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CALIFORNIA SPOTTED OWL
Strix
occidentalis occidentalis
The spotted
owl - the silent patriarch of old growth forests - has soared to
fame as the focus of several major conservation battles across
the West. In the early 1990s, the Northern spotted owl became
embroiled in controversy as unsustainable logging practices
collided with efforts to protect the owl's dwindling old-growth
habitat. Efforts to protect the owl's southwestern cousin - the
Mexican spotted owl - have also met with resistance. Both the
Northern spotted owl and the Mexican spotted owl are listed as
"endangered" under the federal Endangered Species Act.
The California spotted owl is
the lesser-known cousin of the Northern and Mexican spotted owl,
and is found in the Los Padres National Forest and other parts
of California. The California spotted owl - known as "CSO" for
short - is lighter brown in color and has larger white spots
compared to its northern counterpart.
According to the Forest
Service, "substantial threats" to the California spotted owl
exist throughout southern California. However, the CSO is the
only spotted owl
that has not
yet been placed on the endangered species list. In 2003 and
again in 2006, the U.S. Fish & Wildlife Service refused to place
the CSO on the endangered species list. As the owl awaits formal
protection, its population continues to decline across the
state.
 Habitat
California
spotted owls are
found
along the western slope of the Sierra Nevada, in the southern
Coast Ranges from Monterey County to Santa Barbara County, and
in the Traverse and Peninsular Ranges from southern California
to Baja California.
The owl
resides in forest habitats at elevations of below 1,000 feet
along the coast to as high as 8,500 feet inland.
California
spotted owls can be found in four general forest types in
Southern California: riparian-hardwood forest, live oak/big-cone
Douglas fir, mixed conifer forest, and redwood/California laurel
forest. They require a multi-layered forest habitat with high
canopy closure and a mixture of tree sizes and densities, as
well as large diameter old-growth trees for nesting and
roosting. CSOs are sensitive to high temperatures and during hot
summer days move up or down within the canopy to regulate their
body temperature.
California
spotted owls have large home ranges spanning from 1,000 acres to
nearly 9,000 acres. The Los Padres National Forest contains
approximately 144 spotted owl territories, including 30 in
southern Monterey County, 3 in the Cerro Alto area and 16 in the
southern Santa Lucia Mountains in San Luis Obispo County. In
Santa Barbara County, where spotted owl territories are more
plentiful, there are 12 in the Sierra Madre Range, 40 in the San
Rafael Mountains, and 18 in the Santa Ynez Mountains. In Ventura
County, 15 spotted owl territories occur around Mt. Pinos, 10 in
the San Emigdio Mountains, and 10 in the Cobblestone Mountain
area.
Reproduction
California
spotted owls are normally solitary creatures. They nest in
natural tree cavities, broken treetops, or abandoned nests of
other large birds in areas of dense old-growth forest. Spotted
owls breed between February and August, and have a single brood
of 1- 4 young per year. California spotted owlets (like the one
shown in the photo below) are pure white in color and develop
brown barring and overall color as they mature.
As is common
with most owl species, there is a strict division of parental
duties. The female owl incubates the eggs and, once they have
hatched, cares for the young. The male owl spends a large amount
of time foraging for food. The juveniles usually disperse from
the nest between September and October. Interestingly, the same
pair of breeding owls may use a specific nest site for 5-10
years before relocating, but they may not breed every year. The
survival rate of young spotted owls is extremely low, but when
they do survive to adulthood, they can live relatively long, up
to 17 years.
Behavior
California
spotted owls are nocturnal, sleeping during the day and active
at night. They are most active two hours after sunset and before
sunrise. In order to maintain comfortable body temperatures,
these owls tend to roost higher in the forest canopy during the
winter and lower in the summer. They will even switch roosting
location throughout the day in response to temperature changes
or exposure to direct sunlight!
California
spotted owls may begin foraging as early as an hour before
sunset. They are “perch and pounce” predators meaning they
generally find a suitable foraging site, select a single perch
and await prey to pounce on. They will rotate through several
foraging sites each night. Important prey for the California
spotted owl includes dusky footed woodrats, small mammals,
birds, and insects.
Threats
The
California spotted owl is listed as a Sensitive Species by the
U.S. Forest Service and by the California Department of Fish and
Game as a Species of Special Concern. Despite these
designations, the CSO continues to decline in southern
California due to stand-replacing wildfires, vegetation
management activities, salvage logging, urban development, and
several other uses and activities on the national forests.
Intense, stand-replacing wildfires are considered the primary
threat to California spotted owl habitat. Salvage logging, tree
mortality (such as that caused by sudden oak death), and drought
all pose threats to the species because they result in the loss
of large old growth trees which provide California spotted owl
habitat.
The recent
surge in vegetation clearing projects could have a substantial
effect on local CSO populations. The Forest Service estimates
that up to 25% of primary spotted owl habitat would be affected
by intensive fuel treatments, such as thinning, mastication, and
fuel break construction. ForestWatch monitors vegetation removal
projects on the Los Padres National Forest to ensure that any
treatments in these areas do not harm the spotted owl or its
habitat.
Because of
their specific habitat preferences, spotted owls in southern
California are very susceptible to fragmentation and populations
are usually clustered in disconnected “islands” of suitable
habitat surrounded by larger areas of unsuitable habitat. Human
activity within spotted owl habitat can not only lead to direct
habitat loss but also to noise disturbance, especially during
the nesting season.
California
spotted owls face competition from the invasive barred owl. This
aggressive relative of the spotted owl has increased in numbers
over the last decade and expanded its range further into spotted
owl habitat- muscling California spotted owls out of their own
territory.
ForestWatch is working to
strengthen the standards and guidelines in the Los Padres
National Forest plan to better protect California spotted owls
and their habitat.
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