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.
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 4th April 2016.
“
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.