What would Africa be without the king of beasts? There may be as few as 23,000 lions left on the entire continent—down from 200,000 in 1975 and 400,000 two decades before that. Susan Hack reports from Botswana and South Africa on the trophy hunting and habitat loss that threaten the most majestic animal on earth—a superlative made plain by the portraits of photographer Nick Brandt

In early January, rain transforms the sandy plains around Botswana's Selinda SpillwayI into a green animal paradise. Water is plentiful, and thick grasses provide cover for the impalas, wildebeests, and red lechwe that give birth in this food-rich season. Although the grass stands taller than our Land Cruiser's hood, guide Motsamai Morundu manages to spot some beautiful, rare creatures. A cheetah mother and cub scan the world from the ledge of a termite skyscraper; three bat-eared foxes snap up winged ants that emerge with the rain to fly for a day; and a tabby-sized African wildcat with a spotted gray coat and black-sock feet pounces after a lizard. In a moment of hilarious serendipity, we park for sundown gin and tonics and witness the birth of a dung beetle brood: The Ping-Pong ball–sized insects clamber out of their nursery of dried elephant poo and take off into the dusk like miniature buzzing helicopters.

I've come to Botswana hoping to see the one species everyone expects to encounter in Africa: lions. Two lionless days pass, and my binocular-strained eyes start playing tricks on me. Lion ears poking up from the grass turn out to be the jagged brown crest of another termite mound. A sleeping lion's belly is nothing more than a yellow log.

I am staying at Zibalianja Camp, a twenty-minute Cessna ride north of the Okavango Delta, on the eastern edge of a 334,000-acre private game concession between the Selinda Spillway and the Linyanti Swamps. My tent sits beneath an African ebony tree that rises like a lighthouse on a sea of grass known as the Pan of Lions. Abundant game, low tourist density, and some unusual lion behavior make northern Botswana the best place in all of Africa to observe the king of beasts. But as I've been learning, the species is in more trouble than most safari clients realize.

A 2006 estimate by the World Conservation Union puts the number of lions left on the entire African continent at 23,000 to 39,000, down from a 1975 report of 200,000, which in turn stated that the lion population had probably fallen fifty percent since the 1950s. A more optimistic 2002 survey funded by Conservation Force—a pro-hunting organization with a vested interest in citing higher numbers—states with strange specificity that there are 28,854 to 47,132 lions in Africa. All these figures may be off the mark, since lions are difficult to count in the wild, sleeping in thickets or tall grass for most of the day and completely inaccessible in some regions. But consider this: Even the most optimistic estimates mean that all of Africa's remaining lions could fit inside a single pro football stadium.

African lions are not in the same "critically endangered" category as Asiatic lions (just three hundred survive, in India's Gir Forest) or Siberian tigers (there are fewer than four hundred). But scientists agree that escalating habitat loss to humans has made them more vulnerable than ever. According to the Conservation Force study, of the thirty-four African nations in which lions are found, only three—Botswana, South Africa, and Tanzania—have populations numbering more than a thousand.