European bison, which associate in large herds, are essentially forest animals, although the forest they inhabit must be comparatively thin and intersected with glades and meadows where the herd can graze. The neighbourhood of water is also essential; and when muddy pools are available, they are utilised for wallowing. In addition to taking these mud-baths, bull bison in summer are fond of rolling in sandy or dusty spots. Leaves and grass form the greater portion of the food of the Bielowitza herd in summer, one particular kind of grass, known as zubr-grass, being a special favourite and communicating to the animals themselves an aromatic odour. Young shoots, twigs, and bark, especially those of the ash, are also largely eaten; and in obtaining bark the stems of trees are frequently stripped as high as the animals can reach, while numbers of saplings are trampled down. Except where they are artificially fed, bison have to depend almost entirely upon buds, twigs, bark, and patches of dry grass and bracken for sustenance; and at this season the herds leave the damper parts of the forest to take up their quarters in the driest situations they can find. Although an adult bull bison is more than a match for any wolf that ever existed, the Bielowitza herd is constantly harassed by the attacks of wolves, bears, and lynxes, which kill many of the calves, and probably also overpower weakly and half-starved cows in winter, especially if the wolves hunt in packs. Bison feed chiefly in the early mornings and evening, although they may be seen abroad at all hours. During the breeding-season, in August and September, fierce combats take place between rival bulls for the mastery of the herds. When disturbed or alarmed, the herd breaks into a quick trot, which soon develops into a heavy lumbering gallop; and there is scarcely a finer sight in the world than a charging troop of these magnificent beasts. THE GAZELLE (_Gazella dorcas_)