Without room to expand, mountain gorillas’ population growth could backfire
Mountain gorilla populations have grown steadily in recent decades, thanks largely to intensive conservation efforts in Rwanda, Uganda and the Democratic Republic of Congo. But the species’ entire population is confined to protected parks in these countries, with limited room to expand, and as the population has grown, so too has population density. A new study that tracked the incidence and intensity of parasitic infections across the mountain gorilla’s range suggests that greater population density correlates with greater susceptibility to parasites and other health problems.
The mountain gorilla (Gorilla beringei beringei) is a subspecies of the eastern gorilla and is found in five protected areas in DRC, Rwanda and Uganda. Image by Rhett Butler for Mongabay.
Mountain gorillas, one of the world’s endangered apes, appear be facing a fresh health threat after a successful conservation campaign saved them from looming extinction, a new study says.
Thanks to intensive conservation efforts, the population of mountain gorillas (Gorilla beringei beringei) has risen to more than 1,000, up from 620 in 1989, according to the International Union for Conservation of Nature. As a result, in 2018 the organization changed the conservation status of mountain gorillas from critically endangered to endangered.
However, the habitat available to mountain gorillas has not expanded in tandem with population growth. The entirety of the species is confined to parks in Rwanda, Uganda and the Democratic Republic of Congo. Bounded by human settlements, the gorillas are unable to expand beyond these protected areas, leading to increasing population density.
The study, led by biologist Klára J. Petrželková of the Czech Academy of Sciences, found that as the mountain gorilla density increased, populations have become more susceptible to health problems.
After gastrointestinal diseases were reported in the primates, researchers examined the prevalence of two parasitic worms (helminths) — strongylids and tapeworms — and found the pattern of infection appears to be influenced by the age, location and group size of the gorillas.
The findings, which the authors of the report say point to possible “side effects” of the conservation success, are expected to guide future conservation efforts and academic studies on gorillas.
- Petrželková, K. J., Uwamahoro, C., Pafčo, B., Červená, B., Samaš, P., Mudakikwa, A., … Modrý, D. 2021: Heterogeneity in patterns of helminth infections across populations of mountain gorillas (Gorilla beringei beringei). Scientific Reports 11: 10869. [IF=3.998] doi:10.1038/s41598-021-89283-4
