NATIONAL PARK SERVICE Fauna of the National Parks of the United States No. 4 Ecology of the Coyote in the Yellowstone

DISTRIBUTION AND NUMBERS

MUCH desirable information on the distribution of the bighorn (Ovis canadensis canadensis) is still lacking. Although it is known that some of the animals on the Mount Everts winter range summer on Mount Washburn. it is not definitely known where the remainder spend the summer except that some of the rams move to the Gallatin Range. Neither is it definitely known where the bighorn wintering in the Tower Falls area spend the summer. Winter and summer distribution in the northeastern section of the park is not well understood. Much of this information will be important in analyzing the status of the bighorn.

Bighorn are known to winter in the Mount Everts area, along the Yellow stone River from Gardiner to Quartz Creek, on parts of Specimen Ridge away from the Yellowstone River, on Druid Peak, and on Mount Norris and in some nearby peaks. The heaviest concentration of bighorn in winter is in the Mount Everts area, which includes parts of Terrace Mountain and Rattlesnake Butte. Some of these animals wander outside the park on either side of Bear Creek.

On the winter range along several miles of the Yellowstone River between Gardiner and Quartz Creek the bighorn are widely scattered except on the ledges along the Yellowstone River between Little Buffalo Creek and Quartz Creek where probably 60 or more animals can usually be found. In the winter of 1937—38 I saw 17 bighorns on Druid Peak and in the winter of 1938—39 the rangers reported seeing 21 animals in this area, as well as about 30 on Mount Norris and surrounding peaks. The bighorn on Druid Peak and in the Mount Norris area winter up high although most of the others are wintering lower down. The important factors determining the winter range of the bighorn seem to be an available food supply and the presence of cliffs. Much of the range is wind blown, although in some areas the snow does not lie deep. The bighorn paw readily for food and, if feed is present, some snow does not handicap them greatly.

Figure 37— An isolated young ram a short time before he died. The heavy infestation of scab mites, causing loss of long hairs over side of the body and parts of neck, was seen on several young rams in the fall.
Mount Everts, January 16, 1938.

In summer a band of about 30 ewes and usually some young rams are found on Mount Washburn. Some of the old rams from the Mount Everts winter range move into the Gallatin Range for the summer and ewes have been reported summering in these mountains. A number of bighorn summer in the northeast corner of the park but their distribution is not known in detail. Some occur on Cutoff Peak and others in the mountains east of Soda Butte Creek.

It is my impression that the number of bighorn in the park has not varied much in late years. The annual counts have shown an increase but it is probable that this is in part at least a result of more complete counts. However, the animals are holding their own and may possibly be increasing. With the discovery of additional bands in the park in the winter of 1938-39, there will probably be a further increase in the annual census for that year. The official count as made by rangers in the park is as follows for the past 5 years: 1934 (125); 1935 (126); 1936 (118); 1937 (175); 1938 (175).

The number of bighorn in the park is no doubt less than in early times. Large numbers were once found in the Hoodoos on the eastern edge of the park. This was a favorite hunting ground. Many bighorn once lived on the Trident in the Upper Yellowstone Region. Early hunting probably destroyed most of these animals and apparently eliminated bighorn populations which by habit ranged in areas where none are now found.

GENERAL CONDITION OF BIGHORN

In 1937 lambs and some ewes were noted coughing in early August and from that time through the winter months. On September 16, 1938, four of five lambs seen on Mount Washburn coughed violently and frequently, and, in some spells, 20 or more times successively. The coughing suggests a heavy infestation of lungworms. Mills (1937, p. 211) examined the lungs of a 5-year-old ewe and a 4-year-old ram from Mount Everts in the winter of 1934—35, and reported a heavy lungworm infestation in each case. He wrote: "In both cases the lungs bore numerous abscesses, and smears indicated the presence of multitudes of lungworm larvae." Two kinds of lungworm were involved, Protostrongylus stilesi and Elaphostrongulus odocoilei.

Marsh (1938), in reporting on several autopsies and bighorn disease investigations, states that lungworm is a primary etiological factor in one type of pneumonia, and the organism Corynebacterium pyogenes in another type. Potts (1938) in Rocky Mountain National Park also reports these two types of pneumonia. The severe coughing noted among the lambs on Mount Washburn indicates that they may be in danger of pneumonia. Their coughing is so severe that it seems that the physical condition of the lambs would be considerably affected by whatever organism causes the affliction and that the weaker ones are probably subjected to pneumonia.

If some parasite is involved the condition existing on Mount Washburn may favor its spread, for the movements of the bighorn are here considerably restricted by the salt still remaining on the ground which was formerly salted. This thought, however, has not been demonstrated.

Figure 38— This old emaciated ram with a humped up attitude indicating it was ailing was found dead
a few days after this picture was taken.
Gardiner River at base of Mount Everts, March 26, 1938.

Some lambs are doubtless not physically up to par when born. On August 7, 1937, a lamb with its right eye swollen shut was seen on Mount Washburn. This lamb was runty, feeble, and indisposed to activity so that it lagged behind the band when the animals were traveling. It was easily approached on the blind side. Death probably soon claimed it, as it was not seen on the winter range in November. On November 8, 1937, a 3-year-old ram was noted which was blind in the right eye. His general condition was not healthy.

On November 21, 1937, near the cliffs along the Yellowstone River opposite Tower Falls I saw an extremely small lamb with five ewes, three yearlings and a young ram. The band dashed out of sight leaving the lamb following some distance behind. A half hour later when I again saw the band the runty lamb was missing. The band was seen the following day and the runty lamb was still missing and was not seen again that winter. It apparently was not physically capable of moving with the band. The day it was lost I tried tracking it but the area was so trampled over by elk that I lost the trail.

Scabies, caused by the mite (Psoroptes communis ovis), is not uncommon in the bighorn and seems to cause the death of a few of the animals. In the winter of 1937-38 on Mount Everts, two-year-old rams and one-year-old ram had lost much hair over the sides of the body, and behaved as though they were not well. Another ram about 2 years old had lost the hair on one side of the neck, and was seen foraging by himself. One of the rams afflicted with mites and seen alone on January 16 died later in the month. It is possible that the others died for they disappeared in late winter.

At Junction Butte on January 22, 1938, I saw a ewe in a rough coat and a lamb which apparently had scabies in the region of the tail. A lamb, which appeared to be this individual, was seen again on May 9, 1938, and it looked sick. It was humped up and very thin and the loss of hair over the tail region was more noticeable.

In the spring of 1939 between February 25 and March 7 several animals were noted which were not in good condition.

An old ram which had been feeding along the Gardiner River near Gardiner for a couple of months was extremely thin and stood humped up much as did one of the previous year, which later died. A 3-year-old ewe on Mount Everts was blind in the right eye, very thin, and in a rough coat. She was quite restless.

A 3-year-old ram, seen on Mount Everts, was emaciated and in poor coat. It appeared to be infested with mites.

A ewe near Bear Creek, outside the park, was thin and in rough coat. It is likely that these four last-mentioned animals died during the spring. A thin ewe followed by a lamb seemed to have a lame shoulder. She limped, with her body at an angle so that the hind legs tracked to one side of the fore legs.

The Mount Everts winter range was more heavily grazed in the spring of 1939 than I had ever seen it. Still the bighorn seemed to be in fair shape, although they appeared thinner than usual. All lambs, except one, seemed to be in good health.

Figure 39— A magpie sitting on the rump of a ewe. Magpies were often seen on bighorn picking
on various parts of the body as though feeding on parasites.
Mount Everts, November 25, 1937.

BIGHORN DEATHS

Definite records of five dead bighorn were secured during the winter of 1937—38 and I was told that some had been poached outside the park. The amount of bighorn carrion available for food is relatively small. The following is a record of animals found dead.

February 6, 1938, a young ram, about 3 years old, was discovered on the Gardiner River. When first reported by workmen about January 30, the carcass was lying in a small cave located at the base of a perpendicular clay bank near the water. Pieces of the hide were sent to Dr. Harlow B. Mills at Bozeman, Mont. who reported the presence of mites on all samples. On January 16 I had seen a young ram a short distance from the spot where the dead animal was found, and I have no doubt that it was the same individual. When I saw it alive most of the long hair on one side was missing. The fact that this ram was living alone indicated he was sick and lacked the inclination to travel normally in the company of the others.

On February 10 along Glen Creek below Golden Gate I found the carcass of an old ram which had been dragged off a knoll by a coyote. As the meat was not yet frozen, it had not been dead long. The ram was thin, its teeth were worn to the gums, one molar and two incisors were missing, and one incisor was almost worn through from one side. There was some necrosis around the molars. The animal had apparently died from old age.

On March 1, the bones (excepting the skull) and hair of an old ram were found in a gully along the Gardiner River. The animal had probably died from old age or disease.

On April 5, 1938, the remains of an old ram, which I photographed alive on March 26, were found along the Gardiner River. The photograph (fig. 38) shows its emaciated condition. Principal cause of death was probably age.

On May 9 some hair remains of a sheep were found on the rim of the Yellowstone River near Quartz Creek.

Figure 40— Bighorn in foreground, antelope passing beyond them. Antelope frequent Mount Everts
to feed on sagebrush and, in spring and fall, on green.
March 26, 1938.

To summarize: three of the deaths recorded here were probably due to old age, one to mites, directly or indirectly, and one to an unknown cause.

During the winter of 1938-39 one lamb was killed by a car and two rams were reported illegally shot outside the park boundaries. Other casualties, not reported, no doubt occurred.

Apparently bighorn occasionally lose their footing and are thus accidentally injured. A 3- or 4-year-old ewe found in Flat Creek in Jackson Hole was brought intact to O. J. Murie in Jackson. The animal was very fat. The two men who carried the sheep in declared coyotes had killed it, for one of them had shot a coyote at the still-warm carcass. The entire animal was skinned out. There was not a bullet hole or tooth hole in the skin. There were heavy bloodclots under both jaws (skin not broken), and one thigh was badly bloodclotted. Around the opening in the abdomen where the coyote had been feeding was some dried blood in the hair. Evidently there had been a hole there, and that is where the coyote began to feed. Clearly the animal had fallen, perhaps off a cliff, resulting in these serious bruises and actually puncturing the abdomen. It probably went down to the water, feverish, never got up, and a coyote had promptly found it.

During the winter of 1934-35 Dr. Harlow B. Mills (1937) reported the following losses: Shot illegally by hunters, 8; died from shot wound, 1; pneumonia, 1; accidental (cars), 3; collected for study, 1; unknown, 1.

The dead animals recorded in this section and the records of those suffering from ailments and infirmities in the preceding section show the causes of some of the normal losses suffered by the bighorn population.

LAMB SURVIVAL

If coyotes were preying on bighorn, lambs would be the main victims, so a particular effort was made to determine lamb survival. There are, of course, many factors other than the coyote which might reduce the lamb crop so survival of lambs is not necessarily a criterion of coyote predation.

Knowledge of the lamb survival is, however, one of the first steps in learning what factors are important in maintaining the population. This phase of the study deserves much more time than I have been able to give it, but I feel that sufficient information was gathered to indicate some of the probable relationships between coyotes and bighorn.

It should be recognized that there are some difficulties in making a lamb census in winter, and in classifying the yearlings and older animals. Frequently I have found yearlings mistaken for lambs, and yearlings might at times be mistakenly classified as older animals. Lambs vary greatly in size. I have seen a male lamb in winter that was actually as large as a female yearling traveling with the same ewe. I do not wish to over emphasize the difficulties, for after some experience most of the animals can be rather readily classified, even though an animal will often be found which requires careful scrutiny and comparison to be properly identified. The general tendency is to identify yearlings as lambs.

Although I have quite a number of figures on lamb survival, I have omitted discussing several aspects of this question, especially survival of yearlings, feeling that further data are needed.

Season of 1936.—Few observations were made of the 1936 lambs and those were not made until the following spring. On May 16, three ewes, three lambs, and three young rams were seen at Junction Butte. Ranger Condon reported 32 ewes and 28 lambs in the Junction Butte region during the winter of 1936—37. This seems to be a high lamb ratio and possibly a few yearlings were classified as lambs, but as Ranger Condon is an excellent observer I am inclined to believe in the accuracy of his observation. Careful checking in the spring by Condon showed the loss of only one of the 27 lambs and this one was reported killed by coyotes. The condition of the animal at the time it was eaten was not known. Coyotes were plentiful on this bighorn range and were suffering from a shortage of food, yet they apparently preyed on only one lamb during the entire winter and this one may have been sickly.

Figure 41— Bighorn feeding on a range that was closely grazed, mainly by elk.
Loose discarded seed stems of needle grass were the chief food items.
Mount Everts, March 6, 1939.

Season of 1937.—During the summer, three counts, the last one quite complete, were made of the bighorn on Mount Washburn. These animals apparently winter on Mount Everts.

In November some representative counts of the sheep on Mount Everts were made and additional counts were made later in the winter, as follows:

¹ Includes yearlings.

Although the wintering bands on Mount Everts are composed of those summering on several ranges, including Mount Washburn, still the winter lamb count is only about half the summer count of lambs on Washburn alone. The ewe count is larger, as would be expected.

The various counts strongly suggest that there was an appreciable loss of lambs occurring sometime between late summer and the month of November. If predators were responsible for the loss, one would expect losses during the summer when the lambs are most helpless, and also during the winter months, when, as will be shown, there was no noticeable loss. It may be that the lambs that are seen coughing considerably in summer succumb in the late summer and fall. In September 1938 a sick lamb was found on the Gros Ventre Range by a hunter. This incident is in accord with conclusions that may be drawn from the observations made in Yellowstone. Marsh (1938) reports lambs dying at the National Bison Range from acute pneumonia at the age of 2 or 3 months. Another possibility is that the added exertion entailed by migration eliminates the weaker animals during that period, thus reducing the weaker animals over a short period rather than over a long one. It might be suggested that the bighorn in their migration are at times more vulnerable to coyote attack through being away from protecting cliffs. Vulnerability to predation while on cliffs is very low; nevertheless, even on the summer and winter ranges, bighorn are often in contact with coyotes when away from crags. They apparently are able to protect themselves from coyote attacks if necessary when not among cliffs.

The fawns which were on the winter range on January 18 apparently suffered little or no loss during the remainder of the season. On that date 40 ewes, 6 yearlings, and 13 lambs were counted. A few days before the count of 28 ewes, 5 yearlings, and 9 lambs was made on March 26; 4 ewes with 2 lambs were noted at Bear Creek, and 8 ewes with 2 lambs were seen on the north slope of Rattlesnake Butte. It is almost certain that these bighorn had spread out from Mount Everts and therefore in late March there were still about 13 lambs in the Mount Everts population, the same number as in January.

At Junction Butte and vicinity, the following counts were made in the winter of 1937—38:

Apparently the bighorn distribution in 1937—38 varied from that of the preceding winter. This is not surprising in view of the great difference in snow conditions. The counts, I feel, are incomplete for this area but the figures, as far as they go, indicate the winter survival of the two lambs seen on the range on November 22.

During the winter of 1937—38 a total of 193 bighorn was counted and, of about 146 classified into age and sex groups, only 19 were definitely recognized as lambs. There was some possibility of duplication in individuals counted, but it is considered small.

Season of 1938.—During the summer, counts of the bighorn on Mount Washburn were made, two of which were rather complete.

¹ Includes yearlings.

It is evident that the lamb survival during the summer was excellent for the lamb counts made on July 13 and September 2 are the same.

I saw several coyotes near the bighorn on Mount Washburn. The fire guard saw coyotes near them all summer and expressed concern over the safety of the lambs with coyotes so common on the mountain. Of 21 coyote droppings found on the bighorn range on Mount Washburn, none contained bighorn remains.

In the summer of 1938 not a single young ram, older than a yearling, was seen on Mount Washburn, while the preceding summer as many as six were found. It is possible that the young rams were off by themselves, although one would expect them to be found hear the ewes. The young rams seem especially susceptible to scabies. One was known to have died from this affliction, and others were affected the preceding winter. It is likely that some of the young rams in the Washburn population had succumbed to the disease.

During the winter of 1938—39 the following counts were made of bighorn wintering on Mount Everts and on Junction Butte in the vicinity of Tower Falls.

The number of lambs that appeared on the winter ranges in 1938 was about twice the number that came down in 1937. The yearling count was smaller in November 1938 than it was the preceding year. This correlated with the poor lamb crop in 1937 and the apparently high survival in 1936.

On Mount Everts the November lamb count was 23 and the late February count was 17, indicating a possible loss of 6 lambs. It is possible that a few lambs were overlooked for during this period several ewes with their lambs had been seen apart by themselves. They thus may have wandered away from the area where the count was made. A winter survival of 17 of the 23 lambs is satisfactory, and seems especially high after one has examined the poor range utilized. Although all but one lamb seemed to be in fair condition in early March, it is likely that the weaker ones had succumbed. The emaciated lamb seen may also have failed to survive the remaining part of the winter.

The lamb count at Tower Falls was very incomplete. The two lambs were seen with lone ewes off by themselves a half mile and a mile away from the other bighorn, so that it appeared some of the ewes with lambs were living alone. A more extensive count may have revealed other lambs. The figures are too few to compare with the earlier count, which was also small.

If coyotes were an important enemy of bighorn on the winter range one would not expect the high survival of lambs found on Mount Everts during the winters of 1937—38 and 1938—39, for coyotes during both years were abundant in that area. As the bighorn on Everts were frequently found feeding over a quarter of a mile from cliffs, they would have been vulnerable to attack if their safety depended entirely upon cliffs. Although the bighorn often retreat to cliffs when coyotes, man, or any other source of danger is discovered, they sometimes simply bunch up in the face of such danger. The latter action under ordinary circumstances probably is sufficiently protective to make them safe from coyote attack. It is particularly significant that there were no lamb losses so far as known on Mount Washburn during the summers of 1937 and 1938 even though coyotes were common on this summer range and were frequently seen near the bighorn. It is important to consider that much of the time these animals were feeding on open slopes away from any cliffs.

LAMB-EWE RELATIONSHIPS

During the summer the lambs often draw together within a band. A ewe is frequently followed by one or more lambs which do not belong to her. Mothers may leave their lambs with other ewes and go off by themselves to feed. On August 7, 1937, a ewe that had been resting 300 yards from her offspring returned to it, "baaing" when I disturbed the group in which she had left her lamb.

The lambs remain with their mothers through the winter, and are frequently seen nursing during that season. The latest date on which nursing was observed was February 27. On this occasion the mother touched a lamb lightly on its side with a front foot whereupon the lamb turned and nursed, butting vigorously. Yearlings are sometimes found with a ewe during the summer and fall when they are almost a year and a half old.

Although I have seen a ewe followed by two or more lambs, I have never been sure of an instance in which more than one lamb was her own.

Figure 42— Protected study plot, showing contrast with unprotected range closely grazed during the winter of 1937-38.
Mount Everts, April 8, 1938.

BIGHORN-MAGPIE RELATIONSHIPS

The magpie is probably not an important factor in the status of bighorn but may be of more significance than is now apparent. There have been cases when domestic sheep have been harmed by the magpies pecking at wounds, enlarging them and keeping them raw. No instance of this kind of magpie activity was noted on the bighorn. However, on a number of occasions magpies were found perched on them, busying themselves chiefly around the tail region and in the ears. I tried several times to collect a magpie immediately after it had been feeding on a bighorn but without success. Since mites are often present in great numbers in the ears and also over the body, it seemed probable that the magpies were feeding on these parasites. The bighorn usually acted as though they were oblivious of the presence of the birds but occasionally seemed to resent it. Once a young ram turned suddenly and tried to butt the bird. If the magpies are feeding on mites, their actions are beneficial to the bighorn.

It might be mentioned that magpies are also frequently found perched on elk and deer. At Wind Cave National Park one of these birds was seen perching on a bison. The stomach contents of a magpie collected near some deer consisted of three engorged ticks and the intestinal contents consisted of tick fragments. Ticks were found in the stomach of a magpie found dead. The tick infestation on the elk and deer is so heavy that the activities of the magpies can hardly be sufficient to reduce the infestation materially, but certainly this habit tends to be beneficial to the elk, deer, and bighorn. Moreover, in the case of bighorn, if the magpies consistently seek out the ear mites, which are troublesome to many of these animals, the birds are performing important service.

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.

STATUS OF BIGHORN

During the winter the bighorn, especially in the Mount Everts region, subsist mainly on grass, but also feed on a variety of shrubs and trees such as willow, greasewood, sagebrush, fringed sage, yellowbrush, and Douglas fir. The stomach contents of a ram that died near Golden Gate consisted of 50 percent Douglas fir, and animals were several times seen feeding on fir branches which had fallen to the ground. Sagebrush and other shrubs were eaten extensively in November before snow had fallen on the grasses, and on Junction Butte and vicinity large quantities of yellowbrush were eaten during early November.

In winter, the bighorn are in direct competition with the elk for practically all food plants, and with the deer and antelope for the browse plants where their ranges overlap. The competition for food each winter is severe. On Mount Everts the bighorn during the last half of the winter subsist on a range so heavily utilized that the elk for the most part avoid it, after taking the "cream" of the forage. The bighorn in late winter pick at discarded seed stems lying on the ground and at the already closely grazed grass. The natural diet of the bighorn is more varied than the present vegetation on Mount Everts permits. A diet of greater variety would probably be more balanced in food values and result in healthier animals more resistant to diseases.

The grass slopes of Mount Everts were apparently once largely covered with sagebrush, remnants of which still remain in the form of dead roots and broken stalks. Now sagebrush is found only in hollows and ravines protected in winter by heavy snows. Destruction of the sagebrush was brought about by the combined feeding of bighorn, antelope, deer, and elk. When present it served to insure a good grass growth by retaining the snow, and shading the ground in summer so that surface evaporation and run-off were retarded. The nearly complete utilization of the grass each winter is adversely affecting the grass stand and is increasing erosion. A protected plot on the Mount Everts range showed clearly, in the fall of 1938, that heavy grazing was deteriorating the grass stand. The grass within the plot which had not been grazed for about 4 years was luxurious, while that outside was sparse and showed poor growth. So heavily is the range grazed in winter that no dead vegetation is left on the ground to retard run off and evaporation during the growing season. Hence the growth is poor if moisture does not fall regularly. As a result of the heavy grazing on the range, not only is the grass stand deteriorating but sheet erosion is quite evident. The heavy use not only affects the bighorn's supply of food each winter but also reduces the permanent carrying capacity of the range.

In the Tower Falls area, Douglas fir on the bighorn range is overbrowsed, but the grasses and low plants are not greatly injured. They are protected from over use by deep snows and a smaller concentration of animals, and the cooler climate makes them less subject to drought and heat during the growing season. On this range the bighorn suffer somewhat through other forms of competition from the elk. In the fall of 1937 large bands of elk were seen feeding on grasses and yellowbrush on the narrow strip of range along the rock rim above the Yellowstone River, which is the important part of the range for bighorn. Although the vegetation was only partially consumed, enough was eaten to make considerable difference to the animals when they pawed through the snow for food in midwinter.

Condition of the ranges is an important factor to consider in discussing the status of the bighorn. Disease, in many cases, is the result of poor range, and poor range would probably always augment the extent of disease. As yet the effect of poor range on bighorn reproduction is unknown. There is a possibility that inadequate nutrition in winter might reduce the lamb crop or produce lambs with lessened vitality. The bighorn are afflicted with mites which each year destroy a few animals. Many, especially the lambs, have a severe cough, the causative organisms of which may also be taking its toll. To minimize the effects of disease it is important to improve the range and to discourage congestion of the animals over a small area for any length of time. Resort to such devices as salting should be avoided.

Poaching is a factor in holding down the number of bighorn on the Mount Everts area. A few bighorn occasionally move outside the park into territory along the Yellowstone River where the animals are known to have been poached in the past. As many as 15 animals consisting of nine large rams, three ewes, two lambs, and one yearling have been seen outside the park at one time. During the winter of 1934-35, eight from the Mount Everts population were killed by poachers just outside the park, and another died from shot wounds. Some bighorn were said to have been illegally shot during the winter hunting season of 1937-38. Later I found no evidence of bighorn poaching but did discover in the areas occupied by bighorn just outside the park boundary, the legs and head of a fawn deer that had been slain in the early spring. Two rams were reported illegally killed outside the park in the winter of 1938-39. Where a population is barely holding its own, a small but steady drain may be sufficient to keep it from increasing.

During the last 2 or 3 years the bighorn population has held its own or possibly increased slightly. In view of the lack of forage in the Mount Everts area there is hardly room for more bighorn on that important winter range. There is a strong indication that the lambs are affected by some disease or parasite causing a severe cough, which, judging from the scarcity of lambs appearing on the winter range, may be eliminating some of them during the fall. The data obtained from the coyote droppings, from observations of the coyotes on the bighorn ranges, and from lamb counts at various times, indicate that coyote predation is at most an unimportant mortality factor, this in spite of a large population of coyotes on the big horn ranges.