Every 10 years or so, the hare population climbs to a peak and then crashes. It takes only two or three years for the cycle to bottom out before it starts climbing again.
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The last peak in Alaska was around 1999, and in recent years, the number of hares has been steadily increasing. The cycle is not synchronous throughout the state, but does follow the same general trend, with the peaks occurring a year or two earlier in the north and east. Snowshoe hare numbers appear to have peaked north of Fairbanks and in the eastern Interior in 2006, are now peaking in 2007 and 2008 in the western Interior and northern part of Southcentral. Hare densities are moderate in the Matanuska and Susitna Valleys and on the Kenai Peninsula and will likely continue to increase there through 2008.
Regardless of when the peak occurs, it's always followed by a rapid decline in numbers. The hare population crash is likely caused by a combination of factors including overbrowsing and starvation, predation and disease.
Predators kill a lot of hares during peak times, and hare production drops off with the dwindling food supply, leading to a rapid decline in the population. After two or three years, the food supply begins to build up again and the hare population begins to climb.
There is some variation to what's referred to as a 10 year cycle. Different factors may be involved, for example, a big fire might create good habitat five or 10 years down the road, spurring a population upswing.
Hares are important food for coyotes, foxes, golden eagles, owls, and especially lynx.
Lynx depend on snowshoe hares almost exclusively, which is why the lynx population mimics almost identically that of snowshoe hares. When hares are at a high, lynx are at a high. When hares crash, lynx crash.
Golden eagles in Interior Alaska also rely heavily on snowshoe hares when they return to Alaska in the spring. When there are a lot of hares, lots of eagles will attempt to nest. In years when there are very few hares, very few eagles will attempt to nest and lay eggs and very few young eagles are produced. The same is true for great horned owls.