American Alligator: Ancient Predator in the Modern World by Kelby Ouchley University Press of Florida 4 stars David Wilson Given that its brain weighs about 14 grams, the American alligator has done well. Starting out as "shieldcroc" - the last common ancestor of the modern alligator, caiman, crocodile and gharial - it has evolved into the keystone of the southern swamps, according to naturalist Kelby Ouchley. Ouchley is refreshingly free from scientific stuffiness. Just look at how he begins his profile of America's largest reptile. "I suppose it could be said that because of an alligator my father almost lost his life when I was nine years old. While inspecting a pipeline from a helicopter in the vast Louisiana coastal wetlands, he noticed a female alligator near a nest and asked the pilot to swoop in for a closer look," he writes. For unknown reasons the helicopter crashed at the nest site. "This event only fuelled my budding curiosity of all things associated with the natural world." Mapping the rise of the resilient 200-million-year-old relic that most absorbs him, he notes how it neared extinction in the 1960s. Then, over the next two decades, it rallied, boosted by legislative intervention. Now, the formidably adaptable apex predator makes a staunch contribution to the ecosystem, Ouchley writes. In Florida, the mucky holes that the American alligator scoops out with its snout supply food, water and shelter for a spectrum of species. In Louisiana, the reptile slashes the population of rodents that overgraze marsh vegetation. Because its loss would harm biodiversity and derail the ecosystem, the alligator must be conserved, Ouchley argues. But the US Fish and Wildlife Service dropped the reptile from the endangered list in 1987 and now regulates the legal trade of the species and its products - a risky policy, says Ouchley: human intrusion still threatens the alligator and its southern wetland home. Our lack of respect for the species is shaped by cultural demonisation - an inclination to treat "gators" like sharks or rogue lions, he says. "In novels, alligators are almost always depicted as cunning maneaters and dressed with just enough factual natural history to nurture the otherwise unrealistic image," Ouchley writes. His captivating document shows that, as usual, the real demon is man. Gators are nicer and brighter than they appear, it seems. A telling detail: Ouchley presents evidence that shows they can orient using stars.