MEXICAN SPOTTED OWL HABITAT CHARACTERISTICS IN SOUTHWESTERN CHIHUAHUA, MEXICO

The Mexican spotted owl is listed as a threatened species in Mexico, b ut little is known there about its current status and habitat. Mexican spotted owls were surveyed by vocal imitations along transects on ste ep slopes, in canyons, and on lowlands and mesas from 20 May to 23 Sep tember 1992 and from 24 March to 26 July 1993 in southwestern Chihuahu a, Mexico. Transects encompassed 6,180 ha of forested habitat; 2,760 h a were on steep slopes, 2,960 ha were in canyons and 460 ha were on lo wlands and mesas. Twenty-five Mexican spotted owls were located among 13 localities. Habitats were characterized at seven roosting sites and one nesting sire. Four sites were classified as tree-roosting sites a nd three as cliff-roosting sites. Owls at tree-roosting sites were rec orded on NE- and NW-facing slopes at a mean elevation of 2,352 m, mean slope of 67.0% and mean canopy closure of 68.0%. Dominant species at tree-roosting sites were oaks, Ouercus spp. (48.5%), Arizona pine, Pin us arizonica (18.4%), Mexican white pine, Pinus ayacahuite (15.4%), an d Douglas fir, Pseudotsuga menziesii (11.6%),with mean tree density 64 3 trees/ha and mean tree basal area 28.5 m(2) ha(-1). Owls at cliff-ro osting sites were located on N- and NW-facing slopes at a mean elevati on of 2,413 m, mean slope of 76.3%, and mean canopy closure of 68.0%. Oaks (44.1%), Douglas fir (17.8%) and Mexican white pine (15.5%) were the dominant species at cliff-roosting sites, with mean tree density 6 10 trees/ha and mean tree basal area 30.7 m(2) ha(-1). Trees at the ne sting site were Mexican white pine (52.6%), aspen, Populus tremuloides (26.3%) and Arizona pine (21.1%).