Three species of wild rabbits and hares are found in Pennsylvania: eastern cottontails, Appalachian cottontails and snowshoe hares. Domestic (or European) rabbits are not found in our area as a wild form; these are the familiar "Easter Bunny" seen in many pet stores and on the menu of some restaurants. European rabbits have been introduced, however, as a wild species into various parts of the world with serious negative consequences. In Australia, for instance, European rabbits have been blamed for the endangerment or extinction of some native kangaroos because of competition for food and habitat. By the way, what's the difference between the "Easter Bunny" and the Australian mattawho? You may ask, what's a mattawho? Nothing, what's the matter with you?

Everyone is familiar with eastern cottontails, which is a very adaptable species found in virtually all habitats from farmland to suburbia, including the Penn State campus. Although present today throughout the region, eastern cottontails historically had their share of conservation problems. Beginning in the mid-1920s, populations showed a rapid decline, which was blamed on intensive farming practices, which caused habitat loss, plus heavy hunting pressure. From the 1920s to the 1950s, wildlife agencies began major release programs to increase numbers throughout the eastern states. During these decades, as many as 50,000 eastern cottontails were released annually into Pennsylvania from several states. As a result of these introductions, the "new" eastern cottontail populations were no longer native and became very genetically variable, enabling these cottontails to adapt to changing habitat conditions and perhaps better compete with other cottontail species. Today, eastern cottontail populations are doing quite well, but large monoculture farms with little natural cover can seriously reduce population numbers.

Appalachian cottontails are physiologically better able to deal with winter conditions and exhibit less over-winter weight loss than eastern cottontails. This perhaps helps explain why Appalachian cottontails are better adapted to more northerly latitudes or at higher elevations than eastern cottontails. Incidentally, the Barrens (Scotia Range area of State Game Lands, 176 near campus) has a sizable population of Appalachian cottontails. But Appalachian cottontail populations have declined markedly in the past few decades, perhaps in response to expanding human population and conversion of younger (early successional) forests to older more mature forests throughout the Northeast. Similarly, snowshoe hare populations have declined in the Northeast during recent decades because of habitat loss, which consists of early successional forests.

Population cycles are an interesting phenomenon in hare populations. Cycles in snowshoe hares have been documented by scientists for about 150 years. In more northerly latitudes, like Alberta and Wisconsin, snowshoe hares undergo a "10-year-cycle," which actually may vary from 8 to 12 years, and population densities can vary 23-fold over the length of a cycle.

Snowshoe hare population cycles appear to be linked to winter food shortages when hares feed extensively on twigs and shoots of trees and other woody vegetation. As hare populations increase, food availability declines, causing population "crashes." Under these conditions, adult females produce fewer young. Precipitous drops in snowshoe hare numbers over the course of the cycle also can affect predator populations. For instance, the lynx, which is a well-known predator of snowshoe hares, initially may revert to other food items, e.g., carrion and ruffed grouse, as hares decline. Then lynx numbers may drop five-fold during years of low hare abundance compared to years with high abundance, and adult females may not produce kittens during hare scarcity.

In summary, the snowshoe hare cycle is a good example of how food availability can have profound effects on populations of both prey and predators. From a conservation perspective, eastern cottontails will continue to flourish, provided that early successional habitat is available. In contrast, conservation of Appalachian cottontails and snowshoe hares will require a concerted effort to ensure adequate habitat for these species in the face of increasing forest maturation and urbanization. While we are on the topic, here are two little-known rabbit facts: What's the best way to capture a rabbit or a hare? Hide behind a bush and make noise like a carrot. Also, speaking of carrots, how do you know they are good for your eyes? Did you ever see a rabbit with glasses?