Gorilla gorilla (amended version of 2016 assessment)
Maisels F, Strindberg S, Breuer T, Greer D, Jeffery KJ & Stokes E (2018) Gorilla gorilla (amended version of 2016 assessment). The IUCN Red List of Threatened Species [IUCN website] 2018. https://doi.org/10.2305/IUCN.UK.2018-2.RLTS.T9404A136250858.en
Assessment Information: Justification: Western Lowland Gorillas have a large geographic range, covering almost 700,000 km². Between 1983 and 2000, the country of Gabon lost half its Gorilla population (Walsh et al. 2003). A recent evaluation estimated population declines using a predictive model that incorporated survey data collected across the range of the taxon between 2003 and 2013. The results show an 18.75% decline between 2005 and 2013, corresponding to an annual loss of ~2.56% (Strindberg et al. in prep). These population decreases were driven by a combination of poaching and disease. The current size of the population is being evaluated, but thought to be in the order of a few hundred thousand.Despite their abundance and wide geographic range, in 2008 Western Lowland Gorillas were listed as Critically Endangered under criterion A: a population reduction of more than 80% over three generations (one generation is ~22 years). This listing was based on population losses due to poaching, disease and habitat loss. Illegal hunting has not ceased despite intense anti-poaching efforts and the threat of Ebolavirushas not been removed: poaching is intensifying with the expansion of access routes into forests and Zaire ebolavirusis still present in the forests of the region. In addition, habitat loss due to industrial agriculture is increasing, and the effects of climate change will become more evident. At a conservative rate of reduction (2.56% per year rather than 4%, calculated from Walsh et al. 2003), the reduction in the Western Lowland Gorilla population is predicted to exceed 80% over three generations (i.e., 66 years, 2005-2071).Gorilla gorilla gorilla thus qualifies as Critically Endangered.
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Ms Kathryn Jeffery
Research Fellow, Biological and Environmental Sciences
Dr Fiona Maisels
Honorary Professor, Biological and Environmental Sciences