Snowshoe Rabbit
Lepus americanus macfarlani
Like the ptarmigan and the northern weasel, the snowshoe rabbit, or varying hare, each autumn changes from a dominantly brown summer coat to a white winter ensemble. (In Washington where snow is scarce in its habitat, the snowshoe rabbit remains brown the year round.) His coat color blends at all seasons with his background, so all he need do to be fairly sure of escaping visual detection is to have confidence in his camouflage and sit motionless. The fur is so long, thick, and warm that he can sit all day in fifty below zero weather without freezing. His large hind legs are equipped with snowshoe feet, an obvious advantage in snow country.
The most favorable rabbit habitat is the brushy country along the east and north boundaries. Here a few may always be found. Out in the park they are quite scarce except in those years when the population is at or near a peak.
In winter, the rabbits feed on bark gnawed from various shrubs and saplings. Willow, dwarf birch and alder, because of their high palatability and abundance, are especially important winter foods. In years of rabbit abundance, I have seen patches of willow and dwarf birch trimmed to the snow line. At such times large willow brush may show a white band 2 feet wide where the rabbits have gnawed the bark within reach of the snow line. As the snow deepens, some foods are buried but the change of level brings new food supplies within reach. A variety of other shrubs are also eaten at this season. Spruce bark is relished. Porcupines, and also red squirrels, feeding in a spruce tree inadvertently add to the rabbit menu many dropped spruce twigs. In summer, the rabbits turn to a variety of fresh green foods.
The young of the snowshoe rabbit are furred and active when born and apparently there is no real nest provided. (In the cottontail branch of the family the young are born hairless, helpless and in a warm nest.) The litters may vary from one to six. The gestation period is about 36 days. The young are weaned (in captivity) when about 4 weeks old. The females breed again soon after a litter is born. It seems likely that a female may have as many as three or four litters during a summer. A male is apparently with a female for only a short time.
A number of animals are subject to cycles of extreme abundance and scarcity. The pendulum swings from one extreme to the other. A population, in spite of enemies of all kinds, increases until the numbers become so large that they threaten the food supply or, because of congestion, are drastically reduced by diseases. The length of cycle in a species depends upon annual losses and the rate of increase. Cycles are relatively short in voles and lemmings which breed at an early age (a few weeks), breed often, and have large litters. In these small rodents the cycle may cover a span of about 4 years. In larger species, the cycles are longer.
The snowshoe hare is one of the more obvious examples of a cyclic species. From acute scarcity the population in about 10 years pyramids until the country is full of rabbits. The woods are alive with a variety of activity. Enterprise, lovemaking, and tragedy are at their peak. Not only have the rabbits multiplied, but their enemies have flourished, and the lynx, fox, wolverine and birds of prey have all prospered, and certain enemies such as the lynx, become especially abundant.
During the high rabbit population peak, between 1953 and 1955, a few dead rabbits began to appear in the summer of 1954. In early August a group of tourists on a short walk noted three dead rabbits in the hotel area. But the rabbits were still numerous in the spring of 1955 and I anticipated the woods alive with young rabbits the following months. Instead, they decreased. By July, along Igloo Creek, they had become scarce. The so-called rabbit crash had taken place.
Nature steps into all situations, and one control or another automatically appears. Food shortage, disease, predation or competition enter the picture. Adjusting is a continuous process. Many people are talking and writing about the human population explosion in our midst, fearing that space for ourselves and nature is disappearing alarmingly. Perhaps we should consider the snowshoe rabbit.
