Gorillas eat nuts, unexpectedly


This 2010 video says about itself:

Gorilla mums

Two first-time mothers care for their babies in Limbe, Cameroon. Both were orphaned as infants when their parents were killed for bushmeat, then sold into the animal trade; fortunately they were then rescued and cared for by the dedicated staff of the Limbe Wildlife Centre. The first mum is called Brighter and her baby is Balinga (male); the second is Akiba with her female baby Atinbi.

From the Max Planck Institute for Evolutionary Anthropology in Germany:

Unexpected nut eating by gorillas

August 2, 2019

Scientists have observed a population of western lowland gorillas in Loango National Park, Gabon using their teeth to crack open the woody shells of Coula edulis nuts. The researchers combined direct feeding observations and mechanical tests of seed casings to show that gorillas may be taxing their teeth to their upper limits, year after year, to access this energy rich food source.

Despite their large body size, gorillas are known to have a vegetarian diet consisting almost exclusively of leafy vegetation and fruit. Their teeth are large and high crested when compared to other great apes which is traditionally seen as an adaptation to them spending a large amount of time chewing tough fibrous plant material. In contrast, their teeth are not well adapted to eating hard objects, such as nuts encased in a woody shell, because the high crests on their molar teeth would be at risk of damage. “I was amazed when we first observed the nut eating by the gorillas,” states Martha Robbins, senior author on the paper. “We can not only see it, but also hear it, as the shell gives way to the incredible strength of their bite. Gorillas obviously have large, powerful jaws, but we did not expect to see this because their teeth are not well-suited to such behavior.”

The nuts of Coula edulis are encased in a hard, woody shell that takes around 271 kg of force to crack. Yet for the three months the nuts are available, the gorillas of Loango National Park concentrate their feeding on the energy rich kernels, spending up to three hours a day chomping through nuts. This is surprising as animals that eat very hard food items tend to have strong, rounded molars that act like a pestle and mortar and are very efficient at cracking brittle foods. Like other foliage eaters, gorilla teeth have higher crests providing extra cutting edges for slicing tough material. Under the monumental bite force required to crack nuts, teeth with sharp edges are prone to break meaning they may be worn away quickly. The researchers were surprised to learn that the gorillas at Loango are regularly gambling with their teeth and taxing them close to their predicted mechanical limits. While some primates, like chimps, protect their teeth by using tools to crack open nuts, it appears that the gorillas at Loango National Park rely on brute strength to break through the woody shells of Coula edulis nuts. The fact they do this year after year indicates that gorilla teeth may be stronger than previously thought.

The research also implies that western lowland gorillas have much greater dietary breadth than previously believed. The absence of nut cracking behavior in other populations of western gorillas where the nuts are also present suggests the behavior may be cultural, if gorillas need to observe and learn the behavior from other group members. “The fact that this nut eating is observed in Loango but not in other forests in central Africa where the nut occurs stresses the importance of studying and conserving gorillas throughout the habitat where they are found,” says Robbins.

Discovering that some gorillas routinely partake in nut cracking with their teeth could also influence the way researchers interpret the fossil remains of human ancestors. Despite having teeth seemingly shaped for a leafy diet the study shows that western lowland gorillas are capable of routinely cracking nuts, which has important implications for the ways researchers predict the diet of human ancestors based on the shape of their teeth.

How gorillas mourn their dead


This 8 January 2018 video says about itself:

Gorilla Brothers Mourn Their Dead Father | Wild Things

After losing their father, two mountain gorillas display their grief and mourning in a very human way. From Mountain Gorilla: A Shattered Kingdom.

From PeerJ:

Gorillas gather around and groom their dead

April 3, 2019

It is now known that many animals exhibit unique behaviors around same-species corpses, ranging from removal of the bodies and burial among social insects to quiet attendance and caregiving among elephants and primates. Researchers in Rwanda and Democratic Republic of Congo have been able to take a close look at the behavioral responses to the deaths of three individuals — both known and unknown — in gorillas and have reported their findings in PeerJ — the Journal of Life and Environmental Sciences.

Scientists from the Dian Fossey Gorilla Fund, the University of California Davis, Uppsala University, and the Congolese Institute for the Conservation of Nature observed and filmed the behavior of mountain gorillas around the corpses of a 35-year-old dominant adult male and a 38-year-old dominant adult female from the same social group living in Volcanoes National Park, Rwanda. Both individuals had died a few hours earlier of illnesses possibly linked to their advanced age. Researchers also studied the behavior of a group of Grauer’s gorillas who found the body of a recently deceased adult male in Kahuzi-Biega National Park, Democratic Republic of Congo.

Researchers predicted that more individuals would engage with the corpses of familiar members of their own group compared to the extra-group mature male and that individuals who shared close social relationships with the deceased would be the ones to spend the most time close to body.

To the researcher’s surprise, the behavioral responses toward the corpses in all three cases were remarkably similar. In all three cases, animals typically sat close to the body and stared at it but they also sniffed, poked, groomed and licked it.

In the two mountain gorilla cases, individuals that shared close social relationships with the deceased were the ones who spent the most time in contact with the corpse. For example, a juvenile male who had established a close relationship with Titus, the dominant mountain gorilla silverback male, after his mother left the group, remained close and often in contact with the body for two days, and slept in the same nest with it. The juvenile son of Tuck, the deceased adult female, groomed the corpse and even tried suckling from it despite having already been weaned, a behavior that could indicate his distress near his mother’s body.

This work is not only of interest regarding how animals perceive and process death, but it also has important conservation implications. Close inspection of corpses can present a serious risk for disease transmission. Contacts between healthy individuals and infected corpses may be a major way through which diseases like Ebola, which have affected and killed thousands of gorillas in Central Africa, spread among gorillas.

Gorillas’ social life, new research


This December 2015 video says about itself:

A group of western lowland gorilla living in Loango national park, Gabon. Research is being carried out on these apes by the Max Planck Institute.

From the University of Barcelona:

Social behavior of western lowland gorillas

February 6, 2019

A new study published in the journal Proceedings of the Royal Society B: Biological Sciences reveals one of the enigmas related to the social behaviour of the western lowland gorilla (Gorilla gorilla gorilla) in the heart of the African equatorial rainforest. These primates show a dynamic social structure -individuals change frequently between families- with a high degree of tolerance and peaceful coexistence among the members, according to the new article which counts on the participation of the experts José Domingo Rodríguez Teijeiro, Magdalena Bermejo, Guillem Molina-Vacas, from the Faculty of Biology and the Biodiversity Research Institute of the University of Barcelona (IRBio).

According to the authors, this social behaviour may have played an important role in the evolutionary story of the species, easing the exchange of information and a better exploitation of trophic resources. However, this social dynamics may have worsened the impact of some infectious diseases in the population of gorillas, experts warn. In this context, epidemic Ebola virus outbreaks, which affected the primate population in Congo between 2002 and 2004, caused the disappearance of 95 % of this ape, causing this species to be in critical danger of extinction according to the Red List of threatened species by the International Union for the Conservation of Nature (IUCN).

In the new study, carried out in the Ngaga Forest in the Republic of the Congo, counts on the participation of German Illera (Great Apes Conservation/Research Odzala-Lossi and SPAC gGmbH, Republic of the Congo), Giovanni Forcina, Rubén Bernardo-Madrid, Eloy Revilla and Carles Vilà (Doñana Biological Station EBD-CSIC) and other experts of the University of Rennes (France).

After the western lowland gorillas in the heart of the forest

The ecology and behaviour of the western lowland gorilla inside the equatorial forests was an enigma so far. Since the first scientific studies started, differences between the behaviour of these two African primates were known: the western lowland gorilla (Gorilla gorilla gorilla) -living in rainforests around the basin of the River Congo- and the mountain gorilla (Gorilla gorilla beringei), a better studied primate in the volcanic mountainsides of the African Rift. At the moment, hunting and epidemics endanger the survival of wild populations of these primates which share more than 98% of genetic material with the human species.

Unlike the mountain gorilla, which has aggressive and infrequent interactions between families, the western lowland gorilla was known to have frequent and peaceful interaction between members of the families. However, due a low visibility inside the forests, western lowland gorillas had been studied in bais, typical open clearings which are the meeting point for families of the species to feed from plants rich in mineral salts.

As part of the study, the experts conducted a scientific monitoring over five years to three families of the western lowland gorilla in the same heart of the Congo forest. According to the conclusions, interaction between individuals from different families is common and peaceful so the individuals eat and play together with no signs of aggression.

Regarding methodology, experts profiled an image of the social structure and parentage relations of more than 120 gorillas through the genetic analysis of faeces samples taken over four months -in families and single individuals- in the Ngaga forest.

A dynamic social structure with no records of infanticides

Data show families have a dynamic social structure in which individuals conduct frequent changes among family groups. Young individuals are usually outside the family and enter temporarily other family groups in which they have no close relatives. This social behaviour could be linked to the lack of infanticide records in this species, experts note.

This new study shows the image of a modular society featured by the existence of strong ties which do not avoid the transfer of individuals between different families and a high degree of tolerance between their members. The results of this study show the importance of complementing in situ monitoring studies with non-invasive genetic analysis to find the structure and social dynamics in animal species which are hard to have access to. At the same time, conclusions highlight the importance of social behaviour in disease transmission and the development of effective conservation strategies in the long run.

Rwandan mountain gorillas’ food, new study


This 2017 video says about itself:

Mountain Gorilla: A Shattered Kingdom [Full Documentary] | Wild Things

A unique study of family life in the world of nature’s gentle giants – and of the impact of man’s turbulent politics on that peaceful world. This extraordinary portrait of a group of wild gorillas is a family saga rich in the grand themes of any human drama – death, adolescent rebellion, jealousy and parenthood.

From ScienceDaily:

Foraging of mountain gorillas for sodium-rich foods

September 19, 2018

A new Biotropica study examines mountain gorillas in Rwanda and their foraging for sodium-rich food in both national park areas and lands managed by local communities.

Obtaining sodium likely creates an incentive for the gorillas to leave park areas and make forays into high-altitude habitat. Both locations are not without risks: exiting their natural habitat and feeding on crops may increase human-wildlife conflict and visiting high-altitude areas may increase the risk of hypothermia.

The results may advance the discussion of how to adapt local human land use to effectively curb human-wildlife conflict.

“When gorillas raid eucalyptus stands outside the national park, they come in contact with local inhabitants, which puts both ape and human at risk. To discourage the gorillas from crossing into farmlands near the forest, agricultural practices may need to be reconsidered”, said lead author Dr. Cyril Grueter, of The University of Western Australia, in Perth. “Ideally one would want to favor plant species that are nutritionally unattractive to the gorillas.”

MOUNTAIN GORILLAS GET MUCH-NEEDED BOOST The world’s longest-running gorilla study was started in 1967 by famed American primatologist Dian Fossey. Fossey, alarmed by poaching and deforestation, predicted the species could be extinct by 2000. But a sustained conservation campaign has averted the worst. [AP]

Good African mountain gorilla news


This video says about itself:

5 November 2014

Mountain Gorilla – Full Documentary HD

The mountain gorilla (Gorilla beringei beringei) is one of the two subspecies of the eastern gorilla. There are two populations. One is found in the Virunga volcanic mountains of Central Africa, within three National Parks: Mgahinga, in south-west Uganda; Volcanoes, in north-west Rwanda; and Virunga in the eastern Democratic Republic of Congo (DRC).

The other is found in Uganda’s Bwindi Impenetrable National Park. Some primatologists consider the Bwindi population in Uganda may be a separate subspecies, though no description has been finished. As of November 2012, the estimated total number of mountain gorillas is around 880.

From the Max Planck Institute for Evolutionary Anthropology in Germany:

Number of wild mountain gorillas exceeds 1,000

The population of mountain gorillas in the Virunga Volcanoes has more than doubled in the past three decades

May 31, 2018

Summary: A recent census of the critically endangered mountain gorillas conducted in the Virunga Volcanoes found a minimum of 604 individuals. In combination with the 400 individuals living in the only other population in Bwindi Impenetrable National Park, Uganda, these new results push the total number of wild mountain gorillas in the world to over 1000.

“This represents one of the rare success stories in conservation. The population of mountain gorillas in the Virunga Volcanoes has more than doubled in the past three decades, despite intensive threats of poaching, habitat degradation, and civil conflict”, stated Martha Robbins, research scientist and gorilla expert at the Max Planck Institute for Evolutionary Anthropology. “This increase exemplifies the dedicated efforts of the governments of Rwanda, Uganda, and the Democratic Republic of Congo to conserve these critically endangered great apes, and notably, the hard work of park staff on the ground. This dramatic increase also shows that extreme conservation efforts including tourism, veterinary work, and community projects can have a positive impact on one of our closest living relatives.”

The census was a combination of intensive fieldwork in 2015 and 2016 and detailed genetic analysis. Field teams walked more than 2,000 kilometres to sweep intensively through the entire 440 square kilometres Virunga Volcanoes searching for trails and nest sites left by the gorillas. Genetic analysis, taking more than 18 months to complete, was conducted on approximately 1,100 fecal samples to determine that there are a minimum of 186 unhabituated (not regularly contacted by humans) gorillas. The remaining 70 percent of the population consists of 418 gorillas that are habituated for research and tourism.

The last census conducted in the Virunga Volcanoes was in 2010, when the population was estimated to be a minimum of 480 gorillas. The current figure represents a 26 percent increase in the number of gorillas over a six-year-period, which is a 3.8 percent annual rate of increase. This increase is due to improved methods used in this recent census as well as actual growth of the population. The 604 gorillas were found in 41 social groups and 14 solitary males.

Conducting the census was a large collaborative effort among the park services of the three countries where mountain gorillas live, namely Rwanda, Uganda, and the Democratic Republic of Congo, several non-governmental conservation organizations, and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Routine censusing such as this one is a crucial part of adaptive management strategies to help determine whether a population is increasing or decreasing in size and decide if conservation efforts are effective or should be modified. The population of mountain gorillas in the Virunga Volcanoes numbered only about 250 gorillas in the mid-1980’s.

“Genetic analysis of DNA from fecal samples allows us to count gorillas without even observing them,” observes Linda Vigilant, head of the primatology genetics lab in Leipzig. “Next we will be analyzing the detection history of individuals over time to get more insights into how groups form and group membership changes.”

Mountain gorillas in Rwanda


This video says about itself:

25 September 2017

Follow along as National Geographic photographer Ronan Donovan hikes through Volcanoes National Park in northwestern Rwanda in search of Dian Fossey’s famed [mountain] gorillas.

Fuel efficient stoves reduce tree cutting in Rwanda forest: here.

Dian Fossey on gorillas, video


This video says about itself:

Dian Fossey Narrates Her Life With Gorillas in This Vintage Footage | National Geographic

11 September 2017

The 1973 National Geographic film The Mountain Gorilla documented zoologist Dian Fossey’s study of and interaction with the great apes of Central Africa from 1967 to 1972.