Amanda Kistler

Document Type

Honors Project

First Advisor

Dr. Michael Hensley

Degree Award Date

Fall 2008


Determination, Statistical Comparison, diet, Barn Owls, Northwestern United States, Shenandoah Valley


Animal Sciences | Poultry or Avian Science


The Barn Owl, Tyto alba, is a medium sized nocturnal owl being North America's only member of the family Tytonidae, also known as the monkey-faced owl family. Fitting this description, North American Barn Owl's possess a distinctive heart shaped facial disk ranging in color from white with brown to orange colored borders with females possessing slightly darker colors than males. Other relatively distinct qualities of Barn Owls are their long legs, only surpassed by the Burrowing Owl, and relatively small eyes in comparison to other nocturnal owls. Specifically Barn Owls prefer living in open low-lying areas with high populations of small mammals, specifically voles. Also important is the Barn Owl's preference for areas of milder climates with old buildings or hollow trees for perching and nesting while avoiding areas with harsh winter temperatures, densely forested, and overly cultivated areas. Still, despite the similarity in niche preference, the diets of Barn Owls have the capacity to diverge significantly depending upon the specific region and food availability in the chosen niche. According to the article, Summary of California Studies Analyzing the Diet of Barn Owls by Chuck Ingels, prey was analyzed at seven locations in and around California to establish the percent composition that each prey comprised in the Barn Owl's diet. Based on this method, it was determined that the California meadow vole, Microtus californicus, was the most prevalent prey comprising about thirty-one percent of the Barn Owl diet. Other common prey were the Pocket Gopher, Thomomys bottae, comprising eighteen percent of the owl's diet and the White-footed mouse, Peromyscus, comprising fourteen percent of the Barn Owl's diet. Supporting this information, the World Owl Trust claims that voles comprise of over fifty percent of Barn Owl's diet, mice comprising about fifteen percent, shrews comprising almost thirty percent, and birds and other small mammals comprising the last five percent of the owl's diet.

Due to this possible variation in diet, a study will be conducted determining the percent composition of the Barn Owl diet in the northwestern United States which will then be statistically compared to data collected from Barn Owls from the Shenandoah Valley using the same dissection and identification methods. The method of collection and identification will be similar to that exhibited in the article Common Barn Owl Diet in Northeastern Utah where the pellets will be collected, dissected, and identified using skeletal keys . Initially about twenty pellets will be obtained from a Barn Owl population in the northwestern United States and dissected looking specifically for animal remains. Then, using skeletal keys and focusing specifically on the skulls, the remains will be identified. Once the identification process is complete, the percent composition of the Barn Owl's diet will be determined. Following the determination of the contents of the northwestern United States pellets, a statistical comparison will be made with data collected from pellets of Barn Owls from the Shenandoah Valley.