Western Lowland Gorillas—New research on their social structure and possible implications for the transmission of ebola virus

It is good to see old friends in print. This time it is the Western Lowland Gorillas we were privileged to visit and watch at Ngaga in the Odzala-Kokoua National Park of the Republic of Congo (Congo, Brazzaville) nearly five years ago (see my post of 18 August 2014).

We visited two groups just a few miles apart and it is the interactions that occur between the three group in the immediate vicinity of Ngaga that is the subject of a paper just published in Proceedings of the Royal Society.

I cannot overemphasise the enormous amount of work that went into this study done between 2013 and 2017. Behaviour of the groups was monitored on approximately 305 days each year. The trackers (who move at speed through the forest) located the groups each morning. Every individual gorilla can be recognised by the trackers and researchers. Notes were made of their behaviour for an average of two hours per day, itself a difficult undertaking because of the dense vegetation. And the authors do not even mentikon the sweat bees.

The behavioural work was done by Magdalena Bermejo (who heads the whole project in the Republic of Congo) and Germán Illera, with help from the same trackers who took us from the lodge to the groups of gorillas.

In addition to the behavioural observations, gorillas over a wide area were genotyped from samples of their faeces collected from the nests they build and occupy at night.

Previous observations on Western Lowland Gorillas (Gorilla gorilla gorilla) at bais (open grassy clearings often surrounding a body of water) suggested a very different behaviour from the Mountain Gorilla (G. beringei beringei). Groups of the former met without aggression—in marked contrast to encounters between group of the latter. In Ngaga, an area without bais, these observations were not only confirmed those but indicated a dynamic community structure. In the words of the authors:

Both approaches revealed a social system much more dynamic than anticipated, with non-aggressive intergroup encounters that involved social play by immature individuals, exchanges of members between groups likely modulated by kinship, and absence of infanticide evidenced by infants not fathered by the silverback of the group where they were found. This resulted in a community composed of groups that interacted frequently and not-aggressively, contrasting with the more fragmented and aggressive mountain gorilla (G. beringei beringei) societies. Such extended sociality can promote the sharing of behavioural and cultural traits, but…

The but refers to the disease that has devastated local gorilla and human populations, including the area studied—ebola. The authors make the point that interaction between groups could promote the rapid transmission of the virus:

Social behaviour may thus have greatly contributed to the massive impact of past Ebola outbreaks that have resulted in an increase of the threat level for the species, raising major conservation concerns about population declines in the future. Understanding group dynamics in social species is of utmost importance when coming to model the transmission of pathogens such as Ebolavirus. However, since the high mortality imposed by outbreaks is likely to select against this social behaviour, its persistence in W[estern] L[owland G[orilla] implies that either such massive die-offs may have been rare in the past, or that the associated benefits outweigh the disadvantages. In any case, the peculiar social behaviour of western lowland gorillas is an outcome of its evolutionary history and will definitively impact its fate.

I do wonder though whether the dynamic social structure and outbreeding may actually ensure a higher degree of immunocompetence of individuals. In other words, and turning the argument round, whether the social structure is actually protective to individuals exposed to potentially lethal infections.

Here is a link to the video included in the paper.

And here  again are my videos of the gorillas at Ngaga:

Forcina G, Vallet D, Le Gouar PJ, Bernardo-Madrid R, Illera G, Molina-Vacas G, Dréano S, Revilla E, Rodríguez-Teijeiro JD, Ménard N, Bermejo M, Vilà C. 2019. From groups to communities in western lowland gorillas. Proceedings of the Royal Society B 286: 20182019. http://dx.doi.org/10.1098/rspb.2018.2019 

Ebola: Gorillas and other wild animals

Female gorilla in the Jupiter Group
Ngaga Camp,
Republic of Congo, May 2014
Her toddler was clambering in the trees
above her

The conversation at the funeral of a former colleague with another former colleague, a microbiologist with wide interests who I had not seen for some years, turned to the outbreak of ebola virus (EBOV) in West Africa and how it may spread between wild, domesticated and human mammals, and the characteristics needed for one or more reservoir species, in other words, those that carry but do not suffer to the point of rapid mortality the infectious agent.

In May we were at the site of the 2003 outbreak in the Republic of Congo and heard of the devastating effect ebola had on the Western Lowland Gorilla population. Since returning I have had the chance of catching up with the literature on that outbreak and how it was established that ebola has such a devastating effect on the survival of gorillas, with a mortality rate of 90-95% and the estimated loss of 5000 gorillas from a relatively small area.

Magda Bermejo who lives at the camp in the Republic of Congo we visited (see post of 18 August 2014) after the effective loss of her study groups at Lossi to the ebola outbreak, established the death of gorillas and chimpanzees during human outbreaks, found ebola virus in a number of the carcasses and showed an apparent passage from group to group of gorillas rather than independent transmission form a putative reservoir species. But then, and apart from the enormous potential effect on survival of the great apes in Africa, all sorts of question arise as to who or what becomes infected first and how does the infection (not that easily transmitted according to the evidence with contact through body fluids being needed) pass between groups.

Bushmeat has been implicated as the initial source of human infection while bats, particularly, but also duikers, pigs and domestic dogs are suspected as possible reservoir species. Recently, I see those sequencing the virus collected during the current outbreak have found rapid changes and are reaching different conclusions on the origins of EBOV. The article by Gretchen Vogel in Science (29 August 2014) reads:

Some researchers theorized, based on early sequencing data, that EBOV had circulated for decades, undetected, in animals in the region. But the new analysis, strengthened by the unprecedented number of genomes, supports another theory: that the virus spread, via animal hosts, from Central Africa within the last decade. Researchers aren’t sure which animal to blame, but fruit bats are their leading suspects (Science, 11 April, p. 140). At least one fruit bat species known to carry ebolavirus has a population range that stretches from Central Africa across to Guinea.

That more research on ebola and much more money to fund that research are necessary are truisms. The dangers to those working in a human outbreak to collect samples in areas where facilities for the safe care of patients and basic hygiene are poor also cannot be overestimated. Five of those who collected samples for sequencing  in the current human outbreak have died. Until really hard evidence is obtained from extensive surveys in wild (and domestic) animals over meaningful periods of time and over a wide geographical area, speculation and soft epidemiological evidence may have to suffice in the meantime. But, in that meantime and beyond, alongside local outbreaks that devastate human populations, the great apes of Africa are at risk.

Tom, our former colleague, would I am sure have been delighted that his funeral was the occasion for several coffee-room type discussions on science and science politics; Scottish politicians were not rated highly in the latter.

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Useful starting points for further reading:

Bermejo M et al. Ebola outbreak killed 5000 gorillas. Science 314, 1564
Vogel G. 2014. Are Bats Spreading Ebola Across Sub-Saharan Africa? Science 344, 140
Vogel G. 2014. Genomes reveal start of ebola outbreak. Science 345, 989-990
Walsh PD et al. 2003. Catastrophic ape decline in western equatorial Africa. Nature 422, 611-614
Wittmann TJ et al. 2007. Isolates of Zaire ebolavirus from wild apes reveal genetic lineage and recombinants. Proceedings of the National Academy of Sciences of the USA 104, 17123-17127

Alfred at Bristol Zoo: What Sort of Gorilla Was He?

When writing the previous post, I must confess to a degree of confusion as to the identity of Alfred, the famous gorilla at Bristol Zoo from 1930 until his death in 1948.

Alfred (from Schomberg's British Zoos)

This is what the fully referenced Wikipedia entry has to say (with my bold):

Alfred was initially found by an Expedition from the American Museum of Natural History, New York and Columbia University in 1928 in what was then Belgian Congo. The expedition members were told that a pair of gorillas had been shot for ‘raiding’ a farmer’s field for food, afterwards a baby was discovered and suckled by a local woman. The baby gorilla was later sold to a Greek merchant and taken to the town of Mbalmayo in modern day Cameroon, where the expedition encountered him playing in the streets. He was described by the Expedition as ‘the liveliest specimen of his kind we had ever seen’.

In 1830 [1930] Alfred was sold to an Italian who, after bringing him to Europe, sold him on to an animal dealer. Bristol Zoo, already successful in rearing chimpanzees, acquired Alfred for £350. Alfred spent a few months housed in Rotterdam in 1930 before continuing to Bristol Zoo. Alfred was reputedly named for Alfred Mosley, a benefactor of the zoo. Although during his life he was thought to be a Mountain Gorilla, it is more likely that he was a Western Lowland Gorilla.

His stuffed skin appears to be that of a Western Lowland Gorilla but I can see how people got confused. This is what Geoffrey Schomberg (1927-1997) wrote in British Zoos (1957):

Bristol Zoo will always be associated with the name of Alfred, the most famous gorilla that ever lived in captivity. When he was only a few months old, his parents were shot raiding while raiding a plantation in the Kivu Mountains of equatorial Africa. He was suckled by a native woman, and passed through the hands of a Greek merchant, an Italian who brought him to Europe, and a Dutch animal dealer, from whom he was purchased by the Zoo on 30 September 1930. He was then two years old and weighed two stone.

If Schomberg’s account was correct, then Alfred would have been a Mountain Gorilla from the Kivu Mountains, well outside the range of the Western Lowland Gorilla. However, contemporary newspaper reports describe a different location for ‘Kivu’. This is the Exeter and Plymouth Gazette of 11 September 1930 (before the date given by Schomberg of Alfred’s purchase):

“Have you seen Alfred.” That is what the people of Bristol are saying to one another…They [gorillas] are very rare and very shy, and are confined to a small area in the Cameroons and the Kivu district on the West Coast of Africa.

Was there a misunderstanding somewhere along the line of his origin, and ‘Kivu’ perhaps assumed to be the mountains of Kivu province in the Belgian Congo (now Democratic Republic of Congo, Congo Kinshasa)? Was ‘Kivu’ a garbled version of a different location as Alfred was passed along the line?

The Wikipedia entry has Alfred Mosley as the zoo’s benefactor after whom the gorilla was named, whereas Hannah Paddon in Sam Alberti’s The Afterlives of Animals spells it Sir Alfred Moseley. I have been unable to find much information on the human Alfred, other than that he may have made his money in South Africa (the gorilla cost the equivalent of about £20,000 in today’s money) and he may have led missions to the USA to examine their industrial and employment methods in the early 1900s.

Has anybody any more information on Alfred’s identity, the gorilla that is?

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Wikipedia entry for Alfred
http://en.wikipedia.org/wiki/Alfred_the_Gorilla
Paddon H. 2011. Biological objects and "mascotism". The life and times of Alfred the gorilla. In Alberti SJMM, The Afterlives of Animals. University of Virginia Press
Schomberg G. 1957. British Zoos. London: Wingate

A Visit to Gorillas in the Congo

One of my earliest memories is of the first non-domestic animal I saw—a gorilla, ’Alfred’ at Bristol Zoo in summer 1946. The snapshot in my brain has the zoo entrance to the left and Alfred’s cage in front of me. My great (grand in genealogical terminology) uncle and aunt and my grandparents are to my left and my parent are to my right. Alfred is dragging a piece of sacking from left to right.

Alfred was an animal celebrity and a source of great pride in Bristol where he lived from 1930 until he died in 1948.

Another gorilla but this time a dead one also made a strong impression on a little boy.‘George’ (I cannot remember his ever been called this in the 1950s) was in the natural history museum at Wollaton Hall. Mounted impressively, upright, hanging on a tree, with his teeth bared and reproductive organs in full view (small remember in the gorilla) he towered above the visitors and this small boy can remember being more than a little scared every time I was taken to see him (probably two or three times a year). George is still there but Wollaton Hall as a natural history museum is a shadow of its former self and confirms my belief that museum display professionals must learn to leave things alone. This gorilla, I read now, was bought by Nottingham Corporation from the 1878 Paris Exposition held to mark the recovery of France from the Franco-Prussian War.

The next time I saw Alfred he was stuffed and on display in the Bristol’s museum, still the cause of great civic pride as recounted by Hannah Paddon in Sam Alberti’s The Afterlives of Animals. That was in 1957. Bristol Zoo went on to have other gorillas in the 1950s and I took photographs of the new accommodation when I went to my last visit to Bristol Zoo in 1963.

Bristol Zoo Gorilla House, 1963

As I wrote in my post of 16 June, the privilege of being able to visit groups of Western Lowland Gorillas and observe the other mammals, birds, reptiles and amphibians in the Congo Basin is an experience of a lifetime. In the middle of May we were with a group of ten clients of Naturetrek in the camps in the Republic of Congo run by Wilderness Safaris, Ngaga and Lango, 340 miles from Brazzaville, both in or adjacent to the Odzala-Kokoua National Park.

At Ngaga we divided into parties of two or four and visited two groups of gorillas, each headed by a silverback, ‘Jupiter’ and ‘Neptune’. These gorillas were habituated by Dr Magda Bermejo and her colleagues. Because of the effects of outbreaks of ebola on the population, the IUCN classification of the Western Lowland Gorilla is 'critically endangered’.

Filming was difficult through the thick vegetation. The camera was often at arms length and liable to shake. However, the footage below also shows the dense Marantaceae foliage, a major source of food for the gorillas, the environment in which they live and the sweat bees they have to put up with. What the video does not show is a female gorilla moving behind us and coming closer to see what we were about. She had a good look from a few yards away and then moved on to join the rest of the group as they climbed into the tops of the trees.

I shall never forget the sight of Neptune climbing the tree with consummate ease—and even striking the pose of the long-dead George. But the large tooth display was the result of a languid yawn as he paused before climbing even higher.

There is no greater privilege in the world than seeing a group of lowland gorillas in the wild in the Congo—sixty-eight years after seeing that unfortunate but great ambassador for gorillas, Alfred.