In Gombe National Park, one of the world’s most famous chimpanzee populations has fallen by nearly 50 percent since the 1960s, raising concerns among conservationists about the future of a species that transformed humanity’s understanding of itself.
Authorities estimate that only about 77 chimpanzees remain in Gombe today, down from roughly 150 when Goodall arrived in 1960 and began the observations that would forever change the study of animal behavior.
It was here that Goodall documented chimpanzees making and using tools, a discovery that challenged the belief that toolmaking was uniquely human and blurred the line separating humans from their closest living relatives.
More than six decades later, the bloodlines of those pioneering chimpanzees survive.
But they now inhabit a shrinking and increasingly isolated world.
“Long-term monitoring reveals a population that has experienced both resilience and vulnerability,” said Tanzania National Parks (TANAPA) Veterinary Specialist Dr. Jane Mwandupe.
The decline has been gradual but persistent.
According to TANAPA records, the population stood at 88 chimpanzees in 2016 before rising briefly to 94 in 2017.
Numbers then trended downward, reaching 84 in both 2020 and 2021, 85 in 2022, 83 in 2023 and approximately 77 in 2024.
The figures highlight mounting pressures on one of the world’s most intensively studied wild chimpanzee populations.
Covering just 33.6 square kilometers along the shores of Lake Tanganyika, Gombe is renowned as one of the most important field sites in the history of animal behavior research.
Within its forests, scientists documented chimpanzees hunting cooperatively, forging alliances, defending territories, nurturing offspring and exhibiting complex social behavior once thought exclusive to humans.
Today, however, researchers face a different question: whether such a small and isolated population can withstand growing environmental and biological pressures.
One of the strongest indicators of the decline is the collapse of the Kalande chimpanzee community.
Once a recognized social group within the Gombe ecosystem, Kalande has been reduced to only a handful of surviving individuals.
Dr. Mwandupe said conservationists link much of the decline to the long-term impacts of Simian Immunodeficiency Virus (SIV), which affected the community during the 1990s, combined with recurring outbreaks of respiratory disease.
“The remaining females have increasingly integrated with neighboring communities, leaving the former Kalande range largely unoccupied,” she said.
Disease remains the single greatest threat.
Between 2020 and 2024, researchers recorded 20 chimpanzee deaths in and around the park.
Most were associated with infectious diseases, particularly respiratory illnesses.
Others resulted from territorial clashes between rival chimpanzee communities, while some deaths could not be conclusively explained.
Historical records from Gombe show that more than half of documented chimpanzee deaths have been linked to disease, while about one-fifth have resulted from inter-community conflict.
Scientists believe the park’s small size may intensify both risks by increasing contact between animals and increasing competition for territory and resources.
Yet amid the losses, researchers have identified signs of resilience.
Between 2020 and 2024, 21 chimpanzee births were recorded across the park, most within the Kasekela and Mitumba communities.
Dr. Mwandupe noted that female chimpanzees reproduce slowly, typically giving birth only once every four to six years.
“As a result, every surviving infant represents an important contribution to the future recovery of the population,” she said.
The births suggest the population retains the biological capacity to recover if conservation efforts succeed.
That challenge extends beyond the park’s boundaries.
Surrounded by expanding human settlements, farms and fragmented forests, Gombe has become increasingly isolated from other chimpanzee habitats.
Conservationists view the Gombe-Kagunga corridor, a network of village forests connecting fragmented landscapes, as critical to maintaining genetic diversity.
An estimated seven chimpanzees currently inhabit the corridor.
Without it, scientists warn, Gombe’s chimpanzees face growing genetic and ecological isolation.
TANAPA Chief Conservation Commissioner Musa Nasoro Kuji said authorities have prioritized protecting the corridor and improving habitat connectivity.
“The government authorities have repeatedly stressed the importance of strengthening legal protection for the corridor and ultimately incorporating it into the wider protected-area network,” Kuji said.
Conservation efforts now include daily monitoring of chimpanzee health and behavior, biannual surveys in the corridor, disease surveillance, habitat protection, fire prevention, climate and vegetation monitoring, visitor health controls and environmental education programs.
Local communities have become a central pillar of the strategy through alternative livelihood initiatives aimed at reducing pressure on forests.
Among the most successful are beekeeping projects involving hundreds of hives in villages surrounding the park.
Authorities have also stepped up enforcement against illegal encroachment.
A major operation in 2025 led to the demolition of 97 unauthorized structures, the destruction of 12 livestock enclosures and the arrest of 12 suspects. Officials said approximately 75 percent of those detained were foreign nationals.
