By the time the rutting season arrived in mid-October, there were comparatively few Caribou left in the Windy River area. Consequently my information on the subject was derived mainly from Charles Schweder and Fred Schweder, Jr. Weeks before the scheduled season, there were certain manifestations of the sexual urge. For example, on September 5 about 20 Caribou were passing the Bear Slough. The band consisted mostly of does and fawns, but included several middle-aged bucks (with antlers much less than the maximum size) and possibly some younger bucks. Twice I saw one of the animals attempt to cover another, but driving rain and the compactness of the band prevented me from determining the sex or age of those involved. During a trip to the Kazan River, lasting from September 17 to October 1, Fred observed a good deal of fighting among the Caribou--obviously a prelude to the mating season. In Charles’ opinion, these early contests are not very much in earnest; the real fighting begins about October 15. On October 8 Charles and Fred referred to fighting that was going on among a herd of about 100 between Glacier Pond and Lake Charles. Perhaps less than a quarter of this herd were older bucks; the rest, younger bucks, does, and fawns. In former years, while living at the “Old Post” on Red River, Charles used to go out and watch the fighting on a big open muskeg, about a mile square, where the Caribou would congregate practically every year at the rutting season, up to a thousand strong. They would stay for three or four days, then disappear. Nothing on the same scale had come to his notice in the vicinity of the Windy River post. At this season, when the animals are in large herds, the bucks utter their calls, as mentioned in the section on _Voice_. According to Fred, one sees in October a good many bucks with an antler broken off in the fighting. The break generally occurs at about the middle of the antler. On September 29 Charles reported a buck with a broken antler, which he interpreted as evidence of the beginning of the fighting season. During the rutting season he once shot a buck with a broken jaw, and another with an eye gone. The possible inference was that these injuries had been sustained in fighting. A buck secured on October 16 had apparently been wounded in fighting; there was pus in its neck, and it was considered unfit for eating. I heard nothing as to the possible use of hoofs in contests between bucks, as reported by Jacobi (1931: 233) for the Reindeer.