Strix occidentalis

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	STRIGIFORMES	STRIGIDAE

Scientific Name:

Strix occidentalis

Species Authority:

(Xantus De Vesey, 1860)

Common Name/s:

English	–	Spotted Owl
Spanish	–	Búho Manchado, Cárabo Californiano

Assessment Information [top]

Red List Category & Criteria:

Near Threatened ver 3.1

Year Published:

2008

Assessor/s:

BirdLife International

Reviewer/s:

Bird, J., Butchart, S.

Contributor/s:

Lammertink, M.

Justification:
This species has a moderately small population which continues to decline in northern and western parts of its range. As a result it is considered Near Threatened.

History:

2004

–

Near Threatened

Geographic Range [top]

Range Description:	Strix occidentalis has a population of c.15,000 individuals in four subspecies: caurina has a minimum of 3,778 pairs and 1,001 territorial individuals from south-west British Columbia, Canada, to north California, USA; the nominate has a minimum of 3,050 individuals in central and south California, USA, and (formerly) Baja California, Mexico; lucida has a minimum of 777-1,554 individuals from Utah and Colorado to Arizona, New Mexico and extreme west Texas, USA, and also occurs in Sonora, Chihuahua and Nuevo León to Jalisco, Durango, Michoacán and Guanajuanto, Mexico^1,3,4,5,8; and juanaphillipsae has been recently described from the State of México². Mexican populations may be stable because habitat tolerance is combined with forestry activities that typically modify rather than destroy habitat^5,6. Most other populations are declining and, in some, the decline is accelerating because of clear-felling and selective logging^3,7. The species is close to extinction in Canada.
Countries:	Native: Canada; Mexico; United States
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	Rich et al. (2004).
Population Trend:	Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	Most populations strongly associate with old-growth conifer or oak forests^3,4, but lucida also occurs in heavily logged secondary pine-oak forest, warmer and drier conditions and even bare rocky canyons^5,6. While some degree of logging may aid foraging, Spotted Owls associate with old trees and old-growth forest for nesting and roosting⁹. It occurs from sea-level to 1,200 m in the northern part of its range, and to 2,700 m in the southern part. Nests are generally in trees within closed-canopy forest, (usually in cavities or on stick platforms constructed originally by raptors, wood rats or squirrels), in caves, or on cliff-ledges in steep-walled canyons. Eggs are laid from March to May. Young and unpaired birds disperse, this adaptation has been shown to improve territory quality¹² and helps to sustain some sink populations. It feeds principally on nocturnal mammals.
Systems:	Terrestrial

Habitat and Ecology:

Most populations strongly associate with old-growth conifer or oak forests^3,4, but lucida also occurs in heavily logged secondary pine-oak forest, warmer and drier conditions and even bare rocky canyons^5,6. While some degree of logging may aid foraging, Spotted Owls associate with old trees and old-growth forest for nesting and roosting⁹. It occurs from sea-level to 1,200 m in the northern part of its range, and to 2,700 m in the southern part. Nests are generally in trees within closed-canopy forest, (usually in cavities or on stick platforms constructed originally by raptors, wood rats or squirrels), in caves, or on cliff-ledges in steep-walled canyons. Eggs are laid from March to May. Young and unpaired birds disperse, this adaptation has been shown to improve territory quality¹² and helps to sustain some sink populations. It feeds principally on nocturnal mammals.

Systems:

Terrestrial

Threats [top]

Major Threat(s):	Degradation and fragmentation of its habitat through clear felling and selective logging is the primary threat to the species. This has been compounded by the removal of a requirement that contractors assess the viability of wildlife on U.S. Department of Agriculture Forest Service lands¹⁰. It faces strong competition from Barred Owl Strix varia which is gradually displacing Spotted Owls from much of the northern part of their range, outcompeting it for food and space and occasionally hybridising¹¹. The extent to which Barred Owls have been responsible for recent continuing declines in Northern Spotted Owl populations remains uncertain.

Major Threat(s):

Degradation and fragmentation of its habitat through clear felling and selective logging is the primary threat to the species. This has been compounded by the removal of a requirement that contractors assess the viability of wildlife on U.S. Department of Agriculture Forest Service lands¹⁰. It faces strong competition from Barred Owl Strix varia which is gradually displacing Spotted Owls from much of the northern part of their range, outcompeting it for food and space and occasionally hybridising¹¹. The extent to which Barred Owls have been responsible for recent continuing declines in Northern Spotted Owl populations remains uncertain.

Conservation Actions [top]

Conservation Actions:	Conservation Actions Underway CITES Appendix II. The Northern (caurina) and Mexican (lucida) races are listed as Threatened under the U.S. Endangered Species Act. The Northwest Forest Plan was drawn up to provide protection and reduce rates of timber harvest leading to habitat destruction. Protected Activity Centres are advocated for as an effective mechanism of conserving the species in parts of its range¹³. Conservation Actions Proposed Large reserves, encompassing suitable habitat and widely distributed are needed to retain the owl's current range. Calls have been made for captive breeding of birds from the tiny remaining British Columbian population. To prevent local extinction a halt to logging operations is required in parts of its range. Research into the extent to which Barred Owls have precipitated recent declines in Spotted Owls is required. Continue monitoring population trends.

Conservation Actions:

Conservation Actions Underway
CITES Appendix II. The Northern (caurina) and Mexican (lucida) races are listed as Threatened under the U.S. Endangered Species Act. The Northwest Forest Plan was drawn up to provide protection and reduce rates of timber harvest leading to habitat destruction. Protected Activity Centres are advocated for as an effective mechanism of conserving the species in parts of its range¹³.

Conservation Actions Proposed
Large reserves, encompassing suitable habitat and widely distributed are needed to retain the owl's current range. Calls have been made for captive breeding of birds from the tiny remaining British Columbian population. To prevent local extinction a halt to logging operations is required in parts of its range. Research into the extent to which Barred Owls have precipitated recent declines in Spotted Owls is required. Continue monitoring population trends.

Citation:	BirdLife International 2008. Strix occidentalis. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 21 May 2012.
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