IUCN / SSC Cat Specialist Group - Digital Cat Library
   

 

View printer friendly
Henschel, P.; Bauer, H.; Sogbohoussou, E.; Nowell, K.
_Panthera leo_ (West Africa subpopulation), lion
2015  Full Book

This is a subpopulation assessment of the Lion population in West Africa, which has been classified as a separate subpopulation since 2004 (Bauer and Nowell 2004), as it was considered to be isolated from Lion populations of Central Africa, with little or no exchange of breeding individuals (Chardonnet 2002, Bauer and van der Merwe 2004). The prior assessment of the West African subpopulation used political boundaries to delineate its extent, incorporating populations from Senegal in the West to Nigeria in the East. Recent molecular analyses established that Lions in a relict population in central Nigeria (in Yankari Game Reserve) are closely related to Lions in Cameroon (Central Africa), while Lions from a population in western Nigeria (in Kainji Lake National Park (NP)), situated west of the lower Niger River, genetically cluster with Lions from Benin and Senegal, and are genetically distinct from Lions in Central Africa (Bertola et al. unpublished). These findings suggests that the lower Niger River acts as a barrier to Lion dispersal, separating Lions in West Africa (west of the lower Niger River), from Lions in central/eastern Nigeria and those of Central Africa. The current assessment therefore defines all populations west of the lower Niger River as belonging to the isolated West African subpopulation, which is justifiable in terms of Lion biology. However, IUCN and other international organizations conventionally use national boundaries for regional delineation (although not for subpopulation-level Red List assessments), and we will show that the assessment would have the same result if national boundaries had been used. Recent (2006-2013) survey work covering 17 protected areas suspected to harbour Lions by participants of the IUCN SSC regional conservation planning workshop for Lions in West and Central Africa, held in 2005 (IUCN 2006), confirmed continued Lion presence in only three of those protected areas: Niokolo- Koba NP in Senegal (16 [0-54] Lions), the tri-national W-Arly-Pendjari Complex in Benin, Burkina Faso and Niger (356 [246-466] Lions) and Kainji Lake NP in Nigeria (32 [23-63] Lions) (Henschel et al. 2014). Lions were no longer recorded in Guinea-Bissau, Mali, C“te d'Ivoire and Togo. Rumours about the species' presence persist in Guinea's Haut Niger and Kankan Reserves (Henschel et al. 2014), as well as for Mole NP in Ghana (originally reported as a short communication in African Zoology, but subsequently refuted in a Letter to the Editors; the debate which ensued resulted in the Editors-in-Chief of the journal retracting all the publications concerned with a request not to cite them). The recent survey results suggest that only 404 (269-583) Lions remain in West Africa (Henschel et al. 2014). Population size estimates relied on track counts (cf. Funston et al. 2010) in all areas apart from Kainji Lake NP, and included large cubs and sub-adults. Considering that 40-60% (average: 50%) of a Lion population typically consists of immature individuals (Schaller 1972, Stander 1991, Vanherle 2011), we calculated the number of mature individuals by halving population size estimates for sites where track counts were used; we established confidence intervals by using the higher end of the proportional range of immature individuals with the minimum population size estimate to calculate the lower limit, and by using the lower end of the proportional range of immature individuals with the maximum population size estimate to calculate the upper confidence limit. This results in an estimated 218 (121-375) mature animals remaining in the West African subpopulation. Most of these Lions (ca 90%) persist in a single population in W-Arly-Pendjari. The recent surveys represented the first comprehensive field surveys conducted in West Africa, and while Lion monitoring efforts have been initiated in all remaining populations, reliable data on current population trends does not yet exist. There is strong evidence for ongoing declines, however. In Senegal's Niokolo-Koba NP, for example, continuing calamitous declines in prey populations are almost certainly causing concomitant declines in Lions (Henschel et al. 2014).These results justify listing of the West Africa subpopulation of Lion as Critically Endangered under criterion C2a(ii). Criterion C1 may also apply, however, due to the lack of reliable population decline For comparison with the previous assessment and conventional delineations of West Africa, we note that there is an isolated resident Lion population of <15 individuals in Yankari NP in central/east Nigeria. There is no longer a resident Lion population in Gashaka Gumti NP (Nigeria), although Lions continue to disperse into the area from Faro NP in Cameroon (Central Africa). Since there is no dispersal between resident populations in West and Central Africa there is no rescue effect (Gardenfors et al. 2001). Using the eastern national boundary of Nigeria for regional division would thus only add the Lions in Yankari Game Reserve (<15 individuals) which would not alter the assessment.

PDF files are only accessible to Friends of the Cat Group. Joining Friends of the Cat Group gives you unlimited access and downloads in the Cat SG Library for one year, and allows you to receive our newsletter Cat News (2 regular issues per year plus special issues). More information how to join here

 

(c) IUCN/SSC Cat Specialist Group ( IUCN - The World Conservation Union)