Western Lowland Gorilla
This population occurs within the countries of Cameroon, Central African Republic, Gabon, Republic of Congo, and Equatorial Guinea. The largest of the gorilla populations, with approximately 150,000 individuals across Central Africa, gained a large boost in known numbers when researchers from the Wildlife Conservation Society discovered an unknown (to researchers) population in 2006/2007 in the Republic of Congo which in effect doubled their numbers in the wild from previous estimates. For more information you can link to: http://www.cnn.com/2008/WORLD/africa/08/05/congo.gorillas/index.html
The Western Lowland Gorilla is listed as Critically Endangered even though they occur over a wide area with relatively low human population densities. The fragmented subpopulations generally occur at low numbers and their distribution is patchy with an estimated 80% of the population live outside protected area.
Western Lowland Gorilla photo courtesy Thomas Breuer
Currently the major threats to this population are poaching and disease epidemics such as the Ebola Virus followed by future habitat loss. Outbreaks of the Ebola virus alone since 2000 has claimed thousands of great apes in Africa.
Because gorillas have a low reproductive rate, they are very susceptible to even low level of hunting which can easily fragment a family unit’s social structure. Reproductive groups of Western Gorillas almost always contain only one dominant silverback male plus three or four females and four or five offspring (Fay, 1989). Adult females in any group are mostly unrelated, and the social ties that exist between them are weak. In contrast to many other primates, it is the bond between each individual female and the silverback, rather than bonds between the females, that hold the group together. Upon reaching maturity, both males and females leave the natal group. The females usually join another group or a lone young adult male, whereas the males remain solitary until they can attract females and establish their own groups (www.YOG2009.org).
We have mentioned Eastern Lowland Gorillas and Western Lowland Gorillas and the two populations are separated geographically by over 600 miles and have a few distinguishable physical differences.
The Houston Zoo is proud to support the Mbeli Bai Gorilla Study in Nouabalé-Ndoki National Park, Republic of Congo. More on this in a later blog but for now you may go to http://www.houstonzoo.org/gorilla-study/ for more information and to watch a short video from the site.
The Houston Zoo is hosting Dr. Michael Cranfield, Executive Director of the Mountain Gorilla Veterinary Project as part of our Call of the Wild Lecture Series September 10th, 20009. Please go to http://www.houstonzoo.org/lectureseries/ for ticket information.
Tomorrow’s Blog: Cross River Gorilla – the world’s most endangered great ape.
For more on Year of the Gorilla, go to http://www.yog2009.org/
*This is part 2 of 10 in our Mountain Gorilla Membership Madness giveaway. Post a comment on 3 mountain gorilla blogs before August 14 and enter to win a free Houston Zoo membership!
Didn’t know lowland gorillas moved is such small reproductive groups. Always thought they migrated in groups of 15-20. Thanks for the info.
There is a big difference between eastern and western lowland gorillas. Other than human interaction, why is this population thriving?
The difference in the size of the populations at this point is closely related to the effect of human activity, civil conflicts and pressures with a large number of Western gorillas living in remote swamp forest in the Rep. of Congo. The fact that the Eastern species only lives in the Democratic Rep. of Congo (DRC) has had a large impact on this population. This statistic really points to the issue at hand with the DRC gorillas: “91% of the human population in the region practice subsistence farming, which requires them to convert the forest into agricultural land. Over 96% of these people rely on firewood, often harvested unsustainably, as their main energy supply for warmth and cooking. Forested parks are for many of them the last remaining source of fuel.”
I read the info on the study and it’s exactly what I had mentioned in a previous blog, about education. Club Ebobo is an excellent way to show public awareness because they start with educating our future generations. I would love to see this study 15 years into the future to see the impact it made on these children, now adults.
Western lowland gorillas way of life is very interesting. Even in their population females seem to be over populated than the male counterpart.
When thinking of gorilllas you typically don’t think of them living in a swamp area. It’s interesting to see that the largest population of Western Lowland Gorillas were found in one.
I’m really looking forward to the speaker in September. I saw the one last fall about the lemurs. You guys offer the best lectures!!
How long do young gorillas stay with their group? Is this part of their slow reproductive rate? Or are there only a limited number of females that tend to be pregnant at the same time?
Young normally wean at around 3 years of age and females will stay in their group until about 6-8 years of age at which point thye may disperse out to another group, join a male or othre females. Males may stay in heir group up to 10 years or more. Given that it takes 3-4 years for young to start becoming self-sufficient, there is a slow reproductive rate among gorillas.
Gorillas really are very interesting animals… its good to hear all about them
It is very interesting to learn how gorillas live and how the females are usually unrelated and how the group is held together by the bond to the male and not to the other females; also how males when they leave the group are on their own until they attract females, and the females join another group. I learn something new everyday about gorillas. Thanks so much for the blog and I look forward to tomorrow’s.
Thank you for providing such great information. I assume the Zoo provides education to school aged kids too. We don’t care about things we don’t know abour.
wow I didnt know that… they should stop poaching them there beautiful animals that deserve to live.
I had no idea they were susceptible to Ebola. Can they catch all human diseases? How do we protect both the human and gorilla population from mass epidemics?
are more types of gorillas coming to the zoo? when and what kind?
Is there any kind of vaccine for the Ebola Virus? Perhaps there could be a way to set up some sort of food intake of a vaccine for the gorillas…if there was anything possible for the gorillas.
I do hope the efforts being made to educate people of this current situation and the plans to save these gorillas is successful. I remember fondly of going to the zoo as a child and the gorillas were always my favorite. I want my children to have the same opportunity. Thank you for making us aware and continue to educate us and our children, so we can do our part.
Do the females “babysit” for each other as do animals in other groups?
Did you know? Western lowland gorillas live in the smallest family groups of all gorillas, with an average of four to eight members in each. Maybe this is why they have such a low reproductive rate.