Dispersed gorillas located through census genetic analysis


June 4, 2018


Media contact: Dr. Erika Archibald, earchibald@gorillafund.org; 678-612-9019; 404-624-5881

Media photos:  https://www.dropbox.com/sh/ymeswfcdpqpo3av/AADUMNPJanVgGZGqGmkyaKXHa?dl=0


Dispersed gorillas located through census genetic analysis

The mountain gorilla census results just released not only showed an increase in their population to 604, up from 480 in the 2010 census, but also provided information about gorillas who had left the monitoring areas some years ago, joining groups that are not habituated to the presence of humans and thus not followed by trackers, researchers or park authorities.

Luckily, the census process included genetic analysis, obtained from fecal samples from all the gorilla nests found in all three countries where the Virunga mountain gorillas live – Rwanda, Uganda and the Democratic Republic of Congo. From the fecal samples, scientists are able to extract DNA information, which provides positive identification of individual gorillas, and prevents any double counting. This information also allows us to understand the genetic variability in the population.

Even more exciting, the genetic analysis also helped us to localize individual gorillas who are no longer in the groups that are monitored every day. These gorillas had emigrated to non-monitored groups at various times, and so we have not been able to track them since they left.

Many of the Fossey Fund’s trackers and researchers remember these gorillas quite well, from the time when they were in our monitored groups. Felix Ndagijimana, who is the Fossey Fund’s Director of Rwanda Programs and the Karisoke Research Center, started with the Fossey Fund as a research assistant in 2004 and remembers Gufasha well.

“One of the first events that I witnessed when I was working as research assistant was the transfer of Gufasha from her natal group,” Ndagijimana says. “She was only 7 years old at the time and it was hard for her to get settled in the new group – a young silverback was targeting her quite aggressively for mating. She then moved to a non-habituated group in Congo and we lost her track. In the 2010 census we learned that she was still in Congo, and now once again, it has been confirmed that she is still there. And now is 20 years old!”

Makuba and Mawingu – now 29 and 36 years old – come from two different natal groups, but both joined Beetsme’s group in 2007. Since then they have been together supporting each other during several moves, including a brief one to the lone silverback Umushikirano, before moving to a non-monitored group in Congo, where the current census located them.

“The fact they are still there is both wonderful and reassuring, as they evidently find in each other a great alliance,” says Fossey Fund Gorilla Program Senior Advisor Veronica Vecellio.

The Fossey Fund has also recently documented the disintegration of some gorilla groups due to the death of the dominant silverback, which causes the females to disperse and find other groups. For example, females Kanama and Sabato moved out of our tracking range after the death of silverback Gushimira. Staff were relieved to learn via the census that they are fine, especially since Sabato was only 5 years old at the time of this dispersion.