World Gorilla Day 2020

World gorilla day is the day to celebrate Gorillas.  It is the same day that Dian Fossey established Karisoke Research Centre in 1967. 

A few gorilla facts

Gorillas are the largest living primates in the world. They are our closest living relative after chimpanzees and bonobos.  Humans share 95 – 98% of our DNA with gorillas.

They spend much of their life living on the ground. Gorillas are gentle giants and exhibit many human-like behaviours, such as sadness, happiness, and laughter.

They are social animals living in troops of up to 50 individuals led by one dominant male, called a ‘silverback’ due to the silvery fur on its back.  The dominant silverback will hold his position as leader for many years, until he is challenged by another dominant male, or he becomes too old and weak to continue lead. 

Mountain gorilla
Mountain gorilla silverback, Bwindi National Park, Uganda

Females will begin to reproduce around 8 – 10 years of age. Female gorillas will give birth to a single infant every 4-6 years and will only ever have 3 or 4 infants during their lifetime. Gestation is around 9 months.  Their low rate of reproduction significantly impacts the ability for them, to increase their population at a faster rate.

They are herbivores, eating fruits, leaves, berries, plants and insects and play a crucial role in seed dispersal.

  • Lifespan ~ in the wild, 35-40 years, in captivity 50 years.
  • They create nests both on the ground and in trees for sleeping
  • Gestation is 9 months
  • They are very shy and non-aggressive unless challenged
  • Gorillas walk using their back legs and knuckles of their hands
  • Gorillas have only 1 predator:  HUMANS
  • All species of gorillas are critically endangered according to IUCN Red List of Endangered Species. 
Mountain gorilla with her infant
Female mountain gorilla with infant, Bwindi National Park, Uganda
Silverback mountain gorilla, Bwindi National Park, Uganda
Silverback mountain gorilla, leader of his troop, Bwindi National Park, Uganda
there are two main Species of gorillas in the world

The eastern gorilla and the western gorilla. Each of which has two subspecies. Their habitat is the tropical and subtropical regions of the African Continent.  What they both have in common is that they are both endangered.

Eastern gorilla (Gorilla beringei)

These gorillas are the largest living primates. Their habitat is the sub-alpine and mountain rainforests of Uganda, Rwanda, and the Democratic Republic of Congo. They have large stocky bodies, big heads, broad chests, and long arms. The Eastern gorilla is covered in black fur, apart from their chests, face, feet, and hands which are bare. Fully grown males weigh 150 – 205kg and females around 90 – 100 kg.  These gorillas live in stable family groups with one dominant silverback male as their leader. These gorillas are critically endangered, their numbers are decreasing due to habitat loss, illegal hunting for body parts and bush meat, and human-wildlife conflict. And their population has declined more than 70% in the past 20 years (IUCN Red List of Endangered Species).

The two subspecies of the eastern gorilla are:
  • Mountain gorilla (Gorilla beringei beringei) 
  • Eastern Lowland gorilla or Grauer’s gorilla (Gorilla beringei graueri)

The Mountain gorilla is one of the world’s most endangered primates. They are found high up in the forests of the Virunga Volcanic Mountains at around 2500 – 4000 metres elevation. The Virunga Mountains border Uganda, Rwanda, and the Democratic Republic of Congo. Their current population of around 1000+ (2018 census). Mountain gorillas are about the same size as their cousins, the Cross River gorilla. These gorillas have thicker and more dense fur which is needed to keep them warm in their high elevation habitat. The gorillas are also at risk of extinction due to habitat loss needed by expanding the human population, land for agriculture, deforestation and poaching by humans.

Fig eating mountain gorilla, Bwindi National Park, Uganda
Mountain gorilla enjoying fresh figs, Bwindi National Park, Uganda

Eastern Lowland or Grauer’s gorilla are found in the tropical rainforests of the Democratic Republic of Congo. Over the past 50 years, their habitat has been significantly reduced and is now only 13% of their original habitat size. Their population has declined by more than 50% over the past 30 years. These gorillas have black hair which is shorter than the mountain gorilla. They are subject to the same threats as all other gorilla species. 

Western gorilla (Gorilla gorilla)

The largest population of gorillas. They differ from the Eastern gorilla by their fur. It is lighter and ranges from greyish, brownish and they can have a yellowish forehead. They also have an overhanging tip on their nose. Their height is approximately 135 – 155 cm when standing. They live in troops of 2 – 20, comprising of younger males, females, and infants. The troop is controlled and guarded by one dominant male. Diet consists of fruits, leaves, bark, stems, etc. Western gorillas are classified as critically endangered. Their biggest threat is Ebola, which has wiped out around 33% of their population in protected areas.  Due to the increasing human population, more land is required and much of the gorilla’s habitat has been lost for new homes, agriculture, grazing livestock, and timber.  Poaching is also occurring for body parts which are contributing to their declining numbers. WWF, Cameroon, and Nigerian governments, and other organisations are working to create protected areas for these gorillas.

THE TWO SUBSPECIES OF THE western gorilla are:
  • Cross River gorilla (Gorilla gorilla diehli)
  • Western Lowland gorilla (Gorilla gorilla gorilla)

Cross River gorilla‘s habitat is the forested hills and mountains at the border of Nigeria and Cameroon, near the Cross-River’s headwaters. Their population is around 250 individuals and is the world’s rarest of the great apes. These gorillas have a smaller palate and a noticeably smaller skull in relation to the size of their body. They are critically endangered, and the rarest of all apes (IUCN Red List of Endangered Species).

Western Lowland gorilla‘s habitat is the lowland swamps and montane forests of central Africa. They can be found in Angola, Cameroon, Democratic Republic of Congo, and the Central African Republic. These gorillas are the smallest of the western gorilla subspecies. Despite their smaller size, they are still as strong as their larger cousins. They have black skin and coarse hair covering their entire body. 

Western lowland gorilla, Taronga Zoo
Western lowland gorilla, Taronga Zoo, Sydney
Threats ~ humans

The following threats apply to all species of gorillas.

  • Low reproduction rates ~ make them vulnerable to population declines
  • Habitat destruction ~ due to deforestation, population growth, agriculture
  • Bushmeat trade ~ gorillas are killed for the bushmeat trade which is the biggest threat to gorillas. There is a huge demand for bushmeat as it is considered to be prestigious meat amongst the wealthy and elite.  Habituated gorillas do not fear humans and are easy targets for hunters. Meat from one gorilla provides great opportunities for selling.
  • Accidental death ~ killed accidentally in steel traps set in forests for other bushmeat (pigs, wild boars).
  • Disease: Ebola is a serious disease for gorillas and often fatal which has had a significant detrimental impact on the gorilla population.  It is estimated that one-third of the gorilla population died, due to Ebola in 2003. Gorillas are also susceptible to other human diseases, for example; respiratory diseases, scabies, tuberculosis, and other humans to animal transmissible diseases. 
  • Civil unrest, lack of governance, weak law enforcement, lack of local law surrounding gorilla habitats, untrained guards. Gorilla body parts fetch large sums of money.  Many of the poachers are actually guards that are supposed to protect the gorillas.
Mountain gorilla infant closely guarded by its mother, Bwindi National Park, Uganda
Mountain gorilla infant closely guarded by its mother, Bwindi National Park, Uganda
Conservation
  • WWF, and a number of other organisations, and governments are working hard towards gorilla conservation. Conservation efforts are implementing safe and protected areas. 
  • Ecotourism: provides financial support for protecting gorillas in their habitats and helping local people provide protection for their local wildlife. 
  • Monitoring population: research on the distribution and population helps to monitor health and safety. Training guides and rangers to identify any potential issues and report them.
  • Preserving habitats: protecting gorilla habitats by not allowing any deforestation, hunting by local people in search of bushmeat to feed their families, and also poachers from entering their habitats. 

Young mountain gorilla infant, Bwindi National Park, Uganda
Mountain gorilla, Bwindi National Park, Uganda
References

https://www.worldwildlife.org/species/gorilla

https://www.livescience.com/31397-gorillas-subspecies-images.html

https://www.discoverwildlife.com/animal-facts/mammals/facts-about-gorillas/

https://www.iucn.org/news/species/201609/four-out-six-great-apes-one-step-away-extinction-–-iucn-red-list

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