Two surveys; [2-3] provided the first real estimates of the African lion population with some ground-truthing. The African Lion Working Group, a network of lion specialists affiliated with the IUCN/SSC Cat Specialist Group, conducted a mail survey and compiled estimates of 109 known African lion populations. The ALWG African lion population estimate is 23,000, range of 16,500 - 30,000 [data collected in 2002 and published in 2004] although not included were lion populations of known existence but unknown or un-estimated size.
The second survey was carried out by Philippe Chardonnet and sponsored by the International Foundation for the Conservation of Wildlife and Conservation Force. He compiled estimates for 144 African lion populations, grouped into 36 largely isolated sub-populations. His methodology included extrapolation of estimates of known populations into areas where lion status was unknown, and his total figure is larger: 39,000 lions in Africa; range of 29,000 - 47,000.
It is important to realize that these numbers are based on various categories of what can best be described as “guesstimates”. Bauer and van der Merwe’s data, for example, are about 76% based on some category of estimation. This is not surprising, as lions are difficult to count accurately. These large predators occur at low densities and individual recognition is difficult, relying on considerable photographic evidence and expertise. Several survey techniques are available but have been used in very few known geographic locations that lions still occur as they are both time-intensive and expensive. Despite such shortcomings, African lion numbers are accepted by most experts to be in sharp decline.