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Fauna Series No. 4






Population and Mortality







Other Larger Mammals

Small Mammals


Misc. Diet



Fauna of the National Parks — No. 4
Ecology of the Coyote in the Yellowstone
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IT IS DIFFICULT to determine the size of a coyote population, because seeing the animals is a matter of chance and estimating their numbers from tracks is uncertain due to their wide travels. It would be interesting to see what results could be obtained by judiciously distributing a number of elk carcasses over the range during a period of food shortage and then making a simultaneous count of coyotes visiting each carcass.

Skinner (1927, p. 186) placed the fall population of coyotes in the park at 400. He thought that the artificial control activities removed the yearly increase. It is my impression that 400 would represent the minimum number of coyotes in the park; how many more there might be is hard to estimate.

Since 1935, when control ceased, it is doubtful whether there has been any increase in the coyote population. Two park rangers interviewed felt that since coyote control was stopped the number of coyotes wintering in Pelican Meadows has remained about the same as when control was practiced. Three rangers and two park naturalists with whom the subject was discussed thought that there had been no increase of coyotes up to the spring of 1938. A man who ran a road grader almost daily between the Buffalo Ranch and Tower Falls in the summers of 1937 and 1938 said there seemed to be fewer coyotes in 1938 than in 1937. Others think that coyotes have increased since control was stopped.

In the winter of 1938—39 coyotes were generally reported scarcer at Mammoth. Some persons said that their howling had been seldom heard that winter. The apparent decrease of coyotes at Mammoth is balanced by an apparent increase in the Game Ranch area and in places adjacent to the park near Gardiner.

It was my impression that the coyote population in the spring of 1938 was no greater than in the spring of 1937. This was based on the number of coyotes seen in the field and the relative abundance of droppings along the trail. During a period of less than 2 weeks in February and March 1939 coyotes appeared to be fully as numerous as in 1938. The abundance of carrion in the winter of 1938 would lead one to expect a good increase in the coyote population that spring. Since artificial control in the park was stopped, the coyotes have become tamer and therefore more often seen. This fact must be kept in mind in estimating abundance of coyotes before and after artificial control.

In the absence of artificial control some fluctuations of coyote populations are to be expected, depending on food supply, condition of snow, and disease. It will be highly interesting to observe the effect of these natural factors. As pointed out elsewhere, natural controls are continuously operative and it is possible that at times they may operate more drastically than would artificial control.

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