Fauna Series No. 4

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

CHAPTER VIII:
BIGHORN IN RELATION TO COYOTES

BIGHORN-COYOTE RELATIONSHIPS

During the winter of 1936—37, according to Ranger Condon, of 28 lambs in the Junction Butte area all but one survived. One yearling in late spring was reported killed by coyotes. The soft snow conditions prevalent all winter made travel difficult for coyotes, thus putting them at considerable disadvantage in hunting.

On November 21, 1937, I watched a band consisting of five ewes, one young ram, one lamb, and three yearlings lying on a low knoll 60 yards from the precipitous cliffs opposite Tower Falls. A coyote appeared over a rise 60 yards from the animals and walked slowly toward them. The bighorns watched it for a few moments, then all but a ewe arose (she also arose a moment later) and galloped toward the cliffs, stopping near the brink to feed, after briefly watching the coyote. The latter continued on its course parallel to the cliffs.

On Mount Washburn coyotes were frequently seen near the ewes and lambs summering there, but seemed not to molest them.

On Mount Everts on November 17, 1938, there was a band of eight large rams standing close together and about 40 ewes and lambs spread out on the open slopes below them. Suddenly all the ewes and lambs started running, assembling in two bands. They watched a coyote that had trotted into view and was on his way down one slope and up another slope near the bighorns. A lamb that had been off by itself some 60 yards away galloped up to the band of rams and stood among them. Here it gazed after the coyote, which passed within 100 yards of the ewes. As soon as the coyote was out of sight, the lamb joined the ewes and other lambs who immediately spread out to feed again.

On November 21, 1938, on Mount Everts, a coyote trotted past 50 or 60 bighorn, which ran together in groups and watched the coyote until it passed out of view. Later in the day, a lone deer came trotting up the same slope. The bighorn became as startled as when the coyote had appeared, and assembled at a gallop into two groups. As the deer approached one group, the sheep hastened down the slope. The deer followed them, jumping, and seeming as bewildered as the bighorn. They stopped on a bench, the bighorn moving away from the deer, which soon went over the rim. In view of this last incident, it is a little difficult to interpret the reactions of the bighorn toward coyotes. It is probable that the former, especially the lambs, must run together for protection from coyotes or other predators. The deer was an unusual intrusion on the slope, so the bighorn behaved as they would if any potential enemy were approaching. Once a flock of about 150 rosy finches swooped down over four ewes, causing them to break into a gallop. The reaction of bighorn to any startling occurrence, including coyotes on some occasions, may be a measure of protective reaction to prevent predation.

H. B. Mills (1937, pp. 205—12) wrote concerning predation:

Losses from predators must be quite small on the winter range. The abundant coyote is at present the only predator of any importance to the sheep in the park. Although coyotes were commonly seen about the bighorn, there was no actual evidence that they made attacks on the flocks.

Figure 43— A healthy lamb pawing for short Russian thistle. Bighorn readily pawed through 14 inches of snow.
Mount Everts, February 9, 1938.

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Last Modified: Thurs, Dec 20 2001 10:00:00 pm PDT
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