Today is #WorldGorillaDay!
Today is the day to celebrate all things gorilla. Sharing 98% DNA with us, the gorilla is a charismatic, caring and extraordinary great ape. The gorilla consists of 2 species, the western and eastern gorilla. These two species each has 2 subspecies, the Western Lowland Gorilla (Gorilla gorilla gorilla), the Grauer’s Gorilla (G. beringei graueri), the Mountain Gorilla (G. beringei beringei) and the Cross River Gorilla (G. gorilla diehli). World Gorilla Day however, isn't just for celebrating the gorilla, it’s also a day to spread awareness about their threats and conservation, to bring recognition to those on the front line of their conservation and to encourage people to take action.
To celebrate World Gorilla Day, we explored gorilla research published between 2018 and 2021. To showcase recent research, we chose 4 different papers, each focused on one gorilla subspecies. We hope to give you just a small insight into the science among gorillas and bring awareness to the importance of science in the conservation of these great apes.
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It turns out the western lowland gorilla is rather neighborly compared to other species of gorilla. A study published in 2019, ‘From Groups to Communities in Western Lowland Gorillas’ by Forcina, et al (2019), studied the encounter between three groups of western lowland gorillas and discovered a highly dynamic social system. The social structure and dynamics of the western lowland gorilla is poorly understood compared to the better-studied mountain gorilla (Gorilla beringei beringei).
The western lowland gorilla lives in smaller, more intimate groups compared to other species, with an average of 5 gorillas per group. This group is composed of a silverback, a couple of black backed males, several adult females and their infant and juvenile offspring. Forcina and Co. studied western lowland gorillas over a period of five years in Ngaga Forest, on the southwestern boundary of Odzala-Kokoua National Park, Democratic Republic of Congo. The home ranges of each group overlapped which made these gorillas the perfect candidates to study inter-group encounters.
The team found a significant difference in the western lowland gorilla behaviour towards their neighbors compared to other gorilla species. Interactions between neighboring groups were generally non-aggressive. When crossing paths with another group, youngsters would socially play with one another and adults would tolerate the presence of the other. It was also recorded that groups would ‘exchange members’, concluding that this may be likely to be due to the relations between the two groups, with some members being related.
The meeting between two gorilla groups can sometimes be met by aggression from the dominant silverback, the leader and most mature male in the group. However, interestingly for western lowland gorillas, this isn't the case. Unlike their cousins, the mountain gorilla, western lowland gorillas do not display a behaviour called infanticide, which involves the killing of young offspring by a mature adult. The absence of this behaviour from mature males highlights the docility of the western lowland gorillas social system and the tolerance the adults endure for the intimate experience they gain from interacting with another group of gorillas.
But why are these interactions so important for this species? Understanding the western lowland gorillas social interactions also gives us insight into the sharing of behavioural and cultural traits. This reflects on an ever-changing society within western lowland gorilla. Adult tolerance paired with highly social immature gorillas can be reflective of our societies today. Researchers also believe this social practice may also increase the western lowland gorillas sensitivity to infectious diseases.
Read the full paper here: https://royalsocietypublishing.org/doi/full/10.1098/rspb.2018.2019
Cross River “Gorilla Guardians”
The Cross River gorilla (Gorilla gorilla diehli) is the most threatened of all species of gorilla. Only 250-300 individuals survive today. This species population has severely suffered as it continues to decline due to habitat loss, fragmentation and hunting, particularly those groups roaming outside of protected areas. The Cross River gorilla's home overlaps with that of human settlements. Three villages within the Cross River National Park in Nigeria and another three villages within the Takamanda National Park in Cameroon, are both putting pressure on the existing individuals that roam those regions.
The past two decades have seen key actions being implemented, in hope that the Cross River gorilla can be saved from the brink of extinction. Some of these initiatives included the creation and management of protected areas, connectivity plans, research and conservation education. Despite many areas such as the Takamanda National Park and Kagwe Gorilla Sanctuary safely under protection, there is still a significant number of gorillas that live outside of these protected areas. Within the unprotected areas, hunting for bushmeat is prevalent, as well as extraction of non-timber products, timber and medicine.
Sadly, due to the large number of existing protected areas, the government of Cameroon is unlikely to review more Cross River gorilla habitats for protection due to the amount of protected areas already in the region. Therefore, a different conservation strategy needed to be established.
A study published in 2019 by Akeji, et al (2019), provided an update on a community-based program called “Gorilla Guardians”. This program was designed to involve the local communities in monitoring and conserving Cross River Gorillas. Having been established since 2009, the program's success has now allowed for 12 communities to be involved in this program. The Gorilla Guardians role is primarily to communicate with their communities, conservation organisations and government officials. They were formally trained on monitoring techniques needed to identify gorilla signs such as feeding trails and nests, taught the use of equipment such as GPS units and were trained in Cameroon Wildlife laws and related legislation. These tools allow the Gorilla Guardians to be just that, guardians to the Cross River gorillas.
The Gorilla Guardians cannot, and do not work alone. Bringing teamwork to the forefront, the Gorilla Guardians rely on forest users, usually hunters and those who use the forest for non-timber forest products, to report on sighting of ape nests and other information on the gorilla populations, such as approximate location, species and freshness of sites. The importance of forest users has allowed for detailed, updated information on the distribution of the gorillas on an annual basis.
Gorilla guardians in these regions continue to build their knowledge and have consistent support from external organisations such as field staff of the Wildlife Conservation Society (WCS). On a three monthly basis, the Guardians, a forest user and the WCS field staff undergo a guided survey led by the forest user to examine and verify reported nest sites. The program is strengthened by the Village Forest Management Committees. This crucial body helps to facilitate consultation, negotiation, education, and participation, and is primarily made up of the younger generation, women, elites, farmers, forest users, and the chief.
Having been a success up to this point, the Gorilla Guardians and those working alongside them, continue vigorously to save their gorillas. This community-based monitoring approach proves to be effective in monitoring the highly threatened population of the Cross River gorilla.
Food of the lowlands
Little is known of the Grauer’s gorilla (G. beringei graueri) ecology and life history. This critically endangered gorilla can be found only in the eastern Democratic Republic of Congo where a large amount of research has been centred upon groups living in montane habitats in high elevation, which represents only a small portion of the overall Grauer’s gorillas population. The gorillas' lowland evergreen environments have been sparsely studied, with only one other key study representing the species lowland population. A recent study, however, set out to change this.
Van der Hoek, et al (2020) published an introductory paper (2020) on the Grauer’s gorillas diet in low-elevated forests located in the Nkuba Conservation Area (NCA) covering parts of Maiko National Park and Kahuzi-Biega National Park in the Democratic Republic of Congo. The difference in diet varies substantially across gorilla groups, populations, subspecies, and species. To grasp an idea of how the Grauer’s gorillas diet in low elevated environments alters from that of the populations in high elevated environments, the research team tracked 1-3 gorilla groups within their study sites and analysed feeding signs found along the trail of the tracked gorillas.
The Grauer’s gorillas living within the NCA were found to feed on both vegetative plants and fruits year round. The team highlights the seasonal fluctuation in what the gorillas ate, with an increase in fruit during the wet season, behaviour that is seen in other species of gorilla that occupy lower elevation. To compare, it has previously been shown that gorillas living in higher elevations such as montane habitats generally do not have access to fruit due to availability. The mountain gorilla (Gorilla beringei beringei) within montane habitats in Virunga, for example, eat high amounts of fibrous foods such as herbaceous vegetation, leaves, pith and bark, which reflects fruit being partly unavailable in higher elevated regions. In contrast, mountain gorillas studied in lower elevated regions such as Bwindi Impenetrable National Park, have a much higher percentage of fruit in their diet. Much like the mountain gorillas, this theory can be transferable to that of the Grauer’s gorillas in the NCA as seen in Van der Hoek, et al (2020) study.
The little amount of information we have for the Grauer’s gorillas living in the lower elevated areas is concerning. As Grauer’s gorilla population continues to decline, this research paper builds a baseline dataset that can be used to understand human-induced changes in the forest ecosystem, and how these changes may be affecting the food available to the gorillas. Additionally, this paper is important as a starting point for the development of reforestation targets and conservation and management strategies.
Read the full paper here: https://www.karger.com/Article/Abstract/515377
Wildlife Tourism and the Mountain Gorilla
Wildlife tourism plays a major lifeline for many countries. In 2018 the wildlife tourism industry generated an astonishing US$120.1 billion to the global GDP. The more threatened and rare the animal the more desire people have to see them in the wild. However, this demand to see some of the world's rarest animals in their natural habitat may pose a threat to their wellbeing, especially those closest related to us, like gorillas. A good example of the wildlife tourism industry is mountain gorilla (Gorilla beringei beringei) trekking. Gorilla trekking draws in huge revenue for countries like Uganda, Rwanda and Democratic republic of congo (DRC), as tourists flock to experience a guided hike through dense foliage in an attempt to encounter a family of wild mountain gorillas. Tourist revenue plays a significant role in the livelihoods of the local communities involved and can contribute to the conservation of the habitats and gorillas.
Among other threats including poaching, political instability and habitat degradation, the mountain gorilla also faces the threat of human-to-gorilla disease transmission. Disease transmission is only a threat if, and when gorillas come in contact with humans. With a growth in wildlife tourism this threat is becoming increasingly prevalent. Gorillas are especially at risk of disease transmission from humans due to their close genetic similarity with us.
In an attempt to understand the scope of the risk and to discover potential ways to reduce infectious disease transmission by humans, a team of scientists in 2018 provided questionnaires to a number of tourists visiting Bwindi Impenetrable National Park, Uganda. Researchers hoped to document self-reported health status, explore risk of disease transmission to gorillas and to assess tourists' reported willingness to wear disposable face masks during trekking periods.
Their research highlighted just how much threat tourists pose. Contact made and how close the tourists were to gorillas while trekking had shown an increase compared to previous studies having been within 5 m or less of the gorilla family. A number of studies and publications strongly recommended maintaining a distance of 7 m between tourists and gorillas as a way to minimise risk of disease transmission. More striking, participants in this study claimed that on more than one occasion visitors and gorillas came in direct contact with one another. The 7 m recommendation is strongly encouraged as a way to avoid contact with gorillas. Like all animals, gorillas behaviour is unpredictable, particularly curious youngsters. However, a 7 m distance allows the guides and tourists time to move away slowly if a gorilla group member decides to venture towards the tourists.
This 2018 study also highlighted that 25% of tourists would trek if sick, tourists also practiced poor vaccination recall. Ultimately, precaution must be kept when practicing wildlife tourism. As the world slowly gets back to normal after the Covid-19 global pandemic, the screening of contagious and deadly diseases must be thorough now more than ever. The limited genetic pool of the mountain gorilla puts this species at higher risk and may impact gorilla immune systems, making them even more vulnerable to diseases.
Read the full paper here: https://besjournals.onlinelibrary.wiley.com/doi/full/10.1002/pan3.10187