Modelling barred owl habitat in Northwestern Ontario

Abstract

With its large home range, dependence on large decadent trees for nest cavities, and association with mature mixedwoods, the Barred Owl (Strix varia) is vulnerable to habitat loss from forest harvesting. Study objectives were to document Barred Owl habitat associations and to determine whether habitat selection could be described in terms of land cover classes derived from satellite imagery. Owl locations were determined by call playback survey near Fort Frances, in Northwestern Ontario. Forest characteristics were measured on all selected and random non-selected sites. Regression analysis identified forest type, height and fragmentation as predictors of Barred Owl presence. Trembling aspen (Populus tremuloides), white birch (Betula papyrifera) , red pine (Pinus resinosa) or white pine (Pinus strobus) mixedwoods were selected. Owl presence probability increased with canopy height and the proportion forested in 280 ha around a site. A GIS-based habitat map, created from satellite image-derived land cover classes, distinguished good and poor habitat regions. A long-term, landscape-level approach is required to ensure a continuing supply of Barred Owl habitat in Northwestern Ontario's working forest. This study demonstrated that Barred Owl habitat can be characterized by forest data widely available in digital format, and thus is well suited to supply assessment and forecasting in a GIS (Geographical information Systern) .