Habitat associations of Mexican Spotted Owl nest and roost sites in central Arizona

We analyzed landscape characteristics surrounding Mexican Spotted Owl (Strix occidentalis lucida) nest and roost trees in Arizona at three spatial scales: one circular plot of 201 ha (800-m radius) and two 400-m-wide "ring" plots between 800 m and 1,600 m from each nest or roost tree. The percentages of vegetation types were significantly different between 51 owl and 51 random areas only within the 201-ha circular plots. Owls selected both mature and young mixed conifer forests that had high canopy closure (≥55%) more than expected based on availability. Owls selected pine (Pinus spp.) and pine-oak (Quercus spp.) forests in proportion to availability. Forty-one percent of all nests and roosts were located in mixed conifer forests, even though this forest type covered only 5% of the study area. Pine and pine-oak forests covered 78% of the study area, and 59% of nests and roosts were located in these forest types. The only forest type in which we did not locate nests and roosts was mature open canopy ponderosa pine (P. ponderosa) forest. Owls occupied areas of predominantly younger forests, but only if residual large (≥45.7 cm dbh) trees were present. Indices of landscape structure did not differ significantly between owl and random areas. Future management of Mexican Spotted Owls in areas of moderate topographic relief should focus on retention of mature forests, especially mixed conifer stands with canopy closure ≥55%. Residual large trees, especially Gambel oaks (Q. gambelii), are important microhabitat components in younger forests.