Populations of World's Largest Gorilla Decline by 77 Percent

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August 30, 2016 | 4,947 views

Story at-a-glance

  • Numbers of Grauer’s gorillas, the world’s largest primate, dropped dramatically, from 17,000 in 1994 to 3,800 in 2016
  • Human conflict in the Democratic Republic of Congo has led to many gorilla casualties
  • Guerrilla fighters occupying the area may kill gorillas for food, as may workers at illegal mining operations (for coltan, a mineral used in the manufacture of mobile phones)

By Dr. Becker

Grauer’s gorilla, also known as the Eastern lowland gorilla, is the world’s largest primate. These great apes can weigh up to 400 pounds and live only in the eastern Democratic Republic of Congo (DRC).

Unfortunately, war in the region has taken a toll on the gorillas. A recent report by the Wildlife Conservation Society (WCS) and Fauna & Flora International revealed their numbers have dropped dramatically, from 17,000 in 1994 to 3,800 in 2016.1 That’s a 77 percent decline.

The numbers are only approximations, since Grauer’s gorillas live in remote jungle regions and are difficult to track. Violence in the area has made gorilla research even more difficult.

For the current report, the researchers recorded gorilla nests and tracks, and used statistical analyses to estimate their current numbers.2 Chimpanzees in the area are also being affected. The researchers estimated that their population decreased up to 45 percent since 1994.

Grauer’s Gorillas Become Victims of War

Human conflict in the DRC has led to many gorilla casualties. Guerrilla fighters occupying the area may kill gorillas for food, as may workers at illegal mining operations (for coltan, a mineral used in the manufacture of mobile phones).

War has also resulted in deforestation that threatens the gorillas’ ability to survive in the area.3 It’s an extremely volatile situation that’s taken human lives as well, including in the Kahuzi-Biega National Park, a protected wildlife sanctuary.

Within this protected area, numbers of the gorillas rose from 130 to 181 from 2000 to 2010, a significant success considering the rapid declines elsewhere. Park rangers help to patrol and protect the area, but at least one guard was killed by rebels in an ambush.

Radar Nishuli, chief warden at Kahuzi-Biega National Park and co-author of the recent report, told The Guardian:4

“What we have found in the field is extremely worrying. We are urging a strong and targeted response that addresses the following: Train, support and equip eco-guards to tackle poaching more effectively; build intelligence networks, and support the close daily monitoring of gorilla families to ensure their protection; engage customary chiefs who hold traditional power in the region to educate their communities to stop hunting these apes.”

Grauer’s Gorillas Occupy Only 13 Percent of Their Historical Range

Grauer’s gorillas, which have a stocky body, short muzzle and large hands, eat mainly fruit and other vegetation. Sadly, their range in which to find food and make nests has decreased from 8,100 square miles to about 4,100 square miles.

It’s though the gorillas now occupy an area that’s just 13 percent the size of their original historical range.5 Until recently, violence in the area made it virtually impossible for the area to be monitored, which is why the status of Grauer’s gorillas has remained unknown since the 1990s.

Researchers from WCS gained access to the area in 2011 and were able to collect the data for the recent report, which shows the animals are in great need of urgent protection.

Gorillas at Risk of Disappearing

If the Grauer’s gorilla population declines continue at the current rate, they could disappear from most of their native habitat within just two to five years, according to the report.

The International Union for Conservation of Nature and Natural Resources (IUCN) Red List currently lists the gorillas as endangered, but the authors of the new report suggest they should be relisted as “critically endangered,” which would provide more opportunities for funding and protection.

IUCN justifies the gorilla’s current classifications as follows, noting the steep populations declines due to causes that “are not easily reversible”:6

“Due to high levels of exploitation, and loss of habitat and habitat quality as a result of political unrest and expanding human activities, this subspecies is estimated to have experienced a significant population reduction in the past 20 to 30 years … and it is suspected that this reduction will continue for the next 30 to 40 years.

The maximum population reduction over a three-generation (60-year) period from the 1970s to 2030 is suspected to exceed 50 percent, hence qualifying this taxon for Endangered …

The causes of the reduction, although largely understood, have certainly not ceased and are not easily reversible.

The suspected future continuation of the population reduction is based on a precautionary approach taking into account the rapidly increasing human population density in the region and the high degree of political instability in the range states.”

Is There Hope for the Future for Grauer’s Gorillas?

In addition to changing the gorillas’ classification from endangered to critically endangered on the IUCN’s Red List, the authors of the report recommended several policy changes and other initiatives that could help to protect Grauer’s gorillas, perhaps enough for their populations to make a comeback. Among them:7

Unfortunately, most large herbivores, gorillas included, have already disappeared from North America and Europe, and now are mostly found only in pockets throughout southern Asia, Southeast Asia and Africa.

Most all of their threats are human-induced; a radical, concerted intervention to stop poaching, manage protected areas and conserve habitat and remaining populations will be necessary to save these incredible species.

[+]Sources and References [-]Sources and References

  • 1 Wildlife Conservation Society April 4, 2016
  • 2, 7 Discover April 25, 2016
  • 3, 4 The Guardian April 5, 2016
  • 5 World Wildlife Fund, astern Lowland Gorilla
  • 6 The IUCN Red List of Threatened Species, Grauer’s Gorilla