REMAINS of adult antelope (Antilocapra americana americana) were found in 21 coyote droppings, and remains of fawns in 32. A total of 1,657 droppings were gathered on the antelope range. Considerable concern has been expressed over the welfare of the antelope, it being strongly felt by many that the coyote was a threat to its existence in Yellowstone. For this reason, factors affecting the antelope were carefully studied. Not only was the coyote pressure on antelope and the survival of fawns noted, but also such other factors as condition of the antelope winter range and competition from other game animals.
The winter range of the antelope in the park consists of the sagebrush areas from Reese Creek to and including the lower slopes of Mount Everts and to Rattlesnake Butte on whose steep slopes some antelope are usually found all winter. In 1930 Ranger J. L. Greer in his November report stated that 93 antelope were seen on the bench lands outside the park north of the Yellowstone River in the vicinity of Bear Creek. The following month Ranger Allyn Hanks reported seeing 64 antelope in this area. It was unusual for this species to be found here even though the range is better than within the park. During the winter of 193738 a few antelope were occasionally found outside the park below Reese Creek. In the cold months of 193839 the majority of the antelope herd moved outside the park below Reese Creek, where there is good winter range. It is possible that the rather close confinement of the antelope to the poor range in the park during the past few years may in part have been due to poaching outside, although habit may have been a more important factor.
Sagebrush (Artemisia tridentata) forms the staple winter diet of the antelope. It is eaten at all seasons but in winter is particularly sought. In March, when the snowdrifts in the hollows had melted sufficiently to expose the tops of the sagebrush that had been protected by snow during the winter, the antelope were frequently seen wading into the drifts to feed on it, since elsewhere it was closely browsed. Atriplex oblanceolata is also an important winter food, especially if the snow is so light that it does not cover this low-lying plant. Although even more palatable than sagebrush, Atriplex oblanceolata is far less important as a winter food because it is much less abundant. Yellowbrush (Chrysothamnus), and greasewood (Sarcobatus vermiculatus), are frequently eaten but rate lower in palatability than sagebrush and Atriplex oblanceolata, and are not so widely distributed over the winter range. Russian thistle is heavily consumed wherever found.
Other species are eaten in winter, such as fringed sagebrush (Artemisia frigida) which would be of more importance if it were not so scarce. Discarded Douglas firs on the Mammoth dump, which had been used for Christmas trees, were eaten, but consumption of living fir was not noted elsewhere. No fir is available except in fall or early spring on the edges of the range. In late fall and early spring some green grasses are available and are highly relished.
In winter, no evidence of feeding on dry grasses was noted; and if any grasses are eaten the amount is slight. It is important to remember this in order to avoid misleading calculations dealing with antelope food on winter range in Yellowstone. For instance, several years ago sagebrush on sample plots on the antelope range was grubbed out to learn whether the grass could be increased.
On the antelope winter range, considerably more than 75 percent of the sagebrush is dead as a result of overbrowsing. In some places there is not much evidence of its former presence but elsewhere the dead stalks stand or lie broken loose. Figure 36 shows the position of a fence along the old park boundary which from about 1902 to about 1932 prevented the antelope to some extent from moving out of the park. Although the fence has been removed the sagebrush is now largely dead on both sides of the old fence line but that to the north (right) of the line is more in evidence because it was overbrowsed later, therefore is not so broken down and some is still alive. Nearly all sagebrush on more recently acquired park lands as far as the new boundary at Reese Creek is dead.
In past years the antelope have generally been confined to the winter range within the park, and during the winter of 193738 only a few of them were ever seen below Reese Creek outside Yellowstone. In the winter of 193839 the antelope moved outside enmasse to better range north of Reese Creek. In November more than 200 were seen north of this creek, and on March 1, 1939, a total of 495 were counted there. No doubt some actually present were missed in the count. Shortage of food within the park was probably the main reason for the general exodus.
The poor range conditions in the park were aggravated by an unusually large amount of snow lying on the ground all winter.
At the present time, antelope are the heaviest utilizers of sagebrush on their range as a whole, but at the borders of the range deer consume large quantities. The deer range overlaps a portion of the antelope range, and since deer in winter are heavy feeders on sagebrush there is direct competition for food. A few deer may be found wandering out in the middle of the antelope range but most of them are found on the fringes, in the Game Ranch area and on the lower slopes of Mount Everts along the Gardiner River. Bighorn and antelope compete for sagebrush and other plants and now most of the sagebrush has vanished from the more exposed slopes where bighorn are found. Elk feed on sagebrush in small quantities, not from necessity but because they relish it, as shown to a certain extent by the fact that they eat it early in the fall before any snow has fallen, when other palatable foods are available. The quantity of sagebrush consumed by large bands of elk may be considerable. For some time, apparently, a number of elk have wintered on the antelope range and nearby and have probably contributed a little to the overbrowsed condition of the sagebrush. At the present time elk are attracted to the antelope range by fields of brome and wheat grasses, planted on the former cultivated lands at the Game Ranch in order to keep the soil from blowing away. During the winter of 193738 between 800 and 1,000 elk visited the fields each night, returning to the forested foothills for the day. En route to and from the fields, evenings and mornings, the elk browsed on sagebrush. It had been eaten so closely that there was little available, but enough elk were congregated to have done considerable damage if a good stand had been present. It is hoped that less luxuriant native vegetation may soon take over the hay fields which are now such an attraction to elk, whose presence there in large numbers is injurious to the antelope range.
In April, and sometimes earlier, the antelope move up-country from the Game Ranch wintering area, while deep snowdrifts still lie in the hollows and on the north facing slopes. In summer they are distributed from the Game Ranch all the way to Tower Falls and to the high grassy ridges bordering Cache Creek on the east. They are commonly found on top of Specimen Ridge. In the summer of 1938 at least one hundred antelope stayed on the winter range in the Game Ranch area. These animals were thus remaining the year around on the same range. In August 1935, I saw three antelope in Hayden Valley. This occurrence was unusual, although in the early days the species regularly summered there. In early November the antelope move back to the winter range.
The fawns are born in late May and early June. On May 28, 1938, 10 of 12 does were still obviously heavy with calf; a day later a fawn was found; on the thirty-first most of the does seen, although scattered out singly, still seemed heavy with fawn; on June 4, three does were with fawns; on June 7, two fawns were found which had been born during the day; on June 10 a doe, still heavy, was observed. It was my impression that by June 10 most of the fawns had been born, but that very few arrive before May 28. Twinning is not at all unusual. Between June 4 and June 11 six does were seen with twins and seven with a single fawn. Some of the does with a single fawn may have borne twins.