Laidig, K. J. and D. S. Dobkin. 1995. Spatial overlap and habitat associations of barred owls and great horned owls in southern New Jersey. Journal of Raptor Research 29:151-157. (Summary)
The barred owl (Strix varia), a threatened species in New Jersey, is closely associated with relatively undisturbed mature forests. In contrast, great horned owls (Bubo virginianus) are usually associated with highly fragmented landscapes of forests and fields. The two species are potential competitors where they co-occur. Great horned owls may also prey upon adult and juvenile barred owls. Barred owls have been extirpated from many areas of New Jersey but currently occur in substantial numbers in the extreme northwestern and southern portions of the state. We assessed the relative abundance, distribution, and habitat associations of both species in areas of known barred owl abundance in southern New Jersey by using taped playback of conspecific vocalizations. Estimated relative abundances of the two owls were virtually identical, and estimated home ranges overlapped extensively between the two species, although our data suggested that temporal partitioning may have reduced actual overlap. Barred owls were associated with cedar swamp-pitch pine lowland habitat. The area covered by mature hardwood swamps, considered optimal nesting habitat for barred owls, was limited and this habitat occurred only in small patches. We suggested that forest fragmentation is likely responsible for the high degree of spatial overlap found between the two species in southern New Jersey and poses a continuing threat to the integrity of the region’s barred owl population.