Gorillas by the Numbers
- October 7, 2014
- Posted by: Africa Safaris
- Category: Travel News
MWEZA’S DEATH HAD lowered the Virunga population by one. How many more gorillas had fallen to poachers? How many had been born since the last census five years earlier? How many still survived? These were some of the very basic-questions that bill’s census was supposed to answer.
The February census of Mt. Karisimbi- interrupted by malaria-found only fifteen gorillas in two groups. This was very disappointing given karisimbi’s massive size and ample habitat. The next target was the gorilla rich core area of Mt. Visoke. The composition of the two main research groups was well known, but before moving on to the completely unhabituated population we needed to confirm the number of the three peripheral groups closer to karaoke. These families were not followed on regular basis, but occasionally interacted with group 4&5. If these interactions involved a transfer of a female, as in the case of Liza, bill would usually set off with a tracker to follow and identify the group, and confirm the presence or absence of the female in question. For the census, though, we needed more rigorous attention to group numbers and composition.
Nunkie was one of the gorilla great success stories. He first appeared on the slopes of northern Viscose as a lone silverback in 1972. Over the next five years he settle in a small area of ragged terrain almost directly above the research camp, squarely between the larger home ranges of group 4&5. Whatever Nunkie may have lucked in preffered habitat, he seemed to make up for in personal magnetism. As of 1978, he had attracted at least four females- two from group 4 and his highly vocal copulatory binges were a matter of record. So were three young infants. Nunkie seemed to have secured his place on the mountain by occupying a less desirable range at the upper limit of the forest zone. He rarely ventured below ten thousand feet and thus had no access to the choice bamboo stands at lower elevations. His home range of steep slopes and ravines provided protection, however, as well as ample food supplies of celery, thistles nettles, and thick clumps of preferred Vernonia shrubs.
Approaching Nunkia’s group in 1978 was always something of an adventure. Clambering over some ridge or into a rocky cleft, bill never knew who he would meet first; a calm female like papoose or petula –transfers from group 4 who would tolerate his close presence – or a minimally habituated transfer from a completely wild group. If the latter, her screams were certain to being a swift response to Nunke. Crashing through the undergrowth, he would soon appear in massive full strut, pursing his lips and swatting at any nearby vegetation as he displaced his gaze first to one side, then the other. Nunke had never made his peace with the presence of white apes.
For the census, bill was fortunate to first encounter papoose and her two year old N’Gee as well as a nearby group 6 transfer, Pandora. In their company, he sat in relative calm and counted a total of eight individuals including an only slightly affronted Nunkie. Completing the census work however required leaving the family to do a series of at least three successive nest counts. Only in this way could we get the most accurate count possible due to several helpful aspects of mountain gorilla behavior and biology.
As gorillas move through their range they spend each night in a different location. each of these sites, every gorilla above the age of three to three and a half constructs his or her own “nest” by loosely weaving a blend of plants stems, vines and leaves into a bowl-shaped sleeping platform. Infants sleep in their mothers nest up to the age of three or until the next infant is born. Even more conveniently mountain gorillas usually defecate in the bottom of their nests during the night or early morning. It is believed that the dry, warm dung provides added insulation from the night time chill. The result is a store of information for census workers. Silver backs are readily identified by their significantly larger dung as the abundant presence in the nest of white and gray hairs. Sub adults from six months to eight to eight years old can be quite accurately aged according to relative dung size. Further distinctions can be made among adults, since the presence of both infant and adult dung in a nest indicates that the adult is a female rather than an immature male. In the case of Nunkie’s group, this information provided unambiguous repeated counts of eight individuals, one silver back, four females and three infants. This count stood as two return visits to the group failed to provide visual evidence of a new born infant who might not yet produce solid dung. Nunkie had done well indeed.
The next census target was another peripheral group that occupied an equally rugged range on the Eastern slopes of Visoke. Whereas Nunkie had a reputation as Nguvu powerful group 6;s silver back, Brutus was simply known as kali –nasty. Bill had encountered an agitated Brutus once before when Pablo’s mother Liza transferred to his band from group 5.Bill would learn firsthand just how nasty he could be at later date ,but his contact of May 27 as recorded in his field notes was enough to confirm conventional wisdom.
Coming over a small rise at 11.45, 1 fined Brutus 5m away. He screams twice and retreats through a bush tunnel. Members of the group are heard descending into the ravine beyond. Brutus wraagh at 11; 50….At 11.54 I believe Brutus has followed others and I enter the tunnel while inside, Brutus screams and charges to 4m.This is repeated at 11:57 to within 2.5m,terminated with a sweeping vege swat. I retreat and wait for evidence that Brutus is no longer guarding the other end of the tunnel….at 12:12 I crawl through without mishap.
Tunnels were to be a recurring theme in bill’s relationship with Brutus over the next two years. On that day through the young silver back moved his group across the ravine and sat calmly in full view on the other side for more than an hour. Bill counted six individuals during this visual contact, and then confirmed a total of eight from a series of nest counts. This was a decrease of three adults at least two of them females, since last count four months earlier by Ian Redmond. Such a loss from natural transfers might at least partly account for Brutus’s agitated state. It also raised concerns of poaching deaths in a home range that was close to human settlements outside the park.
The day after finishing the group 6 nests counts, bill moved on to the last peripheral contact. Peanuts had been known by Karisoke researchers for many years first as black back in the since disbanded Rafiki group, then as leader of his own group with multiple females. In late 1977,peanuts was badly beaten in a fight with another silver back, who took his females and left him so severely wounded that Dian though he would die. He survived though and continued his solitary patrols on Visoke’s lower slopes, no doubt hoping to again attract some females. On May 28, Bill approached peanuts to see if he had succeeded, perhaps with some of the missing group 6 members.