Reviewing some impressions of spring in Yellowstone there is an intermingling of emotions with certain events. This is a most critical season in the lives of our wild animals. It truly marks the passing of the old and the birth of the new.
As spring approaches, large herds of elk follow receding snow banks over time worn trails from their lower winter range toward the higher summer feeding grounds. Along these migration trails many animals fall by the wayside. Weakened by natural infirmities and old age, coupled with the rigors of a hard winter and limited winter range, their decaying bodies lend a discordant note to spring. Nature is consistent and ruthless in weeding out the unfit.
While on a two day trip from the Hellroaring Ranger Station, following down the slopes of the Yellowstone River, one hundred eight dead elk (Cervus canadensis canadensis) and thirteen deer (Odocoillus heminous macrotis) carcasses were counted by the writer and Dr. Adolph Murie on April 26 and 27. This number is not to be considered large in view of the many thousands of elk that follow this route. Most of the surviving animals at this time are rather scrawny in their ragged winter coats.
One month later the picture has changed. The animals, knee deep in grass and myriads of flowering plants, become sleek and shiny in their summer coats. At this time the bulls and cows range in separate scattered bands. When a lone cow is observed we know that she has a new born calf nearby or that she has left the band with which she has been ranging, to give birth to one. If we can watch the cow without being observed by her, generally she will point out the location of the calf. Otherwise it would be difficult to find.
There is a popular belief that elk, antelope and other wild mothers hide their young for several days in one spot until they are able to follow. Careful study of four newly born elk calves and two antelope kids shows that in neither case did the mother cache the young in a given spot. In each case observed, the young animals moved a considerable distance from where they were born and chose their own places of concealment. In one case a day old calf was observed to move twice in one hour without intervention on the part of the mother, a total distance of more than one hundred yards from the spot where it was born.
For a time after birth the elk calf is spotted and of a color that blends in quite perfectly with the background. It has often been said that while the calf is very young, its odor is not perceptible to any animal except its mother. This theory is not sound as there is evidence that predators occasionally find them chiefly by scent. Also their scent is definitely tangible at close range to human nostrils. It is definitely a pleasant, sweet, odor, entirely in keeping with the beauty of the young animal.
The heaviest natural losses in elk seem to be represented by infant mortality. It is estimated that not more than twelve or fifteen per cent of the total number of cows bring calves to the yearling stage. The total number of representative counts made by the writer this spring show only slightly over ten per cent yearlings.
It is recognized that some of the cows are barren, yet the mortality seems high. Evidence points to several causes. Undoubtedly many calves are born dead, or die shortly after being born. Some we know are premature, and still others are taken by predators. There are undoubtedly more important factors to be considered, chief among which is the toll exacted by hunters when the animals drift across the firing line to the north in the late fall and early winter. Of the calves observed to date, five dead have been seen, three of which were born dead or died shortly thereafter while the cause of death in the other two was not possible to determine.
The very young calves are excellent swimmers. One was observed to successfully follow its mother across the swollen waters of the Yellowstone River in Hayden Valley with ease; on the same day, June 6, a cow and calf were observed on the shore of Yellowstone Lake. Resenting photographers, the cow waded into the Lake and began swimming toward Stevenson Island, three and one-half miles away. The calf swam smoothly in its mother's wake for fifty yards until a motor boat headed her back to the shore.
The transition from winter to spring has been intensely interesting and our visitors have never had better opportunities of seeing large numbers of elk and other wild animals than is afforded at this time in all parts of the Park.
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