Fauna Series No. 5

Fauna of the National Parks — No. 5 The Wolves of Mount McKinley

CHAPTER THREE:
DALL SHEEP (continued)

Disease and Parasites

ACTINOMYCOSIS

From an examination of the skulls, it is obvious that the sheep are subject to two diseases, common among big game animals, which are known as actinomycosis and necrotic stomatitis. These ailments are described in detail on p. 117. Much of our information on necrotic. stomatitis was secured among the elk in Jackson Hole, Wyo., where it was also found among the deer, bighorns, and moose. In the case of elk, many calves are subject to it. Death among them is often rapid, occurring before the lesions have affected the bone tissue. Many older animals which have recovered are often left with serious dental deformities or loss of teeth. The annual loss among the elk due to necrotic stomatitis apparently becomes more severe during years of food scarcity. The data available indicate that the Dall sheep may be affected by this disease in a manner similar to the elk. The annual loss due to this disease is not extensive.

LUNGWORM

In the lungs of a yearling collected April 24, 1939, and examined by Dr. Frans Goble, numerous eggs, larvae, and adults of a nematode were found which apparently belonged to the genus Protostrongylus or a close ally. (Goble and Murie 1942.) This is the first record of lungworm in the Dall sheep, but the parasite is probably common among them. Lack of previous records is probably due to lack of material for examination. Lungworms might affect the health of some animals, but no data on this were secured. Coughing, so prevalent in the sheep in Yellowstone National Park and Jackson Hole, Wyo., was not observed.

SCABIES

No animals were seen which showed any evidence in the appearance of the coat that scabies existed among them. No mites were found in patches of hide examined. Scabies is quite prevalent among some of the Rocky Mountain bighorns.

A SICK LAMB

About the middle of June 1940, a sick lamb with its mother was seen by a ranger at a tributary of Igloo Creek on the east side of Sable Pass. The lamb was too weak to walk, and saliva drooled from its mouth. It was carried to the creek where it was seen the following day, unable to rise. When I learned about the incident the lamb was gone.

LAMB DIES IN CAPTIVITY

In April 1929, three weak ewes were rescued from starvation. Two lived and gave birth to lambs at Park Headquarters. One of the lambs did very well, but the other died on the second day after it was born. When it was discovered that the ewe had no milk it was too late to save the lamb. Possibly this type of tragedy accounts for the loss of some lambs at birth in the wild, especially after hard winters.

INSECTS SOMETIMES ANNOY SHEEP

On a few occasions flies were observed annoying the sheep considerably. On July 26, 1940, among the rock chimneys near Sable Pass all the sheep had sought the shade to avoid the large flies which were attacking them. Sheep out in the sun, where they had moved when I disturbed them, were much troubled by these pests. In desperation they would hurry to the shade of a rock. A ewe climbing a long slope opposite me was much bothered by flies, and stopped in the shade of the first cliffs she reached. An old ram lying in the shade was directly in the route I planned to follow to climb out of some rough cliffs into which I had descended. He moved off at my close approach, but when the flies attacked him in the sun he suddenly hurried back to the shade near me. As I approached him he faced me and looked as though he might hold the passage at all costs.

On July 19, 1939, I saw a ewe stamping her foot and watching an insect buzzing around her. She dashed rapidly away, then stood perfectly still, apparently waiting to see if the fly had followed, Three times I saw this performance, in which the sheep behaved much like a caribou when attacked by a botfly.

As a rule the sheep did not seem to be greatly bothered by flies. On the high ridges there is generally enough breeze to greatly minimize this annoyance.

Mosquitoes are said to have attacked some captive sheep at Park Headquarters, but it is not probable that they are of much significance in the sheep hills, where they usually are not plentiful.

Accidents

In 1939 a number of crippled animals were observed. Strangely, no cripples were seen the following two summers except one which had been snagged and was found dead. This difference was due in part to the greater time spent among the sheep in 1939, and possibly, in part, to lighter wolf pressure on the sheep in 1939. The animals injured will be enumerated in order to give an idea of some of the accidents to which sheep are subjected and to show that there is a certain percentage of obviously vulnerable animals, and some accidental casualties.

A lone yearling was found near the road (on April 24, 1939, and it was so weak it could barely rise. When it did get to its feet it stumbled toward me (probably because I was between it and the rocks) and fell at my feet. The hoof of one forefoot was elongated, showing that it had not been used for a long time. One rib was broken and the area around it festered and bloodshot. Other spots showing serious suppuration were the injured foot and the knee, and two spots along the spinal column. There was a sore on each side of the upper palate and sores around the lips. The bruises and broken rib suggested that the yearling had fallen in the rocks.

Figure 29: A yearling sheep, whose right foreleg had been injured, apparently by a fall. The foot had been so little used that the hoof had grown long. [Polychrome Pass, April 24, 1939.]

On May 13, 1939, a ram about 5 years old had a decided limp on a foreleg.

On June 18, 1939, a young ram on the east side of Cathedral Mountain was lame in a foreleg. When the animal fed, it either held this lame leg off the ground or rested on the knee.

A ram about 6 years old, observed at East Fork on June 27, 1939, had a horn which, instead of curving outward, curved toward the neck so that in time, as it grew longer, it might gouge into the top of the neck.

On July 26, 1939, a lamb was noted at the head of East Fork River which had a seriously lame foreleg.

On Big Creek on August 16, 1939, Emmett Edwards saw a lamb with a severe limp in a foreleg. On August 18 he saw a ewe with a large raw spot on the right ham which appeared to be the result of a severe bruise.

On September 11, 1939, a lamb was seen on Polychrome Pass with a long deep gash across the rear of one ham. The hair around the wound was red from recent bleeding. The cut appeared to have been made by a rock. Possibly the lamb had fallen.

On September 12, 1939 on Igloo Creek, a lamb carried a crippled foreleg, not using it at all.

On September 20, 1939 I noted an occasional drop of blood in the tracks of some sheep which had been feeding in the snow. Nothing serious, but it indicates that the feet may be come quite sore in crusted snow.

On September 29, 1939, a yearling was seen with a decided limp in a foreleg. A ewe in the same band was soiled from the tail to the ankle. In the distance it appeared to be dried blood, but of this I could not be certain. It may have been due to diarrhea.

On June 8, 1940, a 2-year-old ewe was found dead at Igloo Creek on a low slope. A snag had penetrated the abdominal cavity and the small intestine.

Some years a go a ranger found a sheep at Igloo Creek which had died from a fall incurred by slipping on a glacier.

At least two instances of sheep frozen in overflow on the rivers have come to my attention.

In September 1928, five young rams were found dead in Savage Canyon. They had died from eating dynamite.

In the Park Superintendent's report for 1927 it is stated that a ranger found the carcass of a sheep at Toklat River. When found, the carcass was fresh and there were no marks on it except where birds had picked a hole in the entrails. The tracks in the snow showed that the animal had walked off some glare ice a distance of 25 yards and had dropped dead. The suggestion is made that is may have slipped on the ice and hurt itself internally.

THE MENACE OF DEEP SNOW

The deep snows of the winters of 1928—29 and 1931—32 took a heavy toll of the sheep. Apparently in some cases entire bands, in crossing from one mountain to another, became exhausted in the valleys and died en masse. There is no detailed report on the situation but it is stated that bunches of sheep were found dead with no indication that they had been killed by wolves. Some of the sheep were no doubt later fed upon by wolves and foxes, making it impossible so know whether the animals had starved or been killed. Many of the sheep killed by wolves during these two hard winters were no doubt first weakened by snow conditions. Perhaps most of these sheep were doomed, but it is possible that some of those killed by wolves might have survived the severe weather.

In April 1927. one of the rangers found a ram and ewe in a weakened condition in the deep snow as Sable Pass. The ewe was brought to Headquarters but died a few days later. The ram was found dead when the spot was again visited.

In February 1929, when the snow was unusually deep, two rams were seen to jump on a drift of loose snow and sink completely out of sight. In such a circumstance they would be quite helpless if a predator were near.

In April 1929, three ewes and three rams were rescued at Igloo Creek in a weak condition due to deep snows. One of the ewes was too far gone and died in a few days. After the sheep had been kept a while at Igloo and regained some strength they were taken to Headquarters. They were later moved to the University of Alaska where they were kept for several years.

Ranger John Rumohr stated that in the spring of 1932 when the snows were deep he had seen 30 old rams on the low banks bordering East Fork River south of the road. Later he found five of them dead, untouched by any animal.

The deep snows have played an important role in the control of the sheep population. Probably the larger the population the more drastically are the sheep affected. A large population quickly devours the food available on ridge tops and they must all go down to the deeper snow in search of food. A smaller number might find sufficient food on the ridge tops so pull them through a severe winter. This is an example of one of the regulatory devices of Nature.

Continued >>>

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