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One [[mirror test]] in Gabon shows that western gorilla silverbacks react aggressively when faced with a mirror.<ref>Hubert-Brierre, Xavier (2015) [https://www.youtube.com/watch?v=tz0avWZoqjg Silverback always shows aggressiveness towards mirrors - Le dos argenté agresse toujours son reflet]. YouTube</ref>
==Conservation status==
The [[World Conservation Union]] lists the western gorilla as [[critically endangered]], the most severe denomination next to global extinction, on its 2007 [[IUCN Red List|Red List of Threatened Species]]. The [[Ebola virus]] might be depleting western gorilla populations to a point where their recovery might become impossible, and the virus reduced populations in protected areas by 33% from 1992 to 2007, which may be equal to a decline of 45% for a period of just 20 years spanning 1992 to 2011.<ref name=iucn/><ref name="cbs news"/> [[Poaching]], commercial logging and [[civil war]]s in the countries that compose the western gorillas' [[habitat]] are also threats.<ref name="cbs news"/> Furthermore, reproductive rates are very low, with a maximum intrinsic rate of increase of about 3% and the high levels of decline from hunting and disease-induced mortality have caused declines in population of more than 60% over the last 20 to 25 years. Rather, under the optimistic estimate scenarios, population recovery would require almost 75 years. Yet within the next thirty years, habitat loss and degradation from agriculture, timber extraction, mining and climate change will become increasingly larger threats. Thus, a population reduction of more than 80% over three generations (i.e., 66 years from 1980 to 2046) seems likely.{{Citation needed|date=June 2012}}
[[File:Gorilla Male perspective 5.jpg|thumb|right|upright 1.0|A skull of a male]]
In the 1980s, a census taken of the gorilla populations in equatorial [[Africa]] was thought to be 100,000. Researchers adjusted the figure in 2008 after years of poaching and deforestation had reduced the population to approximately 50,000.<ref name = "cnn_found" />
Surveys conducted by the [[Wildlife Conservation Society]] in 2006 and 2007 found around 125,000 previously unreported gorillas have been living in the swamp forests of [[Lake Tele]] Community Reserve and in neighbouring Marantaceae (dryland) forests in the [[Republic of the Congo]]. This discovery could more than double the known population of the animals, though the effect that the discovery will have on the gorillas' conservation status is currently unknown.<ref name = "cnn_found" /><ref>{{cite web|url=http://www.cbsnews.com/stories/2008/08/05/tech/main4321037.shtml |title=Thousands Of Rare Gorillas Found In Congo |publisher=Cbsnews.com |date=5 August 2008 |access-date=3 July 2009}}</ref>
With the new discovery, the current population of western lowland gorillas could be around 150,000–200,000. However, the gorilla remains vulnerable to [[Ebola]], [[deforestation]], and [[poaching]].<ref name = "cnn_found">{{cite news | title = More than 100,000 rare gorillas found in Floral Park | publisher = CNN | date = 5 August 2008 | url = http://www.cnn.com/2008/WORLD/africa/08/05/congo.gorillas/index.html | access-date = 5 August 2008}}</ref>
Estimates on the number of Cross River gorillas remaining is 250–300 in the wild, concentrated in approximately 9-11 locations.<ref name=iucn_diehli>{{cite iucn|author=Oates, J. F.|author2=Bergl, R. A.|author3=Sunderland-Groves, J.|author4=Dunn, A.|name-list-style=amp|year=2008|url=https://www.iucnredlist.org/details/39998/0|title=''Gorilla gorilla ''ssp.'' diehli''|access-date=26 April 2012|ref=harv}}</ref> Recent genetic research<ref>{{Cite journal| pmid = 17257109| year = 2007| author1 = Bergl| first1 = R. A.| title = Genetic analysis reveals population structure and recent migration within the highly fragmented range of the Cross River gorilla (''Gorilla gorilla diehli'')| journal = Molecular Ecology| volume = 16| issue = 3| pages = 501–16| last2 = Vigilant| first2 = L|url=https://www.researchgate.net/publication/6547369_Genetic_analysis_reveals_population_structure_and_recent_migration_within_the_highly_fragmented_range_of_the_Cross_River_gorilla_%28Gorilla_gorilla_diehli%29| doi = 10.1111/j.1365-294X.2006.03159.x}}</ref> and field surveys suggest that there is occasional migration of individual gorillas between locations. The nearest population of western lowland gorilla is some 250 km away. Both loss of habitat and intense hunting for [[bushmeat]] have contributed to the decline of this subspecies. In 2007, a conservation plan for the Cross River gorilla was published, outlining the most important actions necessary to preserve this subspecies.<ref>Oates, J., Sunderland-Groves, J., Bergl, R., Dunn, A., Nicholas, A., Takang, E., Omeni, F., Imong, I., Fotso, R., Nkembi, L. and Williamson, E.A. (2007). [http://www.primate-sg.org/PDF/CRG.Action.Plan.pdf Regional Action Plan for the Conservation of the Cross River Gorilla (''Gorilla gorilla diehli'')]. IUCN/SSC Primate Specialist Group and Conservation International, Arlington, VA, U.S.</ref> The government of Cameroon has created the Takamanda National Park on the border with Nigeria, as an attempt to protect these gorillas.<ref>Black, Richard (28 November 2008) [http://news.bbc.co.uk/1/hi/sci/tech/7754544.stm Protection boost for rare gorilla]. BBC News</ref> The park now forms part of an important trans-boundary protected area with Nigeria's Cross River National Park, safeguarding an estimated 115 gorillas—a third of the Cross River gorilla population—along with other rare species.<ref>[http://newswise.com/articles/view/546911/ New National Park Protects World's Rarest Gorilla]. Newswise. 26 November 2008</ref> The hope is that these gorillas will be able to move between the Takamanda reserve in Cameroon over the border to Nigeria's Cross River National Park.
==See also==
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