There has been much debate over the classification of Glaucidium gnoma californicum. Some experts now believe that these G. gnoma californicum deserves specific status as G. californicum, but the taxonomy of the genus Glaucidium is controversial. Evidence used in support of their specific status include their vocalizations. Because owls in general are primarily nocturnal, or active at dusk and night, their physical appearance and plumage patterns are believed to be less important than their calls and songs (Heidrich et al. 1995). Glaucidium gnoma californicum, unlike other G. gnoma populations, primarily hunt during the day. Glaucidium gnoma resides on the west coast of North America (extending from Canada, down to Central America) (Holt 2000), Glaucidium gnoma californicum inhabits a more compact region on the west coast, through the Rocky Mountains - from southern Alaska to southern California (Owl Pages 2000).

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (200,000 to >2,500,000 square km (about 80,000 to >1,000,000 square miles)) This species is resident from southeast Alaska, portions of northern British Columbia, and southwestern Alberta south through the western United States, interior Mexico, and Guatemala to Honduras, and east to Colorado, central New Mexico, and western Texas; also in Cape district of Baja California Sur, Mexico (AOU 1998, Holt and Petersen 2000).

The Northern Pygmy Owl's most distinguishing feature is its "extra pair of eyes" found on the back of its head. These two black teardrop-shape markings, bordered by white, resemble eyes. The rest of this owl's head is, depending on its habitation, gray, red, or brown in color - covered on the surface by small white dots. Glaucidium californicum's light belly is accented by thick brown stripes running vertically down its chest (Owl Pages 2000).

The males and females are fairly similar in appearance. Their average wingspan is 38 cm. The female's average length, however, is slightly larger: 18.5 cm, compared to 16.5 cm in males. Though very small in size, the Northern Pygmy Owl's tail, which when sitting is held slightly cocked upwards, is comparatively long and is striped six or seven times by light-white stripes (Owl Pages 2000). Both male and female have large yellow eyes, a yellow hornbill, and grayish yellow-feathered legs and toes.

Though the Northern Pygmy Owl's plumage doesn't show any seasonal variation, their coat colors from the north to down south demonstrates considerable differences. In the northern regions, this bird's upper parts are much grayer than in the south where the bird's feathers are browner (Holt 2000). The juveniles are similar in color to their parents, but with fluffier unspotted plumage, and grayer heads (Owl Pages 2000).

Length: 17 cm

Weight: 73 grams

• Terrestrial

These owls inhabit open coniferous and mixed forests, but are not found in dense, continuous forests. This may have to do with the use of open spaces and clearings where they dive down at their prey. They also hunt in open fields, wetlands, logged areas, and the edge of meadows (Owl Pages 2000). Because they rely so heavily on old woodpecker cavities for their nests, this selection of habitation may not be solely due to their preferences, but focus around where these woodpeckers reside as well.

Glaucidium californicum prefers to roost in quiet, shady alder thickets (Owl Pages 2000).

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

Comments: Habitat consist of forests or open woodlands in foothills and mountains, including adjacent meadows while foraging (AOU 1983). Specific nesting habitat is variable across the large range; pure and mixed species coniferous forests, mixed coniferous-deciduous riparian forests, aspen stands in pine forests, and highland pine and cloud forests (Honduras) (Holt and Petersen 2000). Generally this owl does not occur in unbroken dense forest. Nests are in abandoned woodpecker holes and natural tree cavities in snags and larger living trees.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

In mountainous regions, individuals may move to lower elevations for winter (Campbell et al. 1990, Holt and Kline 1989).

In California and Arizona, linear territories were about 1.6 kilometers long (Marshall 1957, Noble 1990). In Oregon, singing males were separated by approximately 600 meters (D. Sater pers. comm., cited in Holt and Petersen 2000). In Colorado, territory estimated to be about 75 hectares (Rashid 1999, cited in Holt and Petersen 2000). Home ranges of breeding males in Washington were 170-230 hectares (A. Giese, pers. comm., cited in Holt and Petersen 2000). Home ranges of male Eurasian Pygmy-Owls in Sweden averaged 231 hectares (Kullberg 1995). Eurasian Pygmy-Owl have been reported to have breeding territories 50 to 400 hectares in size (Cramp 1985).

Unlike most owls that are active at night (Heidrich 1995) and rely mainly on sound or black-and-white vision, Glaucidium californicum hunts mainly by day. Therefore this bird relies mainly on its vision to capture its prey (Owl Pages 2000). Another notable difference between this owl compared to other owls is its noisy flight. Many owls have specially adapted feathers and wings for quiet flight. The Northern Pygmy Owl's wings not only make noise, but also whistle as it soars through the air (Holt 2000).

The Northern Pygmy Owl is a predominantly "sit and wait" type of predator. It sits and watches predominantly from the highest branches on trees (Owl Pages 2000) mainly for other birds, such as swallows, jays and chickadees, or sometimes mammals, such as shrews, moles and chipmunks (Holt 2000). When attacking its prey, it either dives down toward prey on the ground, or jump in a zigzag fashion from branch to branch before dropping onto its prey with its sharp claws (Holt 2000). These small owls, however, are much more vicious than they appear. They attack prey or run off predators that are up to several times their own size (Owl Pages 2000). After they catch a bird, they are plucked and either eaten entirely or only the brains are picked out (Owl Pages 2000).

Comments: This species is an opportunistic predator with a wide trophic niche; it feeds primarily on small birds, small mammals, insects, and reptiles. Stomach contents recorded from museum collections indicated that females ate significantly more small mammals than males did (Earhart and Johnson 1970). In Montana, mean body mass of vertebrate prey (birds and mammals) was about 38 grams, or 61% and 52% of male and female body mass respectively (Holt and Leroux 1996). Winter diet in Montana consisted of 36% birds (Holt and Leroux 1996). Northern pygmy-owls glides/dive down from an elevated perch to capture prey. Food items may be cached.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: This species is represented by a large number of occurrences (subpopulations).

10,000 - 1,000,000 individuals

Comments: Total adult population size is unknown but certainly exceeds 10,000. Rich et al. (2004) estimated population size at 100,000. Guesstimated number of breeding pairs in western Canada in the early 1990s was 2,000-10,000 (Kirk et al. 1995).

These owls tend to be solitary or in highly dispersed pairs or family groups throughout the year (Johnsgard 1988).

They are often mobbed, by a large number of bird species ranging from hummingbirds to jays--most of which are potential prey (Holt and Petersen 2000). Occasionally, mobbing individuals are attacked and killed (Holman 1926, R.J. Cannings pers. comm.).

Comments: Activity is chiefly diurnal; "hunts by day and into the evening" (Holt and Petersen 2000). Most vocalizations are at dawn and dusk (Noble 1990, Holt and Petersen 2000).

Glaucidium californicum breed from April to early June (Birds 2000). Though it is not known which sex is responsible for picking and building the nest, the actual sites are almost always old woodpecker cavities. The trees in which these birds nest are usually coniferous, and are found within boreal and deciduous forests. Glaucidium californicum have clutch sizes that range from 3 to 7, which the female incubates for about 29 days while the male is responsible for bringing back food to the nest. He also defends it from any predators. After the fledglings hatch, they grow quickly and reach almost adult size after 2 weeks. They fledge at approximately 30 days, but are defended and cared for by their parents for an extra 20 to 30 days (Owl Pages 2000).

Few nests have been studied. Egg dates: in North America from early April to mid-June; peak in late April to late May (Holt and Petersen 2000). Clutch size reportedly is 2-7 in North America (Holt and Petersen 2000); mean size reported to be 5 (n = 6, Bent 1938) and 3.7 (n = 10, Western Foundation of Vertebrate Zoology nest record cards). Incubation, by female, lasts probably about 28 days (Holt and Norton 1986); male brings food. After 9 days of age, young are fed by both parents, leave nest at about 23 days (Holt and Norton 1986).

Glaucidium californicum is currently not endangered or targeted by shooting and trapping. As with most forest-dwelling species, they are susceptible to habitat loss due to logging and burning of forests.

US Federal List: no special status

CITES: appendix ii

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N4 - Apparently Secure

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Still widespread in suitable habitat in western North America and portions of Middle America; no significant declines detected, but trends are poorly documented; adversely affected by logging practices that reduce nesting trees and impact foraging habitat.

Global Short Term Trend: Unknown

Comments: No rangewide information. Low abundance or dectability makes Breeding Bird Survey data unsuitable for determining trends. No significant trends indicated in Christmas Bird Count data (Sauer et al. 1996). Trend in Canada was reported as "?stable; little data available" by Kirk et al. (1995). There have been reports of local declines or extirpations following logging (Marshall 1988).

Global Long Term Trend: Unknown

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: This species may be threatened by certain logging practices that remove older trees and snags (Marshall 1988, Holt and Petersen 2000). Habitat changes (e.g., dense successional forests following logging) that reduce hunting habitat or populations of avian prey or primary nest excavators (woodpeckers) would also threaten this species (Holt and Petersen 2000).

Biological Research Needs: Little is known of the biology and ecology of this species. Research into phylogeny and taxonomy, population biology, migration, territoriality, nest site selection, pair bond, reproductive biology, and behavior needed (Holt and Petersen 2000).

Global Protection: Many to very many (13 to >40) occurrences appropriately protected and managed

Comments: Many occurrences are in protected areas.

Comments: Composed of three groups according to AOU (1998): californicum of U.S. and Canada; gnoma of Mexico, Guatemala, and Honduras; and hoskinsii of southern Baja California. Some consider hoskinsii to be a distinct species (Howell and Webb 1995, Robbins and Stiles 1999).

Relationships among New World Glaucidium taxa are not well understood (AOU 1983). Sibley and Monroe (1990) noted various differences among nominal taxa in morphology, vocalizations and ecological requirements and listed six New World species: G. californicum (Northern Pygmy-Owl, western North America; generally has been included in G. gnoma); G. gnoma (Mountain Pygmy-Owl, southwestern U.S. and northern and central Middle America; sometimes regarded as conspecific with Eurasian G. passerinum); G. minutissimum (Least Pygmy-Owl; Middle America and northwestern South America; two groups, minutissimum [Amazonian] and griseiceps [Least], probably are different species according to T. Schulenberg); G. brasilianum (Ferruginous Pygmy-Owl, southern Arizona through central South America; includes G. nanum, which consists of a greater percentage of dark morphs of G. brasilianum rather than constituing a distinct species; see Sibley and Monroe 1990); G. jardinii (Andean Pygmy-Owl, southern Central America and locally in western South America; may be an altitudinal race of G. brasilianum or more closely related to G. gnoma); and G. siju (Cuban Pygmy-Oowl; Cuba and Isle of Pines). Some of the information for the Northern Pygmy-Owl in Johnsgard (1988) pertains to the Eurasian species G. passerinum.