Hares play an important role in boreal forest ecology by forming the primary prey base for a number of predators including lynx, coyotes, goshawks, and great horned owls. Some of these predators are so dependent on hares for food that their populations change drastically in response to hare abundance, as does their foraging behavior. At the same time, hares have a considerable impact on shaping vegetation communities by selectively consuming willow and birch, which puts them in direct competition with moose.

A collared hare flees from its capture site in winter. Snowshoe hares can make 20 ft bounds and move as quickly as 40 mph in a bid to escape predation! (Photo by Amanda Foust)

As a prey item for so many predators throughout the year, snowshoe hares have a very low annual survival rate with 95% dying from predation. Consequently, hares are most commonly found in coniferous and shrubby habitats that offer concealment from predators. However, the best food items are sometimes found in riskier habitats. Is there a trade-off between cover and food? Are hares more susceptible to some predators than others in a given habitat? These are some of the focal questions of my study.

A collared hare is released in deciduous forest during its autumnal molt period. Changing color from brown to white is only one step towards avoiding predation. In the absence of leaves, even a well-camouflaged hare in motion is easily seen through the thin cover of bare tree stems. (Photo by Kara Dziwulksi)

In order to estimate survival rates and identify sources of predation, I collar snowshoe hares with VHF radio transmitters, which enables me to locate the animals when they die. After locating a dead hare, I search the area for tracks, scat, feathers, and hare remains that would indicate predation. Typically, a goshawk will pluck the fur from its catch, lynx and coyotes will consume everything except the feet and digestive organs, and horned owls will eat nearly every part of the hare. Occasionally, I find the collar at the top of a 100 ft spruce tree, buried in the side of a riverbank, or deposited in the underground maze of a red squirrel midden!

A common find in my study - digestive parts, stomach contents, an unlucky hare's foot, and the radio collar, all frozen into one giant mass. (Photo by Dash Feierabend)

My study focuses on the seasonal differences in survival of hares in black spruce and riparian deciduous forest, investigating the changes in avian and mammalian predation with the loss of deciduous leaves in fall and the accumulation of snow in winter. Deciduous forest may offer high quality food as well as cover from predators in the summer, but cover decreases significantly with the loss of leaves in winter. On the other hand, black spruce forest offers considerable cover year-round, with snow adding to available cover as it accumulates on the branches in winter.

A radio collared snowshoe hare, well suited to its environs. With the help of camouflage and a low footload, a hare can often evade a lynx in the deepest of snows. (Photo by Dash Feierabend)

One potential solution to maximize both browse quality and cover from predators is to move between habitats. Do hares move between drastically different habitats on a daily or weekly basis? Do females use different habitats for breeding than other times of the year? I am using collars equipped with GPS units for the first time on snowshoe hares to document the frequency of movement between deciduous and coniferous forests. With this data, we can also learn about a hare's daily activity patterns and home range size. Finally, we can record the paths taken during emigration events, the farthest of which has been nearly 9 miles!

Winter temperatures regularly dip below -30° F in interior Alaska, but this doesn't stop hares from moving in search of food. Using radio telemetry, I track a hare that has crossed the frozen Tanana River in mid-December. (Photo by Knut Kielland)