of violence and aggression are very rare.

At dusk, gorillas settle down for the night in nests made of vegetation that is shoved around them.  These nests are initially made by bending soft trees, breaking bamboo sticks, and taking large leaves from other types of trees to be used as a blanket to shield from the cold.  Mothers like to find a comfortable spot in the nest where their backs can be supported so that they can breast feed and cuddle their babies throughout the night. 

Sources:

http://www.seaworld.org/animal-info/info-books/gorilla/behavior.htm

http://www.travelhemispheres.com/uganda-safaris/gorilla-safaris/gorilla5.html

http://www.google.com/imgres?um=1&hl=en&rlz=1C1SKPL_enUS425US425&authuser=0&biw=1333&bih=629&tbm=isch&tbnid=hJjxXhqXVIA60M:&imgrefurl=http://forums.sgclub.com/singapore/awesome_animal_dads_111073.html&docid=3jpGLiMepUIfSM&imgurl=http://i133.photobucket.com/albums/q61/Jdesign1/Awesome8.png&w=298&h=381&ei=1SVLT8ymF8fciQKv5MXbDQ&zoom=1&iact=rc&dur=432&sig=104890781443561885250&page=1&tbnh=140&tbnw=104&start=0&ndsp=19&ved=1t:429,r:5,s:0&tx=67&ty=68

http://www.google.com/imgres?um=1&hl=en&rlz=1C1SKPL_enUS425US425&authuser=0&biw=1333&bih=629&tbm=isch&tbnid=MKkLqjJ5ibyBxM:&imgrefurl=http://greatapediaries.wordpress.com/tag/bwinidi-impenetrable-forest/&docid=SI07oU0ZB_04yM&imgurl=http://greatapediaries.files.wordpress.com/2011/10/205178-2.jpg&w=500&h=331&ei=sCtLT927M-mSiQK_nIDaDQ&zoom=1&iact=rc&dur=395&sig=104890781443561885250&page=4&tbnh=105&tbnw=159&start=67&ndsp=24&ved=1t:429,r:2,s:67&tx=89&ty=25

http://www.google.com/imgres?um=1&hl=en&sa=N&rlz=1C1SKPL_enUS425US425&biw=1333&bih=629&authuser=0&tbm=isch&tbnid=c_0P8E8b7TrfLM:&imgrefurl=http://www.moneyandshit.com/male-gorillas-fighting/&docid=HOifB-kiufrSNM&imgurl=http://www.moneyandshit.com/wp-content/uploads/2010/10/male_gorillas_fighting.jpg&w=578&h=500&ei=nyxLT_SNGrPSiAL_-rTbDQ&zoom=1&iact=rc&dur=311&sig=104890781443561885250&page=1&tbnh=118&tbnw=143&start=0&ndsp=22&ved=1t:429,r:0,s:0&tx=112&ty=37

http://www.google.com/imgres?imgurl=http://www.debsimonphotography.com/images/western_lowland_gorilla_and_baby.jpg&imgrefurl=http://www.debsimonphotography.com/wildlife_photos.html&h=720&w=576&sz=114&tbnid=0WGbX5jEsxxg5M:&tbnh=90&tbnw=72&zoom=1&docid=QgH2BGjlqg137M&hl=en&sa=X&ei=xCxLT-OdEozYiAKf893bDQ&ved=0CDgQ9QEwAw&dur=305

Eating and Foraging Behavior

Gorillas’ eating behavior varies a bit depending on the subspecies, although all of them are predominantly herbivores. While the Eastern lowland gorilla eats predominantly plants (104 species), the Western lowland gorilla’s diet is composed of fruit, leaves, seeds, termites and caterpillars. The Mountain gorilla also eats a large variety of plants (142 different types) along with fruit, ants, and snails. All of the vegetation that gorillas eat has relatively low nutritional quality, which means that they must eat large quantities of everything. An adult male can consume approximately 40 to 50 pounds of foliage per day. They also rarely drink water because of the natural morning dew on the vegetation. Sometimes they also use the hair on the backs of their hands to “absorb moisture and then suck it,” (seaworld.org)

            Gorillas are also very selective when choosing what to eat. They never consume a whole plant, but instead will only forage for the leaves, pith, stalk, or roots. They also have extremely supple lips and hand agility, which assists them in only consuming the specific parts of they plant that they want. Gorillas’ incredible strength also allows them to be picky with what they eat, because they could break apart a whole tree just to get to the interior pith.

           

Uganda Mountain Gorillas specifically spend most of 60% of their time either eating or foraging, and the remaining 40% relaxing. They may feed as their moving, but will usually pick a quiet open area to spread out and eat until they are full. Most gorillas do this as well in the wild.

Sources: 

http://www.seaworld.org/animal-info/info-books/gorilla/diet.htm

http://www.ugandatourismguide.com/uganda-travel-news/daily-habits-of-mountain-gorillas/

http://animals.nationalgeographic.com/animals/photos/gorillas/#/western-lowland-gorilla-nibbling_5876_600x450.jpg

Introducing, Gorillas!

Evolutionary Background, Close Relatives, and Taxonomy

Gorillas are fascinating creatures because they are so like humans, yet still obviously have many very different qualities.  Both humans and gorillas share a common ancestor which was some sort of primate millions of years ago, however somewhere down the line the species diverged into two separate lineages.  One of these ultimately evolved into gorillas and chimpanzees, while the other evolved into humans.  Researchers believe that Gorillas began to differentiate from other apes and monkeys because they began to evolve into a larger and stronger species, which in turn caused a loss of agility and the gradual loss of a tail because their bodies eventually became too heavy to swing from trees. Instead, they began to swing with their powerful arms, which is why their arms are longer and stronger than their legs.  These strong arms also help for balance, and although they are able to stand and walk in an upright position, they are more comfortable on all fours with their knuckles being the point of balance.

The taxonomy of the Gorilla is as follows:
Kingdom: Anamalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Gorilla
Species: Gorilla and Beringei

Gorilla scientific classification has been divided into three subspecies based on where each is geographically located in Africa. The Western Lowland Gorilla (Gorilla gorilla gorilla) is the smallest of all three subspecies.  These gorillas typically live in the tropical forests of West Africa, and are the most common in zoos.  The Eastern Lowland Gorilla (Gorilla gorilla graueri) is slightly larger in size and typically resides in the rain forests of central Africa.  Finally, the Mountain Gorilla (Gorilla gorilla beringei) is the largest and rarest of all the subspecies.  These are naturally found in the Virunga Volcano range of Africa, and have darker coloring than the other subspecies because of the high altitudes in which they live.

It is very common to confuse apes with monkeys because the two words are often (wrongly) used interchangeably.  However, I would like to try and clarify a distinction between the two.  Gorillas are classified as apes, while others, like baboons for example, are classified as monkeys.  The main detail that differentiates apes from monkeys is that apes do not have tails while monkeys do.  Also, apes typically having larger body sizes and weights, as well as more of an upright body position.  Great apes also tend to be more ground-dwelling than monkeys who are typically more tree-dwelling.  This distinction has led to many evolutionary changes in the muscle and skeletal structure of the arms of apes because they are not as adapted to things like swinging from trees as monkeys are.  So, while gorillas indeed appear to be very similar to their other primate relatives, it is important to keep in mind the details and characteristics that separate them as apes from monkeys.

Fun Fact: Humans are more closely related to chimpanzees and gorillas than either of them are to orangutans!

Sources:

http://www.gorillas-world.com/gorilla-evolution.html

http://www.seaworld.org/animal-info/info-books/gorilla/scientific-classification.htm

http://www.pbs.org/wgbh/evolution/library/faq/cat02.html

http://www.google.com/imgres?um=1&hl=en&sa=N&rlz=1C1SKPL_enUS425US425&authuser=0&biw=1333&bih=629&tbm=isch&tbnid=bOnirA3yjkYM8M:&imgrefurl=http://true-wildlife.blogspot.com/2011/04/western-gorilla.html&docid=jB3VRUblkU6P8M&imgurl=https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguihAhM3etFynYpbDyjp0Jw4oi1mePgjrz17Tp7Ou4zYM74JYUzivh9gBr_TMqGmjPFb6OUb2xlspHu05VWIMtVz0MTIG8KQjznmOZikH5CyJd-kb-mDMOInbiBFhDNzAo0PNcwziCXoI/s1600/Candid%252BWestern%252BLowland%252BGorilla.jpg&w=1600&h=1200&ei=Hz84T6qzFIeciAKyq6GfCg&zoom=1&iact=rc&dur=307&sig=104890781443561885250&page=1&tbnh=131&tbnw=176&start=0&ndsp=23&ved=1t:429,r:20,s:0&tx=137&ty=59