Fauna Series No. 5

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

CHAPTER TWO:
WOLF (continued)

Food Habits of Wolves

Data on the food habits of the wolves were acquired in different ways. Frequently wolves were observed chasing and killing their prey. Some carcasses on which they had fed were found, and when the snow was on the ground the tracks and signs in the snow recorded the story of their feeding activities. Data gathered by these methods were especially significant in considering the effect of food habits on prey species and have, for the most part, been discussed in those chapters dealing with the prey species.

The discussion of food habits in this section is primarily confined to the results obtained from the analysis of 1,174 wolf scats gathered on the sheep and caribou ranges. Field observations were extensive enough to give the general picture of the feeding habits of the wolves, but examination of the scat material brought out information not otherwise obtainable and placed the study on a quantitative basis. The data obtained from analysis of the scats supplement the other field observations on food habits.

Most of the scats contained the remains of only one food item. This is to be expected because so much of the prey consists of large animals which furnish food sufficient for a number of complete meals. When rodents were eaten, more than one food item was sometimes found in a scat. For instance, mice, ground squirrel, and caribou might all occur together. Except in the case of mice, usually only an individual of a species was present in a scat.

The scat data have been presented in Table 2, p. 53. The number of scats in which each food item was found have been tabulated and the data have been segregated according to the time and place that the scats were gathered. Those found from May 1 to September 30 have been designated summer scats. (The collecting of the 1941 summer scats was discontinued in early August.) Scats gathered from October 1 to April 30 during the 3 years represent the winter period. Those picked up at the dens were segregated since they were definitely dated and gave the feeding habits during the denning period. Since there were no significant differences in the contents between the scats of old and young wolves at the den, they were not segregated. Those gathered at the dens represent the feeding habits from early May to early July. When the wolves left the den, they moved only a short distance away, but sufficiently far to give another collection of dated scats. The locality used after leaving the den, which has been called the rendezvous, was occupied in the second week of July 1940, and most of July 1941.

While scats gathered at the dens and at the two rendezvous are closely dated, as are many of the others, there are a number of them which were deposited some time before they were collected. This is true of those containing adult Dall sheep remains in 1940, and especially in 1941. Most of those containing sheep remains were deposited during the winter and represent a winter rather than a summer food.

Some of the data in the table are misleading due to the manner in which the scats were collected. The 1939 scats indicate an unusually heavy predation on sheep the preceding winter. As a matter of fact, I believe that the predation during that winter was less than that in the following winter of 1939—40. The explanation for the large number of 1939 scats containing sheep lies in an analysis of my 1939 itinerary. That summer I spent much time searching for remains of sheep carcasses and skulls, so covered a great deal of the territory where wolves had fed on sheep. As a result, I found many scats at and near the carcasses and these naturally contained sheep remains. If there had been a similar concentration on this phase of the work in 1940 and 1941 no doubt many more scats containing sheep would have resulted, or if caribou carcasses had been visited the data would have been weighted with caribou records.

The data on food habits gained from the scats are closely correlated with the observed field conditions. In 1940, for instance calf caribou were plentiful near the wolf den and most of the scats at the den contained calf caribou remains. In 1941 calf caribou were readily available for most of the denning period, but their general absence from the den region for part of the period is reflected in a slightly higher frequency of marmot, ground squirrel, and mouse in the scats at the den. At the time the wolf families were occupying the rendezvous after leaving the den, both in 1940 and 1041, calf caribou were scarce within the hunting range of the wolves. This scarcity of calves is reflected in the reduction of calf remains and the noticeable increase in the incidence of ground squirrel and marmot, and in 1940, of mouse also.

One more correlation should be mentioned. In 1939, 33 scats contained lamb remains and of those gathered during the next 2 years only 9 contained lamb. The heavier predation on lambs in 1939 is correlated with the absence of calf caribou during the midst of the lambing period. In the absence of calves the wolves hunted sheep.

Big game (caribou, sheep, moose) was found in 935 scats, and other food items including rodents, birds, etc., were found in 415. These figures seem to represent fairly well the general pattern of the food habits of the wolves. Big game is the preferred food, but smaller animals are also utilized in varying degrees.

TABLE 2.— Classification of 1,350 individual food items found in 1,174 wolf scats collected in Mount McKinley National Park

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