Graphic Improvement Project

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Although some northern and California spotted owls select and avoid certain cover types, trends related to cover type or species composition are not consistent.[45]Mexican spotted owls apparently respond more consistently to cover type.[link widoczny dla zalogowanych] Roost sites in southern New Mexico occurred primarily in mixed-conifer forest, and owls selected mixed-conifer stands for roosting in all but 1 season/site combination [40]. Selection of mixed-conifer habitats was also observed in the Black Range and San Mateo Mountains of New Mexico and in the upper Gila Mountains region of Arizona [27]. In Arizona, the majority of foraging and roosting occurred in ponderosa pine-Gambel oak forests. Foraging and roosting stands in pine-oak areas also had generally higher Gambel oak density and basal areas than unused stands [24]. Similar trends have been observed in the Upper Gila Recovery Unit [24] and in the Black Range and San Mateo Mountains. Gambel oak's contribution to canopy cover, canopy layering, and prey habitat in mixed-conifer-hardwood and pine-oak communities likely influences its selection by Mexican spotted owls [24]. A review notes selection of white fir in the Basin and Range East region and several firs (Abies spp.) in Utah. There was significantly more Douglas-fir,[link widoczny dla zalogowanych] Gambel oak, and limber pine (Pinus flexilis) on roost sites than random sites in the upper Gila Mountains region [27]. Roosting Mexican spotted owls may have selected areas with greater southwestern white pine densities in southwestern New Mexico. Ponderosa pine and pinyon-juniper woodland were avoided by Mexican spotted owl in southern New Mexico [40]. Ponderosa pine was also more abundant in random stands than in nest stands in the Upper Gila Mountains and Basin and Range East recovery units.[27] In southern New Mexico, Mexican spotted owls had greater survival, increased fecundity,[link widoczny dla zalogowanych], and smaller home ranges in a mesic area dominated by mixed-conifer forest than in a xeric area dominated by ponderosa pine forests and Colorado pinyon-alligator juniper woodlands [40].
Northern spotted owls are strongly associated with multilayered forests. An uneven-aged, multiple-layered canopy is consistently included in descriptions of northern spotted owl habitat? [10][18][30][51]. Increased canopy layering was a significant predictor of northern spotted owl presence in Olympic National Park? [14]. In coniferous forests of northwestern Washington, the height class diversity, a measure of canopy layering, was significantly (P<0.1) greater in stands with more than 10% of telemetry locations compared to stands that were used less often? [15]. In coniferous forests on the eastern slope of the Cascade Range in Oregon and Washington, nest sites had more sapling, pole, and large trees, while unoccupied stands within 2,953 feet (900 m) of the nest site had more medium-sized trees. [link widoczny dla zalogowanych] This indicates a more layered canopy in occupied stands? [57]. However, the average number of canopy layers in small northern spotted owl nest plots was not significantly different from that on random sites within nest stands in the eastern Cascade Range of Washington? [46].