Some are so isolated that quibbling over our criteria for land use change would make no difference: the animals that remain are a very long way from individuals that might rescue the population demographically or genetically. A good map is necessary, but it is not sufficient An obvious caveat is that areas for which we detect little conversion of savannahs to croplands may still suffer human impacts that make them unsuitable Vorinostat for lions. Over-hunting for trophies, poaching—of lions and of their prey species—and conflict with pastoralists may not have any visual signal to satellites. Even where there are low human population densities and areas designated as national parks, there need
not be lions within them. The poor performance of even large protected areas in West Africa is striking.
For example: Henschel et al. (2010) surveyed Comoé, West Africa’s largest park, a World Heritage Site that is roughly half the size of Kruger National Park in South Africa. Whilst Kruger holds nearly 1,700 lions (Ferreira and Funston 2010), and much of Comoé looks to be free of human disturbance from the high-resolution Small molecule library imagery that Google Earth provides, Henschel et al. (2010) found no lions, few native mammals, and extensive evidence of selleck compound poaching and grazing by domestic livestock in Comoé. Size alone does not protect even the largest parks if they suffer poor management (Bauer et al. 2003). Satellite imagery does pick up recently burned savannahs, sometimes covering hundreds of square kilometres. These could be natural or set by pastoralists to improve grazing. Analyses of the conservation consequences of anthropogenic fires are available for moist tropical forest against a backdrop NADPH-cytochrome-c2 reductase of protected areas (see Adeney et al. 2009). We have not yet analysed available global data as a means to assess pastoralists’ impacts on the savannahs and how protected areas modify those impacts. Conversely, we cannot exclude the possibility that lions might still be able to move through
areas with land-use conversion, though much experience suggests that they suffer high mortality when they do. For example, Woodroffe (2000) estimated a mean human population density threshold at which lions went extinct of 26 people per km2. Many mechanisms might underpin this threshold, but land-use conversion is the most plausible. The match between her threshold and ours is striking. Finally, even within suitable habitat, lion densities vary greatly (see Chardonnet 2002). Densities of prey also vary widely when considering the variation in rainfall and soil type across lion range (Coe et al. 1976; East 1984; van Orsdol et al. 1985; Hayward et al. 2007). Lion population estimates Our lion population estimate of 32,000 lions is higher than the population estimate by Bauer and Van Der Merwe (2004), but lower than the estimate by Chardonnet (2002).