Glaucidium brasilianum - (Gmelin, 1788)
Ferruginous Pygmy-Owl
Other Common Names: Caburé-Ferrugem
Taxonomic Status: Accepted
Related ITIS Name(s): Glaucidium brasilianum (Gmelin, 1788) (TSN 177908)
French Common Names: Chevêchette brune
Spanish Common Names: Tecolote Bajeño, Caburé Chico
Unique Identifier: ELEMENT_GLOBAL.2.106384
Element Code: ABNSB08040
Informal Taxonomy: Animals, Vertebrates - Birds - Other Birds
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Aves Strigiformes Strigidae Glaucidium
Genus Size: C - Small genus (6-20 species)
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Concept Reference
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Concept Reference: American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Concept Reference Code: B98AOU01NAUS
Name Used in Concept Reference: Glaucidium brasilianum
Taxonomic Comments: We follow Sibley and Monroe (1990) in treating G. nanum and G. peruanum as distinct species. 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-Owl; Cuba and Isle of Pines).

Constitutes a superspecies with and has been considered conspecific with G. nanum (AOU 1998), which is treated here as a distinct species.
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 27Nov1996
Global Status Last Changed: 27Nov1996
Rounded Global Status: G5 - Secure
Reasons: Large range across Mexico, Central America, and South America; still common in much of range.
Nation: United States
National Status: N3 (05Jan1997)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Arizona (S1), Texas (S3B)

Other Statuses

IUCN Red List Category: LC - Least concern
Convention on International Trade in Endangered Species Protection Status (CITES): Appendix II

NatureServe Global Conservation Status Factors

Range Extent: 20,000-2,500,000 square km (about 8000-1,000,000 square miles)
Range Extent Comments: RESIDENT: south-central Arizona and southern Texas south through lowlands of Mexico, Central America, and South America to northern Chile, eastern Peru, Bolivia, central Argentina and Uruguay; also southern Chile and southern Argentina south to Tierra del Fuego, wintering north to northern Argentina (NANUM group). Elevational range: sea level to usually about 1200 m in western areas of Mexico, to at least 300 m in eastern areas; sea level to about 1850 m in Guatemala (Johnsgard 1988, Sibley and Monroe 1990).

Number of Occurrences: 81 to >300

Population Size Comments: Rangewide population unknown, but considered common throughout much of its range (Proudfoot and Johnson 2000). In Brooks, Kenedy, and Willacy counties, Texas, 1308 individuals estimated (Wauer et al. 1993); in Kenedy County, Texas, 745-1823 individuals estimated in 29,000 hectares of live oak-mesquite habitat (Mays 1996). In Arizona in 1999, 78 were detected in ten Arizona survey areas (Richardson et al. 2000); much appropriate habitat, however, has not been surveyed recently (Monson 1998, Richardson et al. 2000). May be more abundant in Mexico than previously believed, especially in the southern part of the range (USFWS 1994).

Overall Threat Impact Comments: Decline in the U.S. is due primarily to destruction and modification of riparian and thornscrub habitats via urban and agricultural encroachment, wood cutting, water diversion, channelization, livestock overgrazing, groundwater pumping, and hydrological changes resulting from various land-use practices (see USFWS 1994 for details); the same may be true in northern Mexico (Proudfoot and Johnson 2000).

Short-term Trend Comments: Rangewide trends unknown. Has declined significanty in the U.S. since 1900 (Millsap and Johnson 1988). Lack of good baseline data makes trend analysis difficult, however. Formerly common in appropriate habitat along lowland rivers of southern Arizona and in extreme southern Texas, now virtually extirpated in Arizona and limited to a very small area of Texas (Proudfoot and Johnson 2000). As much as 90% of its favored riparian breeding habitat in U.S. has been altered or destroyed (Johnson et al. 2000, Proudfoot et al. 2000, Proudfoot and Johnson 2000). Similar declines may have occurred in northern Mexico (Proudfoot and Johnson 2000).

Other NatureServe Conservation Status Information

Inventory Needs: Further, more extensive inventories needed to better establish trends at the northern end of its range (Texas, Arizona, and northern Mexico) (Cartron and Finch 2000).

Distribution
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Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) RESIDENT: south-central Arizona and southern Texas south through lowlands of Mexico, Central America, and South America to northern Chile, eastern Peru, Bolivia, central Argentina and Uruguay; also southern Chile and southern Argentina south to Tierra del Fuego, wintering north to northern Argentina (NANUM group). Elevational range: sea level to usually about 1200 m in western areas of Mexico, to at least 300 m in eastern areas; sea level to about 1850 m in Guatemala (Johnsgard 1988, Sibley and Monroe 1990).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
NOTE: The maps for birds represent the breeding status by state and province. In some jurisdictions, the subnational statuses for common species have not been assessed and the status is shown as not-assessed (SNR). In some jurisdictions, the subnational status refers to the status as a non-breeder; these errors will be corrected in future versions of these maps. A species is not shown in a jurisdiction if it is not known to breed in the jurisdiction or if it occurs only accidentally or casually in the jurisdiction. Thus, the species may occur in a jurisdiction as a seasonal non-breeding resident or as a migratory transient but this will not be indicated on these maps. See other maps on this web site that depict the Western Hemisphere ranges of these species at all seasons of the year.
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AZ, TX

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: NatureServe, 2002; WWF-US, 2000


U.S. Distribution by County Help
State County Name (FIPS Code)
AZ Maricopa (04013)*, Pima (04019), Pinal (04021), Santa Cruz (04023), Yuma (04027)*
TX Kenedy (48261)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
12 Central Laguna Madre (12110207)+
15 Middle Gila (15050100)+, Lower San Pedro (15050203)+, Upper Santa Cruz (15050301)+, Rillito (15050302)+, Lower Santa Cruz (15050303)+, Brawley Wash (15050304)+, Aguirre Valley (15050305)+, Lower Salt (15060106)+*, Lower Verde (15060203)+*, Lower Gila (15070201)+*, San Cristobal Wash (15070203)+, Rio Sonoyta (15080102)+, Tule Desert (15080103)+, Rio De La Concepcion (15080200)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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General Description: A small, long-tailed, yellow-eyed owl, with gray-brown upperparts; tail is reddish with dark or dusky bars; white underparts are streaked with reddish-brown; crown is faintly streaked; two white-margined black spots on nape resemble eyes (NGS 1983). From Mexico southward there is a grayish phase with white tail bands; in Arizona, the entirely rufous phase is less frequent than the grayish-brown phase (Johnsgard 1988). Female mass usually is 64-87 g (mean 75 g), male mass 46-74 g (mean 61 g) (see Johnsgard 1988).
Diagnostic Characteristics: Differs from northern pygmy-owl in having the breast streaks brownish instead of black, a streaked rather than spotted crown, and a rusty tail with dark bars instead of a dark brown tail with pale bars (Peterson 1990, NGS 1983). Long tail and lack of ear tufts distinguish this species from other small owls in North America.
Reproduction Comments: Egg dates: mainly May in Texas (eggs collected as early as late March); mainly April-May in Mexico; sometimes late March or June. In Texas, June eggs are probably replacement clutches (Proudfoot and Johnson 2000). In U.S. and Mexico, clutch size is 2-5, average 3.3 (n=43; Johnsgard 1988 in Proudfoot and Johnson 2000). In Texas, clutch size is 3-7, average 4.9 (n=58; Proudfoot and Johnson 2000). Incubation lasts about 21-28 days (Proudfoot and Johnson 2000), by female. Male sole provider until young are about 3 weeks old; young tended thereafter by both parents (Proudfoot and Johnson 2000); can fly at about 27-30 days. In Texas, hatching success from natural cavity nests was 77%, from nest boxes 72%; fledging success 70 and 78% respectively; nesting success 54 and 56% respectively. Natural cavities produced an average of 2.6 fledglings/nest; nest boxes produced an average of 2.8 (Proudfoot and Johnson 2000). Mortality of fledglings before dispersal was 37% in a Texas study (Proudfoot and Johnson 2000).
Ecology Comments: Occurs singly or in pairs, except when caring for dependent young. Young disperse 7 to 8 weeks after fledging; in Texas, birds banded as nestlings and relocated as nesting adults had dispersed 1.9 to 17.3 km (n=6) (Proudfoot and Johnson 2000). In Texas, mated males used about 1.3 to 23 hectares during the nesting season (n=9); one unmated male used 110 hectares during the same period. After fledging, families (n=5) used 9.3 to about 60 hectares until the young dispersed (Proudfoot and Johnson 2000). In Arizona, two pairs used 2 and 16 hectares during the nesting season (Proudfoot and Johnson 2000).
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Mobility and Migration Comments: At extreme southern end of range, may migrate northward for southern winter.
Palustrine Habitat(s): Riparian
Terrestrial Habitat(s): Desert, Forest - Hardwood, Savanna, Shrubland/chaparral, Woodland - Hardwood
Special Habitat Factors: Standing snag/hollow tree
Habitat Comments: In the tropics, inhabits many distinct lowland habitats: scrubby, arid open and semiopen woodland; riparian woodland; forest edge and transition to savanna; second growth; coffee plantations; scrubby pastures; thorn scrub; partially cleared lands; open situations with scattered trees and bushes; and suburban areas with large trees for nesting (AOU 1983, Stiles and Skutch 1989, Monroe 1968, Howell and Webb 1995, Ridgely 1976, Hilty and Brown 1986, Johnsgard 1988).

Arizona: at present mainly associated with Sonoran desertscrub, especially along washes with dense xeroriparian mesquite, palo verde, desert ironwood, desert hackberry, and catclaw acacia; in Tuscon area in low density residential areas dominated by saguaro and foothill palo verde, ironwood, and velvet mesquite, and augmented by irrigation and exotic vegetation. Formerly more common in riparian cottonwood-willow forests intermixed with mesquite bosques (Cartron et al. 2000).

Northwestern Mexico: Sonoran desertscrub, Sinaloan thornscrub, Sinaloan deciduous forest, riverbottom woodlands, cactus forest, and thornforest (see USFWS 1994).

Texas: Formerly common in coastal plain oak associations and Tamaulipan thornscrub of the lower Rio Grande valley region (mesquite, hackberry, oak, Texas ebony). Now the largest population is in coastal sand plains dominated by mixed live oak and honey mesquite forest (Wauer et al. 1993).

Northeastern Mexico: lowland thickets, thornscrub communities, riparian woodlands, and second-growth forest.

Nests usually in natural tree or columnar cactus cavity or abandoned woodpecker hole; reported sites 3.3-9 m above ground. Sometimes nests in termitary, well above ground (Costa Rica, Stiles and Skutch 1989); in hole in sand bank; or in tree fork or depression (Johnsgard 1988). May re-use old nest site. Has used fabricated nest boxes (Proudfoot et al. 2000).

Adult Food Habits: Carnivore, Invertivore
Immature Food Habits: Carnivore, Invertivore
Food Comments: Diet includes lizards, large insects, scorpions, small birds and mammals, and other small animals (Proudfoot and Beasom 1980, Cartron et al. 1999, Proudfoot and Johnson 2000). May attack animals as large as or larger than itself.
Adult Phenology: Circadian, Crepuscular, Diurnal
Immature Phenology: Circadian, Crepuscular, Diurnal
Phenology Comments: According to various sources: Chiefly diurnal; most active at dawn and dusk (NGS 1983). Active day or night (Hilty and Brown 1986). Largely crepuscular, but sometimes hunts in full daylight or on dark nights (Stiles and Skutch 1989).
Length: 17 centimeters
Weight: 75 grams
Economic Attributes Not yet assessed
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Management Summary
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Biological Research Needs: From Proudfoot and Johnson (2000):

1) Continue long-term life-history studies to establish viable recruitment standard for populations, and to use this standard to assess stability of populations in Arizona and Texas. 2) Ascertain limiting factors at northern limit of range. 3) Study the effect of habitat fragmentation on dispersal and gene flow. 4) Further taxonomic study, including studies on genetic variation among apparently isolated populations. 5) Study of diet across different regions.

Population/Occurrence Delineation
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Group Name: Small and Medium Owls

Use Class: Breeding
Subtype(s): Nest site
Minimum Criteria for an Occurrence: Evidence of historical breeding, or current and likely recurring breeding, at a given location, minimally a reliable observation of one or more breeding pairs in appropriate habitat. Be cautious about creating EOs for observations that may represent single breeding events outside the normal breeding distribution.
Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Separation distance is not intended to delineate demographically independent populations or metapopulations (such units would be quite large) but rather serves to circumscribe breeding occurrences that are of practical size for conservation/management use.

Separation distance is larger than three times the diameter of an average home range for these volant species; based the diameter of larger home ranges of males, e.g. those of Northern Pygmy-Owls given below.

Ferruginous Pygmy-Owl: post-fledging families used 9.3 to about 60 hectares until the young dispersed (Proudfoot and Johnson 2000).

Northern Pygmy-Owl: territory in Colorado estimated to be about 75 hectares (Rashid 1999, cited in Holt and Petersen 2000); home ranges of breeding males in Washington 170-230 hectares (A. Giese, pers. comm., cited in Holt and Petersen 2000); home ranges of males in Sweden averaged 231 hectares (Kullberg 1995).

Northern Saw-whet Owl: Two breeding males had home ranges of 142 and 159 hectares (Cannings 1987). Most breeding habitat probably supports a maximum of about 1 pair/square kilometer, often much less (Cannings 1993); singing males can be as close as about 250 meters apart (Swengel 1990).

Elf Owl: home ranges smaller, range 0.2-2.6, mean 1.0 hectares (Gamel 1997).

Flammulated Owl males had mean home ranges of about 14 hectares in Colorado (Linkhart 1984) and about 16 hectares in Oregon (during the incubation period; Goggans 1986). DNA data indicate very low differentiation among populations in different mountain ranges in New Mexico and Utah; evidently the species exhibits long-distance natal dispersal and frequent intermountain dispersal (Arsenault et al. 2005).

Whiskered Screech-Owls had home ranges about 1550 meters long, along permanent creek (Gehlbach and Gehlbach 2000).

Burrowing Owl: In Saskatchewan, the average home range was about 1.2 kilometers in diameter (Haug and Oliphant 1990).

Long-eared Owl: In Wyoming, breeding home range in riparian habitat varied from 34-106 hectares and averaged 51 hectares (Craighead and Craighead 1956).

Short-eared Owl: Breeding territories average 64 -74 hectares (Holt 1992, Clark 1975).

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .6 km
Inferred Minimum Extent Justification: Conservatively based on an average home range of 27 hectares for a Ferruginous Pygmy-Owl family (Proudfoot and Johnson 2000). A breeding male Northern Saw-whet Owl spent most of its active time in a core area of only 27 hectares (Cannings 1987).

Long-eared Owl: May use an IE of 0.8 km, which is the diameter of an average home range (Craighead and Craighead 1956).

Short-eared Owl: May use an IE of 0.9 km, which is based on an average breeding home range of 65 hectares.

Date: 26Feb2005
Author: Cannings, S., and G. Hammerson
Notes: Contains owls in the genera Otus, Glaucidium, Aegolius, Asio and Athene.

Use Class: Nonbreeding
Minimum Criteria for an Occurrence: Evidence of recurring presence of wintering individuals (including historical); and potential recurring presence at a given location. Occurrences should be locations where the species is resident for some time during the appropriate season; it is preferable to have observations documenting presence over at least 20 days annually. Be cautious about creating EOs for observations that may represent single events.
Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Separation distance larger than three times the diameter of an average home range for these volant species; based the diameter of larger home ranges of males, e.g. those of Northern Pygmy-Owls: in Washington 170-230 hectares (A. Giese, pers. comm., cited in Holt and Petersen 2000); in Sweden, averaged 231 hectares (Kullberg 1995).
Whiskered Screech-Owls had home ranges about 1550 meters long, along permanent creek (Gehlbach and Gehlbach 2000).

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .6 km
Inferred Minimum Extent Justification: Conservatively based on a home range of 27 hectares; for example, a breeding male Northern Saw-whet Owl spent most of its active time in a 27-hectare core area (Cannings 1987).
Date: 16Apr2002
Author: Cannings, S.

Use Class: Roost
Minimum Criteria for an Occurrence: Evidence of recurring, nonbreeding, communal roosting at a given location; reliable observation of multiple individuals roosting in a distinct habitat patch in multiple years. To avoid creating EOs for ephemeral situations, there should be evidence of communal roosting over at least two different (though not necessarily consecutive) nonbreeding seasons.
Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Separation distance is arbitrary. Pertinent biologically based separation criteria do not exist.
Date: 25Oct2012
Author: Hammerson, G.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 25Jan1995
Element Ecology & Life History Edition Date: 20Mar1997
Element Ecology & Life History Author(s): HAMMERSON, G., REVISED BY S. CANNINGS

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • U.S. Fish and Wildlife Service (USFWS). 1997. Determination of endangered status for the cactus ferruginous pygmy-owl in Arizona. Federal Register 62:10730-10747.

  • U.S. Fish and Wildlife Service (USFWS). 1998. Proposed determination of critical habitat for the Cactus Ferruginous Pygmy-Owl in Arizona. Federal Register 63:71820-71838.

  • U.S. Fish and Wildlife Service (USFWS). 1999. Designation of critical habitat for the Cactus Ferruginous Pygmy-owl (Glaucidium brasilianum cactorum). Federal Register 64:37419-37440.

  • Voous, K. H., and A. Cameron. 1989. Owls of the Northern Hemisphere. MIT Press, Cambridge, Massachusetts. 320 pp.

  • Zook, J. L. 2002. Distribution maps of the birds of Nicaragua, Costa Rica, and Panama. Unpublished.

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