Golden Eagle

How often do you see golden eagles in the area? Probably not too often as they are uncommon in southwestern Alaska. Still, they do occur here every year. Welcome to Bristol Bay Field Notes. I’m Rob MacDonald, a Wildlife Biologist with the Togiak National Wildlife Refuge.

Breeding populations of golden eagles here are migratory. They spend about five months between migration and breeding and then return to temperate latitudes thousands of miles to the south for the winter.

Golden eagle reproduction is linked to the abundance of their main prey: snowshoe hares, ptarmigan, ground squirrels, and marmots. When golden eagles arrive in the late winter, ground squirrels and marmots are still hibernating. So, their prey sources are limited to snowshoe hares and ptarmigan.

Golden eagles also have high energy demands during migration. This is right before their annual reproductive efforts, which also require high energy. This, coupled with the more limited prey base upon their arrival in Alaska, shows the important role snowshoe hares and ptarmigan play in the reproductive success of the golden eagles.

A study of golden eagles in Denali National Park by Carol McIntyre documented the significant correlation between the abundance of snowshoe hares and ptarmigan to the egg laying rates, average number of chicks per nest, and the overall population productivity of the golden eagles.

Of these productivity parameters, the rate of egg laying was the most important factor for the golden eagle population.

For Field Notes, I’m Rob MacDonald.