NATURAL HISTORY

MEXICAN SPOTTED OWL } Strix occidentalis lucida
FAMILY: Strigidae

DESCRIPTION: One of the largest owls in North America, with a wingspan of 45 inches, the Mexican spotted owl is a shy, chestnut-brown color with white and brown spots on its abdomen, back and head. Brown tails are marked with thin white bands.

HABITAT: Owls need western North American old-growth forests of white pine, Douglas fir, and ponderosa pine that create high, closed canopies, good for nesting. They nest in tree cavities, old bird-of-prey nests, caves, and potholes in cliff ledges.

RANGE: Mexican spotted owls have the largest geographic distribution of all spotted owl subspecies. It extends from the four-corner states southward into west Texas and Mexico’s Sierra Madres. But nearly 90 percent of known owl territories exist on Forest Service lands in Arizona and New Mexico.

MIGRATION: Mexican spotted owls appear to be largely nonmigratory, with some movement to lower elevations for winter. Some owls migrate 20 to 50 kilometers between summer and winter ranges.

BREEDING: Females lay one to four eggs (usually two) during early spring. Eggs are white and smooth, with a slightly grainy texture. The female sits on them and cares for the young, while the male provides food.

LIFE CYCLE: Most owlets leave the nest in June, about 35 days after hatching. Three weeks later, the young can use their talons to hold and tear prey on their own, but their parents continue to feed them until they become fully independent. Survival rate for the young is low, and lifespan is 16 to 17 years in the wild.

FEEDING: Mexican spotted owls feed on small mammals — wood rats, mice, voles, rabbits, pocket gophers, bats — as well as birds, reptiles, and insects. They hunt at night, moving from tree to tree, pausing to look and listen for prey, then pouncing.

THREATS: Logging, urban encroachment, mining, large-scale recreational developments and wildfire threaten the owl. Its distribution is shaped by the distribution of forest land that has been protected from destruction and logging: even-aged timber harvest systems that replace old growth spell lost habitat and starvation. Domestic livestock grazing has devastated the rare and invaluable riparian forests of the Southwest. Finally, great horned owl predation, low reproductive success, and low juvenile survival rates threaten this owl’s future.

POPULATION TREND: Like the other two subspecies of spotted owl, California and Northern, Strix occidentalis lucida has suffered extensive population declines. Only about 2,100 owls are thought to still exist north of the border, and far fewer in Mexico. The species has been extirpated from low-elevation riparian forests in Arizona and New Mexico. Between the years 1991 and 1997, research documented spotted-owl populations on the Gila and Coconino national forests declining by at least 10 percent per year. Scientists have continued to detect dwindling populations. Alarmingly, no owls successfully reproduced in the Gila study area in 2002.

Photo © Robin Silver