Chimpanzee

Our closest cousin, the chimpanzee (Pan troglodytes) is currently classed as endangered under the IUCN with it estimated to consist of a population of between 172,700 to 299,700 chimpanzees remaining. Chimpanzees have already gone domestically extinct in 4 countries already and are put under serious pressure in all other countries they reside in. 

This population has displayed an exponential decline with a report coming from the American Journal of Primatology (2017) which had predicted there to be an 80.2% decline within the last 25 years. More recent studies have said that great apes are in less danger than previously thought. Although, chimpanzees are in a better position, they are still seriously vulnerable and this will provide us with greater opportunity to prevent the extinction of this species. The largest  survey of great apes had inferred there to have been a fifth decrease in chimpanzees between 2005-2013.

Great apes are seriously vulnerable to decrease in population as they are classed as a type I in the survivorship curve which means they have very few natural predators and so will have a slow reproductive rate and prolonged maternal care. These species are highly vulnerable to this decline as they aren't capable of replenishing their population. 

This reduced population of chimpanzees are a by-product of habitat loss, degradation, commercialization of bushmeat and being infected by various fatal diseases such as ebola. Logging is a serious factor for this decline.

Morgan and Sanz (2007) had stated logging causes the loss of their food source, habitat and creates disruptions. This is especially evident in clear cutting logging. 

Studies on selective logging has been undertaken on the effects it creates on the great apes. It was discovered that most gorillas displayed positive responses to selective logging, however, the chimpanzee were significant more vulnerable. Positive effects are a result from increased light that can reach the forest floor and there is a strong correlation between the amount of sunlight the forest floor receives and the abundance/ diversity of the floral composition providing a greater food source prior to the logging. Although, chimpanzees more commonly responded negatively to all logging events there was rare occasions they displayed positive responses.

It is hypothesized that this decline response is because of the chimpanzee's territorial behaviour to one another. When logging begins, the chimpanzees will feel unsafe in their territory they will migrate which is likely to force them to enter a different clan's  territory. This will then lead to brutal fighting between the chimpanzee's clans.

References
Gaworecki, M., 2017. Western Chimpanzee Numbers Declined By More Than 80 Percent Over The Past Quarter Century. [online] Mongabay Environmental News. Available at: <https://news.mongabay.com/2017/07/western-chimpanzee-numbers-declined-by-more-than-80-percent-over-the-past-quarter-century/> [Accessed 22 July 2020].

  World Wildlife Fund. 2020. Chimpanzees | Species | WWF. [online] Available at: <https://www.worldwildlife.org/species/chimpanzee> [Accessed 22 July 2020].

World Wildlife Fund. 2020. Largest Ever Study Of Gorillas And Chimpanzees Finds More Than Expected | Stories | WWF. [online] Available at: <https://www.worldwildlife.org/stories/largest-ever-study-of-gorillas-and-chimpanzees-finds-more-than-expected> [Accessed 22 July 2020].