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Glaucidium brasilianumferruginous pygmy owl(Also: ferruginous pygmy-owl)

By Alison Rauss

Geographic Range

Ferruginous pygmy owls are non-migratory and are found in the southwestern United States, Central America, and South America. (Proudfoot and Johnson, 2000)

Habitat

Ferruginous pygmy-owls live in a variety of habitats throughout the Americas. They are found in cold temperate lowlands, subtropical, and tropical areas. They can be found in habitats ranging from deserts to rainforests. ("Whooo's Endangered?", 1998; "Sonoran Desert Conservation Plan", 2003; Proudfoot and Johnson, 2000; "Ferruginous Pygmy-Owl", 2003)

  • Range elevation
    1616 (high) m
    5301.84 (high) ft

Physical Description

Glaucidium brasilianum are very small and reach a size of only about 6 inches tall. They have round heads with black eyespots on the back, no ear tufts, and yellowish eyes. Adults often have white eyebrows, and white streaks on their heads. The body of the owl is reddish-brown in color with white streaks. The long tail is also reddish-brown. Their wings often have white streaks as well. The underparts are white. Males and females look very similiar to one another, but the females are slightly larger and more reddish in coloration. Juveniles look like adults, but their heads are often grayer and their eye spots lighter. Ferruginous pygmy-owls are similar to northern pygmy-owls, Glaucidium gnoma , but northern pygmy-owls are spotted rather than streaked, have whiter tails, and different vocalizations. ("Owling.com", 2003; Proudfoot and Johnson, 2000; "Ferruginous Pygmy-Owl", 2003)

  • Sexual Dimorphism
  • female larger
  • sexes colored or patterned differently
  • Range mass
    62.4 to 76.5 g
    2.20 to 2.70 oz
  • Range length
    16.5 to 18 cm
    6.50 to 7.09 in
  • Range wingspan
    37 to 41 cm
    14.57 to 16.14 in

Reproduction

Ferruginous pygmy-owls are monogamous, and usually form pairs in their first fall after hatching. (Proudfoot and Johnson, 2000)

Ferruginous pygmy-owls nest in natural cavities of trees, stumps, or cactuses (depending on what is available). The cavities that they nest in are often the made by woodpeckers (Piciformes). Males give territorial advancement calls (monotone whistles) to attract females and repel other males. Female respond with chitter calls, bending forward, and raising their tail 45 to 60 degrees in order to expose the vent and allow copulation. ("Sonoran Desert Conservation Plan", 2003; Proudfoot and Johnson, 2000)

  • Breeding interval
    Ferruginous pygmy-owls breed once a year. Eggs are layed in April or May.
  • Range eggs per season
    3 to 5
  • Average time to hatching
    28 days
  • Range fledging age
    27 to 30 days
  • Average time to independence
    8 weeks

Incubation usually lasts 23 to 28 days. Incubation of the eggs and brooding of the young is done by the females. Males are the providers of food for the first few weeks. They bring back food that the female tears up and feeds to the young. After about 3 weeks both parents go out to retreive food for their offspring. Young begin fledging between 21 and 29 days after hatching, and remain dependent on parents for about 8 weeks. (Proudfoot and Beasom, 1997; Proudfoot and Johnson, 2000)

  • Parental Investment
  • pre-hatching/birth
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
    • protecting

Lifespan/Longevity

There is little information to be found on the lifespan of ferruginous pygmy-owls.

Behavior

These owls are most active near dawn and dusk. They are either solitary or in pairs for mating purposes. In order to move within trees, they walk and hop from branch to branch. They also rapidly beat their wings in order to make short, direct flights. Ferruginous pygmy-owls perch in trees similarly to other owls, with their tails straight downward. Allopreening is done between paired adults, fledglings, and nestlings. ("Sonoran Desert Conservation Plan", 2003; Proudfoot and Johnson, 2000)

Home Range

Little to no information is available.

Communication and Perception

Ferruginous pygmy-owls can be heard calling more frequently around sunrise and sunset. Sounds that they make include whistled hoot and took noises, and high yelping twitters. Male calls are lower in tone than females. Males give territorial-advertisement calls and females vocalize through chitters. ("Sonoran Desert Conservation Plan", 2003; Proudfoot and Johnson, 2000)

Food Habits

Glaucidium brasilianum are opportunistic predators with diverse diets. They feed mostly on insects, but also on birds, reptiles, amphibians, and small mammals. They are diurnal and feed mostly during sunrise and sunset. In order to kill birds and some lizards the ferruginous pygmy-owl bites just behind their prey's head, while other lizards are swallowed whole. Insects are usually decapitated and only the soft body parts of them are eaten. Mammals are eaten piece by piece. Specific examples of what these owls feed on inlude grasshoppers and crickets(Orthoptera), scorpions (Arachnida), six lined race runners (Cnemidophorus sexlineanius), four-lined skinks (Plestiodon tetragrammus), and Texas spotted whiptails (Cnemidophorus gularis). (Proudfoot and Beasom, 1997; Proudfoot and Johnson, 2000)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • insects
  • terrestrial non-insect arthropods

Predation

In response to predators such as hawks, owls, snakes, and raccoons, ferruginous pygmy-owls either go into a vertical position and move their tail back and forth, or maintain an errect position with feathers close to their body. Nestlings sometimes spread out their wings and puff themselves up. (Proudfoot and Johnson, 2000)

Ecosystem Roles

These owls are predators of a variety of species that share the same habitat. (Proudfoot and Beasom, 1997)

Economic Importance for Humans: Positive

There are no known benefits that ferruginous pygmy-owls provide to humans.

Economic Importance for Humans: Negative

Because of their small population size, the land that these owls live on is protected from development and construction of new houses and buildings through the Endangered Species Act. (Jehl, March, 17 2003)

Conservation Status

Contributors

Matthew Wund (editor), University of Michigan-Ann Arbor.

Alison Rauss (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

US Forest Service Department of Agriculture. 1999. "CACTUS FERRUGINOUS PYGMY-OWL (Glaucidium brasilianum cactorum)" (On-line ). Accessed 03/19/03 at http://www.fs.fed.us/r3/coronado/grazing_bo/cfpo.htm.

Center for Biological Diversity. "Cactus Ferruginous Pygmy-owl (Glaucidium brasilianum cactorum)" (On-line ). Accessed 04/07/03 at http://www.biologicaldiversity.org/swcbd/species/pygmyowl/.

Rainforest Conservation Fund. 2003. "Ferruginous Pygmy-Owl" (On-line ). Accessed 04/07/03 at http://www.rainforestconservation.org/data_sheets/birds/pyg_owl.html.

2003. "Owling.com" (On-line ). Ferruginous Pygmy-Owl Biology. Accessed 03/19/03 at http://owling.com/Ferrug_nh.htm.

2003. "Sonoran Desert Conservation Plan" (On-line ). Cactus Ferruginous Pygmy-Owl. Accessed 03/19/03 at http://www.co.pima.az.us/cmo/sdcp/sdcp2/fsheets/po.html.

1998. Whooo's Endangered?. Environment, 40/10: 24. Accessed March 19, 2003 at http://proquest.umi.com/pqdweb?Did=000000036782249&Fmt=3&Deli=1&Mtd=1&Idx=8&Sid=5&RQT=309.

Jehl, D. March, 17 2003. Rare Arizona Owl (All 7 Inches of It) Is in Habitat Furor. New York Times.

Proudfoot, G., S. Beasom. 1997. Food habits of nesting Ferruginous Pygmy-Owls in southern Texas. The Wilson Bulletin, 109/4: 741-748. Accessed September 23, 2004 at http://proquest.umi.com/pqdweb?Did=000000026437471&Fmt=4&Deli=1&Mtd=1&Idx=6&Sid=1&RQT=309.

Proudfoot, G., R. Johnson. 2000. Ferruginous Pygmy-Owl. The Birds of North America, 498: 1-20.

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