Breeding Habitat of the Mexican Spotted Owl in the Tularosa Mountains, New Mexico

Abstract

We studied nest and roost habitat characteristics of Mexican Spotted Owls (Strix occidentalis lucida) in the Tularosa Mountains, New Mexico. Owls selected both nesting and roosting sites in mixed-conifer forests that contained an oak (Quercus sp.) component more frequently than expected by chance. With the exception of one cliff site, no owls were observed using piñon pine (Pinus edulis)/alligator juniper (Juniperus deppeana) woodlands for nesting or roosting. Owls selected nest and roost sites in forests characterized by mature (dbh > 45.5 cm) trees with high variation in tree heights and canopy closure >75%. Because we found little difference between nest microsites and their surrounding forest patches, the presence of a suitable nest structure may have determined nest-site selection within nest stands. Characteristics that best described nest sites in the Tularosa Mountains were also applicable to Mexican Spotted Owl nest sites in surrounding mountains. Seventy-five percent (n = 28) of nests were in Douglas-fir (Pseudotsuga menziesii), and 61% (n = 28) of nest structures were on clumps of limbs caused by dwarf mistletoe (Arceuthobium sp.) infections. Nest trees averaged 163.7 years of age (SD = 44.8) and 60.6 cm in diameter (SD = 22.4).