Mountain gorillas are endangered because of a combination of habitat loss, accidental snaring, infectious diseases caught from humans, armed conflict in their range, and a gene pool so small it limits their ability to adapt. Their total wild population has crossed 1,000 individuals for the first time on record, but they remain confined to just two isolated pockets of forest in central Africa, surrounded by some of the most densely populated rural land on Earth.
Habitat Squeezed by Human Settlement
Mountain gorillas live only in two locations: the Virunga Massif, a chain of volcanoes straddling Rwanda, Uganda, and the Democratic Republic of Congo, and Uganda’s Bwindi Impenetrable Forest. The land surrounding the Virunga Massif supports rural human population densities as high as 820 people per square kilometer. That kind of pressure leaves gorillas with nowhere to expand.
Forests are cleared for farming, firewood, and settlement right up to the park boundaries, creating a hard edge between gorilla habitat and human activity. Unlike species that can migrate to new territory when resources thin out, mountain gorillas are trapped in these highland forests. Their habitat is essentially an island of green surrounded by agriculture, and any reduction in forest area directly reduces the number of gorillas the land can support. The very first complete census of Virunga gorillas, conducted in 1971, counted 275 individuals. By a decade later, habitat destruction and poaching had driven that number down to 254.
Snares Set for Other Animals
Poachers in the region typically set wire and rope snares to catch antelope and other bushmeat species. Mountain gorillas stumble into these traps by accident. Adults can sometimes break free, but the wire often remains embedded in a hand or foot, causing infection, tissue death, or permanent disability. Infants and juveniles are especially vulnerable because they lack the strength to pull loose.
Data from Rwanda’s Volcanoes National Park show that wildlife veterinarians treated 37 gorillas specifically for snare entrapment injuries over the monitoring period, alongside 95 gorillas for other conditions including trauma and respiratory illness. Anti-poaching patrols now sweep gorilla habitat to locate and destroy snares before animals encounter them, and this effort has been one of the most direct contributors to the population’s recent recovery.
Human Viruses That Jump to Gorillas
Because gorillas share roughly 98% of their DNA with humans, they’re susceptible to many of the same respiratory infections. This is not a theoretical risk. Respiratory illness is the second leading cause of death in mountain gorillas after physical trauma, accounting for about a quarter of investigated deaths. Infants are hit hardest.
In 2009, a human metapneumovirus outbreak sickened 11 of 12 members of a single gorilla family group in Rwanda and killed two of them. Between 2012 and 2013, researchers confirmed that human respiratory syncytial virus (the same virus that causes RSV in children) was circulating in gorilla groups during outbreaks of coughing, sneezing, and nasal discharge. Twelve of 20 fecal samples from sick gorillas tested positive for the virus. Samples from healthy gorillas did not. The evidence is clear: people are repeatedly introducing respiratory pathogens into gorilla populations, likely through tourism, research, and nearby community activity.
For young gorillas under about three and a half years old, these infections can be especially severe, mirroring the pattern in human children under five. This makes every cough from a park visitor or ranger a potential threat to the species.
Armed Conflict in Gorilla Territory
The eastern Democratic Republic of Congo has experienced decades of war and civil unrest, much of it centered in and around Virunga National Park. Rebel groups, government soldiers, and armed militias have all operated inside gorilla habitat. During periods of active fighting, park rangers become the only government presence in the area, which makes them direct targets. Rangers have been killed in ambushes, and at times entire sections of the park have been inaccessible for months.
During one period of conflict involving the M23 rebel group, rangers were unable to monitor the gorillas for four consecutive months. When the front lines of battle swept through gorilla territory, the animals were caught between armed forces on high alert. Some gorillas died in crossfire during the civil wars of 1996 and 1998. Beyond direct violence, armed groups exploit the park’s natural resources illegally, degrading the habitat gorillas depend on. The instability also disrupts the tourism revenue that funds conservation, creating a cycle where conflict undermines the very programs keeping gorillas alive.
A Dangerously Small Gene Pool
Genome sequencing has revealed that mountain gorillas carry the scars of a population decline stretching back roughly 100,000 years. Their genetic diversity is two to three times lower than that of western lowland gorillas. On average, 34.5% of a mountain gorilla’s genome is homozygous, meaning both copies of each gene are identical. That level of inbreeding exceeds even the most inbred human populations ever studied.
This matters for two reasons. First, low diversity at immune system genes reduces the population’s ability to fight off new or evolving pathogens. Second, while the small population has actually purged some of the most harmful genetic mutations over time (a natural consequence of inbreeding), it still carries an increased overall burden of mildly harmful genetic variants. These don’t kill individuals outright but can reduce fertility, immune function, and resilience to environmental stress. A single new disease or sudden habitat change could have outsized consequences for a population this genetically uniform.
How Conservation Pulled Them Back
Despite all of these pressures, the mountain gorilla is one of the few large primates whose numbers are actually increasing. The population in the Virunga Massif grew from 480 individuals in 2010 to 604 in the most recent census, pushing the global total past 1,000. In 2018, the IUCN downgraded the species from Critically Endangered to Endangered, a rare piece of good news on the Red List.
That recovery rests on several coordinated efforts. Daily anti-poaching patrols remove snares and deter illegal activity. Veterinary teams intervene directly when gorillas are injured or ill, performing field treatment that would be unthinkable for most wild species. Community engagement programs channel tourism revenue into local infrastructure, including employment as guides, porters, and rangers, and projects like rainwater harvesting tanks that reduce the need for communities to enter gorilla forest for water. The International Gorilla Conservation Programme has helped establish community-owned ecolodges, tying the economic survival of neighboring villages to the survival of the gorillas themselves.
The species remains endangered because 1,000 individuals in two isolated forests is still a razor-thin margin. A single severe disease outbreak, a new wave of armed conflict, or continued habitat pressure could reverse decades of progress. The same factors that brought mountain gorillas to the edge of extinction have not disappeared. They’ve simply been held in check by one of the most intensive conservation campaigns ever mounted for a single species.