In the Pacific Northwest, they can quite adaptive to secondary forests. On the other hand, in Ontario where the barred owl is native, secondary forest seemed to be largely avoided per a study. In the recent western part of the range, barred owls often dwell in mixed wood areas, often where there are lowland stands of balsam poplar, trembling aspen and white spruce, occasionally but not commonly in pure conifer boreal stands. Barred owls in California preferred stands of red alder and appeared to avoid areas with higher densities of Douglas fir and tanoak. More so confined to inland areas, as in eastern Washington, Idaho, Manitoba and Montana, they prefer Douglas fir, ponderosa pine, paper birch, burr oak and western larch. In north-central Alberta, the use of old growth forest was far more prevalent than its occurrence in the wild. In the Cascades Range of Washington, barred owls usually dwell in areas with more grand firs, taller and more diverse tree heights, more enclosed canopies, higher numbers of trees per acre and less ground cover. In Saskatchewan, barred owls preferred areas with a minimum of 66% forest cover.