March 04, 2015
Weasel on the Menu
A new prey item was delivered to the nest, this time a weasel. Although there is much variation among sites, years, and seasons, the general picture of a Great Horned Owl’s diet across North America is relatively consistent; however, in Montana, Microtus voles constituted 92.6 percent of year-round prey, a remarkably higher percentage than in any other study. On average, biomass of mammals is by far the largest component; e.g. in their review of 22 studies across North America, Cromrich et al. (2002) noted that mammals constituted a minimum of 93 percent of the prey base in all studies; however many of these studies were biased towards methods such as analysis of pellets and prey remains that exaggerate the number of heavier-bodied prey items.