BARRED OWL HABITAT USE AS DETERMINED BY RADIOTELEMETRY.

Abstract

Radio transmitters were successfully placed on 10 barred owls (Strix varia) during 1965-66, and the movement of the owls were followed with an automatic radio-tracking system for a total of 1,182 days. More than 28,000 owl locations were sampled from some two million locations recorded. These locations, along with habitat availability information, were programmed for computer analysis to determine intensity of habitat use. Barred owls showed consistent and highly significant preference or avoidance for different habitats despite changing seasons, phenology, weather conditions, and years. The order of habitat preference in decreasing intensity of use uZas oak ( Quercus pp. ) woods, mixed hardwoods and conifers, white cedar (Thufa occidentalis) swamps, oak-savannas, alder (Alnus spp.) swamps, marshes, and open fields. This paper reports the use of radiotelemetry to determine the intensity of use of various habitat types by barred owls. The recently accelerated interest in predatory animals and the difficulties involved in the study of generally nocturnal and little known avian predators presented a dual challenge to the technique of radio-track-