The experiment was made with all the forms of fence that could possibly be obtained or built with the limited resources of a new country. A long lane was first built, with sides 7 feet high, made with poultry netting of a small mesh. Fourteen cross fences of heights from 30 to 66 inches and of various designs were built at intervals along the lane. They were arranged so that the coyotes, introduced at one end of the lane, should have presented to them gradually increasing difficulty in passing the fences. Two coyotes were released singly into the lane, and their progress and methods of passing the cross fences were carefully noted. One was badly frightened by the presence and noise of dogs and men, but the experiment with the other was not made in public. The coyotes ran with their noses close to the ground and seemed to have no knowledge of jumping. Neither of them succeeded in getting over a fence more than 36 Inches in height. The method was one of climbing, assisted by the hind feet, rather than of jumping. All attempts to pass the obstructions began with efforts to get the muzzle through openings. If the entire head could be thrust through and there was enough room for the shoulders to spread out laterally, the whole wolf was able to follow. Both went through rectangular openings, 5 by 12 inches and 5 by 8 inches, but the larger animal failed to pass a mesh 5 by 6 inches. The smaller animal went through an opening 4 by 12 inches and another 5 by 6 inches. Had these openings been triangular in form the animal could not have passed through. The following conclusions were drawn from the experiments: 1. Prairie coyotes will not willingly jump over a fence above 30 inches in height. 2. They will readily climb over fences built of horizontal rails or crossbars, especially in order to escape from captivity. 3. Barbed wires do not deter them from crawling through a fence to escape. Whether they would go through a closely built barbed wire fence to attack sheep or poultry is still an open question. 4. Woven wire fences should have meshes, when rectangular, less than 6 by 6 inches to keep out coyotes. For such fences triangular meshes are much better than square ones. 5. In fencing against coyotes with woven fences care must be used to see that there are no openings at the ground through which the animals can force themselves, since they are more likely to crawl under a fence than jump over it.