Nothing is more surprising than the effect of the movement of civilisation westwards upon the number of the animals who were accustomed to exist upon the prairies. The explorers who passed through these waste lands in the beginning of the nineteenth century, reported that the surface of the country, especially near the river Platte, was often blackened by immense herds of bisons. Fifty years later when I went over the same ground no buffaloes were to be seen there, and they no longer frequented that part of Nebraska. The rattlesnakes have also almost disappeared in consequence of the introduction of animals that were hostile to them.[42] The manner by which this destruction of the snake tribe has been carried out, was brought to my notice when I was crossing Lake Erie. Near the west shores of the lake there were several islands which had been infested with reptiles to such an extent as to make it dangerous for men to land upon them. A resident who had lived for many years upon the adjacent shore, and who happened to be on board the steamer when we passed near one of the largest of the islands, told me that in order to clear the ground a large number of hogs were landed upon it, and within a short time the island was made perfectly safe. It was observed that they rushed immediately forward and when close to the snakes they dropped upon their knees and commenced to devour them with the greatest avidity. The darting of the fangs upon them did not seem to have the slightest injurious effect. It is therefore probable that this strange invulnerability of the hog is due to the thickness of its hide, and the close stiff bristles which prevent the penetration of the poison. On the prairies, the explorers mention their having seen, besides buffaloes, deer, hares, wolves, eagles, buzzards and ravens. I saw several herds of antelopes and a few wolves: one of them belonging to the coyote species was observed in the evening to be prowling round the huts of settlers at the forks of the Platte. It was caught and forthwith dispatched. It was a good sized wolf with a thick coat of shaggy iron-grey hair and looked fierce and savage. On the banks of the southern branch of the river near this spot I joined an American companion in an expedition to look for prairie grouse. We found them amongst the brushwood in considerable numbers, but the birds were wild and it was difficult to get within range of them. The Platte at this part was nearly three thousand feet above the sea. On the desert, at a height of seven thousand feet, I saw antelopes grazing upon the prairie grass which was growing abundantly and afforded ample supplies of food for them. Wolves were also on these plains skulking in the vicinity doubtless hoping to appease their hunger before many hours had elapsed. These wide and lofty table lands were the ancient hunting grounds of the Dakotas and Cheyennes.