Annual territory occupancy by Flammulated Owls (Otus flammeolus) in Colorado was evaluated from 1981-1996. Fourteen territories occurred within a 452 ha study area. Each year, three to six territories were occupied by breeding pairs and three to seven were occupied by unpaired males. Territories were occupied by breeding pairs a mean of 5.1 years (not necessarily consecutive) and by unpaired males a mean of 3.9 years (not necessarily consecutive). Territories most consistently occupied by breeding pairs contained the highest percentage of old (200-400 years) ponderosa pine/Douglas-fir, whereas territories least occupied by breeding pairs contained the least amount of this vegetation type.