Fauna Series No. 4

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

CHAPTER X:
SMALL MAMMALS IN RELATION TO COYOTES

SNOWSHOE HARE

Remains of snowshoe hare (Lepus bairdi bairdi) were found in 305 droppings, making up 3.44 percent of the items. Many of the hares had been eaten in winter while in the white pelage. Where hares are abundant, coyotes are able to hunt them systematically and subsist on them alone. Coyotes spending the winter in the interior of the park probably feed extensively on them.

The snowshoe hare is widely distributed but not abundant over most of the park. In a few places it seemed to be locally abundant; this was true in an area near Old Faithful. The sweeping cycles of abundance and scarcity do not seem to occur with any regularity in Yellowstone although there is, of course, some variation in numbers from year to year. In an old diary kept by the soldiers at Sylvan Pass in 1903, 15 or 20 hares were frequently reported seen in a day so that hares at that time must have been quite plentiful. Ranger Elliott (1931) reported hares more abundant at Yellowstone Lake than in several preceding years.

GOLDEN-MANTLED MARMOT

Remains of marmot (Marmota flaviventris nosophora) occurred in 120 droppings. The marmot is a natural coyote food and in some localities makes up an important part of the coyote diet. On the high ranges occupied by bighorn in Teton National Forest, where marmots are plentiful, they form the main item in the coyote diet. In Yellowstone, although marmots are plentiful in rocky areas, over large areas separating the typical marmot habitats they are scarce.

MUSKRAT

Remains of muskrat (Ondatra zibethica osoyoosensis) were found in 98 droppings. Muskrats are not very numerous but are generally distributed along the water courses and ponds. During the fall and spring they are especially vulnerable to coyote attack when they wander out over the snow. Should a muskrat be discovered by a coyote when journeying on land, its chance of escape, are, of course, slight. Journeys of more than 100 yards on the ice were noted. Once a fresh coyote track was seen which crossed the track of a wandering muskrat but, fortunately for the latter, they had not met. Coyotes have been found to investigate a network of tunnels along a stream hut it seems probable that muskrats are generally captured accidentally, for it would hardly be profitable for the coyote to spend a great deal of time hunting them. Coyote pressure on muskrats does not appear to be great.

GROUND SQUIRREL

Remains of ground squirrel (Citellus armatus) were found in only 46 droppings. The low incidence of ground squirrel in the diet is probably due to scarcity of these rodents over most of the park. It is possible that the ground squirrel population has been held in check by the coyotes. Ground squirrels make their appearance in the spring before the snow disappears, burrowing through the snow to reach the surface. Some ground squirrels appearing on the snow had traveled as far as 40 yards to feed on vegetation; at such times the ground squirrels would be highly vulnerable to predation. Tracks in the snow were noted several times showing that coyotes had chased ground squirrels.

On May 14, 1937, I saw a ground squirrel climb to the top of a sagebrush and peer after a coyote which had passed close to its hole, and this watchfulness was observed on two other occasions. Where the ground squirrel is plentiful on the coyote range it probably is an important food item.

Figure 50— Ground squirrel coming forth in early spring. This animal crossed 40 yards of snow to feed at the bare area.
At such times ground squirrels are especially exposed to coyote attack.
Jackson Hole, Wyoming, April 1937.

WHITE-TAILED JACKRABBIT

Remains of jackrabbit (Lepus townsendi campanius) were found in 37 droppings. This animal occurs only on the north side of the park and is not abundant, although tracks can always be found on its range. Since it does not occur in the interior of the park, there was no chance for it to be represented in about 3,500 of the droppings collected, so the incidence is lower than it would be if all the droppings were collected in jackrabbit habitat. George Bird Grinnell (Ludlow 1876), reporting on a trip made to the park in 1875, states: "Where all the coyotes and grey wolves have been killed or driven off, the hares exist in great numbers; but where the former are abundant the latter are seldom seen."

Because jackrabbits feed extensively on many plants, such as fringed sage brush and various kinds of yellowbrush, which are important big game plants, the coyote's predation on jackrabbits tends to be beneficial from the standpoint of preservation of the over-utilized range.

Figure 51— The jackrabbit is often an important food item in localities where it is abundant,
but in Yellowstone it is of minor importance.
Mammoth 1935.

PORCUPINE

Remains of porcupine (Erethizon e. epixanthum) were found in 35 droppings. Full-sized quills which became sharp on drying were frequently found in the droppings. Wherever porcupine occur they tend to appear regularly in the coyote diet. O. J. Murie (1935) found porcupine remains in 78 of 714 droppings gathered in Teton National Forest just south of Yellowstone Park. The observations of several men are given, showing that the coyote can kill a porcupine and probably does so frequently. Porcupine quills were found under the hides of many of the coyotes shot at the time that coyote control was practiced in the park. Near the South Entrance on March 19, 1937, Ranger Verde Watson (Yellowstone Nature Notes, March 1938, p. 15—16) found a porcupine that had been killed by two coyotes. They had worried it while it traveled to the river, where it had escaped, only to be again attacked and killed when it came to shore about 200 yards downstream. Now that other predators are rare in Yellowstone National Park the coyote probably serves as a useful check on the species.

DEER MOUSE

Remains of deer mouse (Peromyscus maniculatus osgoodi) were found in only 34 droppings. Considering the abundance of this mouse in the park, one would expect to find more of their remains in the droppings. O. J. Murie in his Jackson Hole coyote studies also found its incidence in the diet to be low, only eight deer mice occurring in 714 droppings and 64 stomachs. In some fox studies on the George Reserve in Michigan (Adolph Murie, 1934) I found that the deer mouse likewise made up but a small item in the fox diet. The deer mouse, although active above ground at night, is not so easily secured as the field mouse. It scurries from cover to cover, while the field mouse often feeds and travels in runways where it is easily captured by the coyote. It furnishes food for other animals equipped to feed readily upon it. Santee and Granfield (1939, p. 3—9) for instance, in California found the saw whet owl, Cryptoglaux acadica feeding almost entirely on the deer mouse, Peromyscus sp.

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