PREY SELECTION AND FOOD-HABITS OF BURROWING OWLS IN COLORADO

Food habits of Burrowing Owls (Speotyto cunicularia) were studied duri ng the breeding seasons of 1990 and 1991 in central Colorado. Concurre nt insect availability studies were conducted to determine selection f or specific insect families. Analysis of 1445 castings indicated use o f only one insect family, the carrion beetles (Silphidae), at a rate g reater than expected based on availability in one year. Castings and p rey remains showed different dietary components. Prey remains showed g reater use of small mammals, moths, amphibians, and passerines, and ca stings indicated greater use of mice and beetles. Methodology in rapto r food habits studies may therefore bias results.