BISON: Distant Thunder by Douglas Gruenau (Takarajima Books: $ PRICE ?? , 104 pp., paperback original). The bison is the largest land animal in North America, and the estimated 70 million of them that inhabited the Great Plains may have been the greatest animal herds ever to roam the planet. By 1902, over-hunting had reduced their numbers to a few hundred, a figure that has now risen to about 120,000. Working in three U.S. National Parks, Gruenau photographed the remaining wild bison, from birth through maturity, mating, aging and dying, in a handsome paean to a unique natural legacy.