Mountain Gorilla Census Begins in Uganda, Rwanda and DR Congo - Gorilla Tourism News

Have you ever heard about Gorilla trekking or wondered how many mountain gorillas do exist in East Africa? Well, you are not alone! Many people are probably unaware of how many of these primate cousins and very valuable tourist attractions there are and how their numbers are determined.

Every after five years, a gorilla census is carried out in the Virunga massif – which is a combination of Mgahinga Gorilla National Park in Uganda, virunga national park in DR Congo and Volcanoes National Park in Rwanda – all together forming the Virunga conservation area.

The 2015/2016 mountain gorilla census is already underway under the umbrella of the Greater Virunga Trans boundary Collaboration (GVTC), with the work being done by Rwanda Development Board (RDB), I’ Institut Congolais pour la Conservation de la Nature and Uganda Wildlife Authority (UWA)

The last mountain gorilla census was carried out in 2010, indicating an estimate of 480 gorillas living in social groups – also known as families and 14 long haired silverbacks (solitary mature male gorillas). Another census carried out in 2011 in Bwindi Impenetrable National Park, indicated there were 400 gorillas and 16 silverbacks.

Silverback with a baby Gorilla in Volcanoes National Park - Rwanda

Belise Kariza, chief gorilla tourism officer with RDB, says the first round of the census that began in October 2015 was a success. “The second phase will be mainly about strengthening the accuracy of the first phase, getting the demographics which include age and sex ration, the size and numbers of groups, and the surrounding vegetation and water sources in comparison with the human activity in the area”.

In the previous census, the numbers were arrived at by estimate but 2015/2016 census is being carried out using advanced technology and DNA samples. “The census results, which will be released in 2017, are a best indicator of the benefits in terms of security, research and environmental health dividends obtained through the GVTC”, says Dr Muamba Tshibasu Georges, executive secretary, GVTC, adding that due to the collaboration, security in the Virunga massif has increased, leading to normal reproduction rate of the gorillas.

A healthy gorilla population is also the result of collaborations between governments and NGOs. Jossy Muhangi, the public relations manager, UWA, says, “Gorilla doctors have researched on the diseases that affect both humans and gorillas and are coming up with vaccines for those visiting the gorillas”.

Last week, the Uganda cabinet also approved the Uganda wildlife bill 2015 that brings forth stiffer penalties for wildlife crimes in terms of fines and jail terms. Conservation efforts by GVTC also include establishing schools and water sources in communities around the Virunga Massif to do more towards conservation efforts.

How the Gorilla Census is done

Joseph Arinaitwe, an ecological monitoring and research ranger with UWA in Bwindi Impenetrable National Park, says that the gorilla numbers in the Virunga Massif are now estimated to be at 800. A new group of data entrants currently on training, entered the forest on 4^th April 2016.

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The census is generally a sweep from one side of the forest to another” says Arinaitwe adding; “we are starting on the southern part of the massif in Rwanda, and will end on the Ugandan side. There will be different teams in the forest, in constant communication with each other”. Gorilla census begins with the individuals following a gorilla trail until they locate a nest site. Every evening, gorillas make a nest in which to sleep and they never return to those nests.

“Even if they return to the same site, they will make a new nest next to the old one. Each nest contains one gorilla and we consider it used when we find gorilla dung in it”. The first duty after finding a gorilla nest site is to establish how old it is. If it is older than five days, then it is useless because most of the DNA is gone.

“One site can have many nests, so we label each nest with a small piece of paper. Then, we wear protective gloves and begin establishing the size of the dung”. Depending on the size of the dung, the data collectors can conclude, using age classification strata, whether an adult male, medium range or baby gorilla was in the nest.

“Dung measuring 7.2cm, with silvery hair in it, means an adult male gorilla (silverback) slept in the nest. Other dung is classified a medium size, though not specifying the sex.” While measuring the dung, the sample collector has to ensure that his gloves do not touch it because that particular DNA can be transferred to other dung, thus making it hard for the laboratory to have conclusive findings. 

Also, sample collectors are not allowed to speak while holding the dung because their saliva can mix with the Gorilla’s DNA. After measuring the dung, a sample of it is placed in a tube containing ethanol. The tube is then transferred to a Ziploc bag.

“Ethanol helps to preserve the sample for an average of 24 to 30 hours before transferring it to another sample tube containing silica to keep it dry. The laboratory analysis to establish the individual DNA of the gorillas is done in an American lab.”

After collecting data samples from one gorilla site, the team follows the gorilla trail to look for more nesting sites. “From at least three consecutive nest sites, you can tell the average number of the gorillas in that particular group/ family. If the first site had 19 nests, the second one might have slightly less or more and it is important because what you missed in the previous site can be found in the next one.”

Once the team has collected a good number of samples, it is shipped out of the forest for safer storage until the whole exercise is completed and the samples will be transferred to the USA.