Fauna Series No. 4

Fauna of the National Parks — No. 4 Ecology of the Coyote in the Yellowstone

CHAPTER VI:
MULE DEER IN RELATION TO COYOTES

COYOTE METHOD OF HUNTING FAWNS

I did not have the good fortune to observe the coyotes in the act of hunting a fawn but have heard many persons state that coyotes systematically chase deer down the slopes and catch them at the bottom. Along the Yellowstone River it has been said that deer have been driven down to the river where other coyotes were waiting to help finish them.

On March 19, along the Yellowstone River below Crevice Creek I had an experience with some deer which may be significant in explaining coyote predation on fawns. Fresh deer tracks in the snow crossed the trail and I followed them up the slope on the chance of seeing the deer and getting a count of the fawns. I had gone but 200 yards or so when I came upon 14 deer, 5 of which I classified as fawns. My observation was hasty for the deer ran off on seeing me, and since the fawn proportion was unusually high, I followed in order to check my count. I again saw the deer crossing a steep open rocky slope but several passed out of sight into a draw before I could get a full count. I noted two fawns that appeared tired, lagging 25 or 30 yards behind the others. At the edge of the draw I found the band of deer only 30 or 40 yards away. They hurried quickly up the steep slope, all except the two fawns behind. One of these kept on, but the other stalled. I hurried upward toward it. After a brief rest it was able to climb a little farther but again stopped, trying to climb but too weak to do so. Another brief rest and it walked forward a few yards more and lay down in a hiding posture with head and neck stretched forward and held close to the ground. I continued to hurry up the steep slope in order not to give the fawn too much time to recuperate. When I was within a few feet it rose, and, finding climbing too difficult, followed a contour of the slope instead. I tried to keep directly below it to force it upward, thinking that if it started down the slope it might be able to run away from me. However, it got ahead in spite of my efforts and swung around down the slope. When it had made four or five creditable jumps I thought it was going to run away. But its legs buckled on the last jump and it went down in a heap, rolling over several times before coming to a stop. It gained its feet before I caught up with it, but after a few more jumps it fell again, rolling and sliding several yards to a stop. It lay perfectly relaxed with its head in a crack between two rocks. I photographed it, and while I was changing film it managed to take two or three more jumps before falling and rolling again. Now it lay utterly exhausted, not even twitching a muscle when handled.

An autopsy revealed clear lungs and liver, and an absence of nosefly larvae. There were a moderate number of ticks, especially on the neck. The animal, a female, was very thin. It was drooling a little but this may have been due to overexertion.

I wondered if I had staged a hunt similar in many details to a coyote hunt. Possibly the coyote harasses a band of deer on the chance of finding a weak animal. The herd moves up the hill and the weak fawns are left behind. Lacking strength to run up hill the fawn runs down the slope. This may explain why most chases are downhill. His weakness causes him to stumble or slip in the rough steep terrain since considerable strength is necessary to brace himself in landing at the end of each downhill jump. The fawn when killed by coyotes may at times be lying utterly exhausted. This is speculative, of course, but seems permissible because of the similarity between my observation of tracks of fawns presumably killed by coyotes and my own "hunt." That there are many weak and ailing fawns during the winter is unquestionable.

Figure 27— Weak deer fawn which was followed by the writer until it collapsed as shown.
The incident is described in the section "coyote method of hunting fawns."
"Crevice Creek, March 19, 1938.

These data have been given elsewhere, but I might mention here that on the day the above observation was made, besides the second weak fawn in the band I was following, one was seen across the Yellowstone River so weak that it was tottering and stumbling. On March 5 another very thin fawn was seen alone, probably left behind when the band moved on, and on April 1 a lone weak fawn was seen.

On February 12, 1938, I witnessed an incident in which the coyotes seemed to be watching a deer herd, possibly seeking an animal that they could run down. All day the air was full of snow and a strong wind was drifting the snow along in swirls, so that tracking was almost impossible and visibility was poor. A half mile above the mouth of Lava Creek I saw, about 1 p. m., a band of deer that had sought the shelter of a grove of firs some distance up the slope of Mount Everts. Three or four hundred yards farther along two coyotes crossed the trail ahead of me and ran up the slope in the general direction of the deer. About a quarter mile further along I met three more coyotes coming out of the creek bottom. They also climbed the slope of Mount Everts, stopping occasionally to watch me.

About 2 hours later when returning I happened to look behind and saw a deer bounding down the slope of Mount Everts to the creek bottom and up on the other slope. The deer appeared to be a yearling doe. I waited a few minutes to see if she was being chased, and then after following her trail for a time back-tracked her up the slope of Everts. The drifting snow made it difficult to keep on the trail but I managed to follow the widely spaced tracks to one of the scattered clumps of trees high up the slope. Tracks of a running coyote following the deer were seen near the grove of trees, but beyond this shelter all tracks were blown away. A little beyond this point in a thick grove of trees, near which I had seen the band of deer from the creek bottom earlier in the afternoon, I came upon 11 deer, four of which were fawns and one a buck. The deer were standing in the shelter of the trees apparently avoiding the strong wind sweeping over the slope. As I approached a few steps nearer the hand, I saw four coyotes run off. One of them had been sitting by a clump of cedar about 20 yards from the deer and the other coyotes had been sitting a few yards lower down. The deer when first sighted seemed unconcerned, and when I approached they moved up the slope only a short distance. It seemed that the deer I had seen crossing the creek bottom had come from this band and had been chased a short distance by at least one of the coyotes. The observations suggest that the coyotes follow the bands of deer at times and thus have a chance to pick up weak animals. I do not know how readily the coyotes would attack a healthy fawn, but it would seem that they would not have a chance to do so if the fawn kept its head and refused to run away from the band. It is possible that through the evolutionary history of the deer, fawns that left the bands were eliminated, thus constantly reducing that tendency. Apparently coyotes are clever in detecting debility in an animal. As winter progresses and weak animals begin to appear, the coyotes seem to quickly form the habit of scrutinizing bands of deer for any such possibilities.

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