The Mexican spotted owl occurs in forested mountains and canyonlands throughout the southwestern U.S. and Mexico. It ranges from Utah, Colorado, Arizona, New Mexico and the western portions of Texas south into several states of Mexico. Whereas this owl occupies a broad geographic area, it does not occur uniformly throughout its range. Instead, the spotted owl occurs in disjunct areas that correspond with isolated mountain ranges and canyon systems.
In 1993, the U.S. Fish and Wildlife Service listed the Mexican spotted owl as threatened under the Endangered Species Act and in later in 2004, the agency designated critical habitat for the owl. One of the primary reasons for the original listing of the Mexican spotted owl in 1993 was the historical alteration of the owl's habitat as the result of timber-management practices. The other primary reason for listing this species is the threat that these practices continue to have on the species, as evidenced in existing national forest plans. At the time of listing, we also recognized the danger of stand-replacing wildland fire as a threat. Currently, the primary threat to the Mexican spotted owl in the U.S. is the increased risk of landscape scale stand-replacing wildland fire.
The Mexican spotted owl has a mottled appearance with irregular white and brown spots on its otherwise brown abdomen, back and head. Spotted owls have dark eyes in contrast to other medium to large North American owls that have lighter colored irises. Both remiges, or wing feathers, and retrices, or tail feathers, are dark brown barred with lighter brown and white. The retrices of adults that are more than 27 months old have rounded tips, and the terminal band is mottled brown and white.
Adult male and female spotted owls have similar plumage, but there are plumage differences in juvenile and subadult spotted owls. Juvenile spotted owls, from hatching to approximately 5 months, have a downy appearance that persists around the head even after the flight feathers grow in. That said, as late August or September of their hatch year you may spot that downy look. Subadults, 5 to 26 months old, closely resemble adult plumage, but they have pointed retrices with a pure white terminal. The owls molt their tail feathers at about 27 months of age.
The spotted owl has a wide repertoire of calls, most of which are relatively low in pitch and composed of pure tones that allows the owl to conduct long-distance communication through dense vegetation. This likely is important in a nocturnally active animal that ranges over large areas and that needs to communicate effectively with both its mate and neighboring owls across large distances. We can distinguish male and female spotted owls by their calls. Males have a deeper voice than females and generally call more often than females.
The Mexican spotted owl ranks as one of the largest owls of North America's 19 species. Only four are larger. The spotted owl does not have external ear tufts, and the head has a rounded appearance. The large round facial disk has indistinct concentric circles around both eyes.
Length: 41 to 48 cm (16 to 19 inches)
Wingspan: 107 to 114 cm (42 to 45 inches)
Like many other raptors, Mexican spotted owls exhibit reversed sexual dimorphism, where females are larger than males. On average, females are 100 grams (3.5 ounces) heavier.
Weight: 547 to 647 grams (19.5 to 23 ounces)
Outside of their breeding season, Mexican spotted owls are generally solitary. Their home ranges vary from roughly 3,700 acres (few hundred hectares to 1,500 hectares). Some may migrate 20 to 50 kilometers (12.5 to 31 miles) between breeding seasons, from March 1 through August 31, and their winter seasons. Mexican spotted owls also may migrate vertically from high elevations to lower elevations in winter, and tend to exhibit high fidelity to their home ranges.
Juveniles leave their natal territory in September. These dispersing juveniles can occur in a variety of habitats that range from high-elevation forests to pinyon-juniper woodlands, as well asareas that are surrounded by desert grasslands. Through the first winter, juvenile owls will travel through a variety of vegetation communities, remaining in one area for several weeks before moving on. Juvenile survival is very low, with few juveniles surviving their first winter or establishing a territory.
The average actual life expectancy for Mexican spotted owls in the wild is about 15 years.
Mexican spotted owls have one mate at a time and generally form long-term bonds with their mates. The reproductive sequence of events varies somewhat across their range, but courtship typically begins in late-February to March and the female may lay two to four eggs in late March to early April. The female spotted owl is solely responsible for incubating the eggs, which typically lasts 30 days. The male owls do most or all of the foraging for food during this time. The eggs hatch in early May, and the nestling owls usually fledge four to five weeks later. The young owls are dependent upon their parents for food through the summer and eventually disperse from the natal area in fall.
Mexican spotted owls nest and roost primarily in closed-canopy forests or rocky canyons. In the northern portion of the range, in southern Utah, Colorado and parts of northern Arizona and northern New Mexico and extreme southeastern portions of the range, most nests are in caves or on cliff ledges in steep-walled canyons. Elsewhere, the majority of nests appear to be in trees, but cliffs and caves can be locally important. Mexican spotted owls do not build nests, opting instead to use existing structures like dwarf-mistletoe induced witches’ brooms in trees or caves on rock faces.
The availability of habitat used for nesting and or roosting by Mexican spotted owls limits their distribution in forested and rocky-canyon environments. In the northern part of their range - far northern Arizona and New Mexico and southern Utah and Colorado - Mexican spotted owls use rocky canyons, outside of these areas, spotted owl use forested mountains and canyons. Mexican spotted owl most often use mixed conifer forest for nesting and roosting, but also use Madrean pine-oak forests, throughout the range.
Nesting habitat is typically in areas with complex forestor rocky canyons. These areas contain mature or old growth stands which are uneven-aged, multistoried and have high canopy closure. In the northern portion of the range, in southern Utah and Colorado, most nests are in caves or on cliff ledges in steep-walled canyons. In forested areas, the majority of nests are in Douglas-fir trees, typically in dwarf-mistletoe induced witches’ brooms.
The patterns of habitat use by foraging owls are not well known, but Mexican spotted owls generally forage in a broader array of habitats than they use for nesting and or roosting.
Land covered by evergreen trees in cool, northern latitudes. Also called taiga.
Mexican spotted owls forage primarily at night, starting at sunset and continuing until just before sunrise. They feed on small mammals, particularly mice, voles and woodrats, but will eat small birds, bats, reptiles and arthropods.
Mexican spotted owls generally perch and detect prey by sight or sound. After they detect prey, they pounce, capturing it with their talons. They also can take prey on the wing, particularly birds.
Mexican spotted owls roost during the day and hunt at dusk and at night. They may leave the roost during day to capture prey beneath their roost, retrieve cached prey or to drink or bathe in a stream.
Mexican spotted owls call mainly from March to November and are relatively silent from December to February. Calling activity increases from March through May, although nesting females are largely silent during April and early May. Come June through November, calling declines. Calling activity is typically greatest during the two-hour period following sunset and just before sunrise.
The Mexican spotted owl is one of three subspecies of spotted owl recognized by the American Ornithologists’ Union. The other two subspecies are the northern and the California spotted owls. The Mexican subspecies is geographically and genetically isolated from both the California and northern subspecies.
Two other species within the genus Strix occur north of Mexico, the great gray and barred owls. The great gray owl is a northern species that does not occur within the range of the Mexican spotted owl. Historically, barred owls did not occupy the same geographical range as Mexican spotted owls within the United States. However, we have reports of unconfirmed sightings of both species from the vicinity of Big Bend National Park in southern Texas in recent times, and there are recent confirmed records of barred owls in northern and eastern New Mexico. Whether these confirmed records indicate a range expansion by barred owls or vagrancy is unknown.
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