Grauer's Gorilla

Gorilla beringei graueriBy Jaclyn Janero

Gorilladoctorsblog.com

{Introduction}

Taxonomic Classification

Grauer’s gorilla’s classification down to the

subspecies level.

Grauer’s gorilla classification down to the

genus level.

Jaclyn Janero

Geographic Distribution

Range of Eastern gorillas, with Grauer’s gorilla marked in green.

wikipedia.org

Grauer’s gorilla has three prominent populations: - Maiko National Park, - Kahuzi-Biega National Park, - Itombwe Natural Reserve All three are in the Eastern Democratic Republic of Congo in Africa (Mittermeier, 2012).

Habitat

Grauer’s gorillas occupy habitats from lowland tropical forests to

higher montane forests (Yamagiwa, 2005).

Baraza.wildlifedirect.org

Map of gorilla distribution with terrain.

Activity Patterns

Grauer’s gorillas are diurnal, with intense morning feeding and an additional eating

phase in the late afternoon.

This second eating phase is followed by

a dusk-time nest building session (Remis, 1997).

www.wcs.org

Gorilla beringei graueri during nest building.

Locomotion

A Western Lowland Gorilla exhibiting knuckle-walking.

Wikipedia.org

Gorilla beringei graueri travel on the ground by knuckle-

walking but use forelimb suspensory adaptations in trees. Males are cautious in trees and tend to stay closer to tree trunks; youngsters

and females can move further from

the trunk since they have lower body mass (Doran &

McNeilage, 1998).

DietG. b. graueri is omnivorous. Fruit consumption

increases when fruit abundance is high. They also eat copious amounts of bark. Grauer’s gorillas have a preference for figs, as do sympatric chimpanzees,

making competition for this fruit high. The two species often encounter one another around fruiting

trees; neither will approach the other, leaving the population who finds it first free to forage.

Grauer’s gorillas have been observed eating insignificant amounts of animal proteins. In times of food shortage, Grauer’s gorillas engage in geophagy and rotten wood consumption. Their total body mass

also allows them to fall back on leaves.Consumption of whole Commelina cecilae leaves,

without chewing, may trap and expel parasites, such as nematodes, making this a medical endeavor

(Yamagiwa, 2005).

Social StructureGrauer’s gorillas have multimale-

multifemale social structures.

Males and females tend to leave their natal groups around

maturity. Females

immigrate into other groups or

join solitary males to form new groups.

The range of Gorilla beringei graueri group size is from 2 to

20 individuals (Yamagiwa, 2003).

ReproductionMungaiaandthegoaconstrictor.wordpress.com Females have a 25 year

reproductive life with a 4.6 year interbirth interval.

Females become reproductive around age 6 (Czekala & Robbins, 2001)

and each successfully produces an average of 3 to 5 offspring before her death.

There is a 26% infant mortality rate

(Yamagiwa, 2003). Though groups have a dominant male, the silverback, it is

the female who chooses her mate. Females may copulate

with both silverback and blackback males (Bradley,

2005).

Mother Grauer’s Gorilla with Infants

Usually there is only one silverback in a social group. However, silverbacks do not

monopolize reproduction in groups with multiple males. Females prefer the silverback, but avoid

breeding with relatives. Hence, blackback males are sometimes chosen (Bradley, 2005).

A Male Eastern Lowlands Gorilla in Threat Posture

{Conservation}

According to the IUCN Red List, Gorilla beringei graueri is endangered with

expectations of population decline in the future of nearly 50%.

This aligns with additional conservation data I have obtained from other sources. However, population numbers and range tend to fluctuate (Mittermeier,

2012). One researcher pinpoints smaller populations and their locales as being just as important to

preserve as the top 3 endangered primates designated in the IUCN Red List (Nixon, 2006).

The IUCN reports 2,000 to 10,000 individuals across all populations of Grauer’s

gorillas. The reason for disparity in

reports is that the Democratic Republic of

Congo is a war zone, making accurate data

difficult and dangerous to obtain.

Remote sensing techniques have been

utilized, but not effectively (Nixon, 2006).

A very basic diagram of remote sensing.

Coolclassroom.org

Poaching, as well as hunting for bushmeat, is a major cause of population

decline. Silverbacks are killed for the sale of their pelts. In

2005, five silverbacks were killed around the same time, resulting in havoc for the affected gorilla communities, which took months to

recover. A silverback can also be

killed by refugees in order to honor

transactions with local businessmen (Kasereka,

2006).

Poachers Showing the Backpack They Smuggle Gorilla Infants In

Virunga.org

In 1996, park rangers in the Democratic Republic of Congo were disarmed, allowing poachers

to run rampant. Gorillas were massacred until the rangers were eventually

re-armed in May of 2000 (Kasereka, 2006).

Gorillas.org

Habituated gorillas and those that are settled into a social group are less aggressive. They generally don’t

defend themselves from poachers and are easy targets. Habituated gorillas are hunted mainly for their meat and to capture infants for illegal export

and resale (Kasereka, 2006).

Wexas.com

Other threats include deforestation and cattle encroachment. Many gorillas are wounded by

antelope snares as a side effect of human habitation (Yamagiwa, 1992).

A Ranger Stands With Two Months of Found Snares

Human population density

has recently increased due to

the influx of refugees from Rwanda. This

creates pressures on the

environment. In 1998, Gorilla beringei graueri had no contact

with populations that were further

apart geographically

(Saltonstall, 1998).

Rwandan Refugee Camp in Democratic Republic of Congo

Map of the UGADEC corridor (in orange)

in the DRC.

Charcoal production, mining, and slash-and-burn agriculture are also prevalent. In 2000 and 2001,

approximately 15,000 people migrated to the park to mine coltan when the price skyrocketed by more than 10 times. Coltan is refined into tantalum, a heat-resistance powder

that holds a high electrical charge. It is used in almost every electrical device that is currently produced, most

notably cell phones.

An Example of Slash-and-Burn Agriculture

Ecos.efpl.ch

These human activities caused permanent damage. This damage was greatest in the corridor that connects the main populations of Grauer’s

gorilla. By 2008, 60% of the corridor was degraded (Yamagiwa, 2012).

An Example of Slash-and-Burn Agriculture

Ecos.efpl.ch

Closure of public services, such as clinics & transportation, increased the need to use park plants

and vegetation for construction, food, fuel, and medicine. Starvation brought on by the economic and political crisis increased food needs, pushing people to

use more park resources (Yamagiwa, 2012).

Worldwildlife.org

Refugees Taking Park Resources for Fuel in Virungas Park, DRC

When the parks were created, many people were displaced from their homes and areas of cultural

significance. They were also prohibited from shooting elephants that frequently raided and

destroyed their crops. These individuals live on the outskirts of the park and frequent it for resources, further depreciating the park (Yamagiwa, 2012).

Coconut Trees Destroyed by Elephants

Seeingthewoods.org

To prevent further species loss, parks

should work on restoration and

preservation of the corridor that

connects the gorillas, to prevent genetic

isolation (Saltonstall, 1998).

A Map of the Democratic Republic of Congo, Showing the Corridor Between the Two Parks

(UGADEC)

Janegoodall.ca

Patrols of the parks by armed rangers need to be more frequent to watch for traps and poachers

(Yamagiwa, 1993). Surveillance of the entire park, instead of just the tourism area, needs to be

implemented (Kasereka, 2006).

Park Rangers in the Democratic Republic of Congo on Patrol

Boingboing.net

Cooperation with local populations and refugees may be the Grauer’s gorilla’s best chance, as well as the impacted human populations. Yamagiwa et al (2012)

provide five comprehensive alternative solution outlines for this, which I agree with:• Promote local animal breeding projects and fish farming to

increase the availability of off-park resources

• Plant trees in excess to supply communities with wood and other resources to be managed rationally

• Promote farming to increase food stability and security while educating the community on sustainable practices

• Promote projects that use sustainable techniques to meet fuel needs and implement management strategies for farming (IE: vegetable oil from locally grown peanuts or sunflowers)

• Promote income activities that also increase economy; can include development of a fair trade system alongside ecotourism

Why is Grauer’s Gorilla conservation an anthropological concern?

Grauer’s gorillas are closely related to humans, a relationship emphasized by both Darwin & Huxley; they connect us to our ancestral past (Scally, 2012). Sadly, they also provide evidence of “unnatural” extinction and population fragmentation and crises due to human actions. For these reasons, the conservation of Grauer’s Gorilla is of anthropological concern.Plus, they are adorable!

Mungaiandthegoaconstrictor.com

Vetstreet.com

Works Cited• Bradley, Brenda J., with Martha M. Robbins, Elizabeth A. Williamson, H. Dieter Steklis, Netzin Gerald

Steklis, Nadin Eckhardt, Cristophe Boesch, and Linda Vigilant. 2005. Mountain Gorilla Tug-of-War: Silverbacks Have Limited Control Over Reproduction in Multimale Groups. PNAS 102(26): 9418-9423.

• Czekala N, with Robbins MM. 2001. Assessment of reproduction and stress through hormone analysis in gorillas. In: Robbins MM, Sicotte P, Stewart KJ, editors. Mountain gorillas: three decades of research at Karisoke. Cambridge (England): Cambridge Univ Pr. p 317-39.

• Doran, Diane M., with Alastair McNeilage. 1998. Gorilla Ecology and Behavior. Evolutionary Anthropology 120-131.

• Kasereka, Bishikwabo, with Jean-Berckmans B. Muhigwa, Chantal Shalukoma, and John M. Kahekwa. 2006. Vulnerability of Habituated Grauer’s Gorilla to Poaching in the Kahuzi-Biega National Park, DRC. African Study Monographs, 27(1):15-26.

• Mittermeir, Russell A., with Christoph Schwitzer, Anthony B. Rylands, Lucy A. Taylor, Federica Chiozza, Elizabeth A. Williamson, and Janette Wallis. 2012. Primates in Peril: The World’s 25 Most Endangered Primates 2012-2014.

• Nixon, S.C., with K. Mufabule, D. Bolamba, B. Mulley, and P.T. Mehlman. 2006. Landscape-Wide Conservations Status and Distribution of Grauer’s Gorillas (Gorilla beringei graueri) In Eastern Democratic Republic of Congo (DRC). International Journal of Primatology 27:427.

• Remis, Melissa J. 1997. Ranging and Grouping Patterns of a Western Lowland Gorilla Group at Bai Hokou, Central African Republic. American Journal of Primatology 43:111-133.

• Saltonstall, K., with G. Amato and J. Powell. 1998. Mitochondrial DNA Variability in Grauer’s Gorillas of Kahuzi-Biega National Park. Journal of Heredity 89:129-135.

• Scally, Aylwyn, et al. 2012. Insights Into Hominid Evolution From The Gorilla Genome Sequence. Nature 483:169-175.

• Stanford, Craig B. 2001. The Subspecies Concept in Primatology: The Case of Mountain Gorillas. Primates 42(4):309-318.

• Yamagiwa, Juichi, with Ndunda Mwanza, Andrea Spangenberg, Tamaki Maruhashi, Takakazu Yumoto, Antja Fischer, and Bernd Steinhauer-Burkart. 1993. A Census of the Eastern Lowland Gorillas Gorilla gorilla graueri in Kahuzi-Biega National Park with Reference to Mountain Gorillas G. g. beringei in the Virunga Region, Zaire. Biological Conservation 64:83-89.

• Yamagiwa, Juichi, with John Kahekwa and Augustin Kanyunyi Basabose. 2003. Intra-specific Variation in Social Organization of Gorillas: Implications for Their Social Evolution. Primates 44:359-369.

• Yamagiwa, Juichi, with Augustin in the Montane Forest of Kahuzi, Kiswele Kaleme, and Takakazu Yumoto. 2005. Diet of Grauer’s Gorillas in the Montane Forest of Kahuzi, Democratic Republic of Congo. International Journal of Primatology 26(6):1345-1373.

• Yamagiwa, Juichi, with Augustin Kanyuyi Basabose, John Kahekwa, Dominique Bikaba, Chieko Ando, Miki Matsubara, Nobusuke Iwasaki, and David S. Sprague. 2012. Long-Term Research on Grauer’s Gorillas in Kahuzi-Biega National Park, DRC: Life History, Foraging Strategies, and Ecological Differentiation from Sympatric Chimpanzees. Long-Term Field Studies of Primates: 385-412.