Ferruginous Pygmy-Owl Glaucidium brasilianum Scientific name definitions

This small owl is a permanent resident from the southwestern United States to southern South America, occurring in tropical, subtropical, and cold temperate lowlands (sea level to 1,400 m in the United States and Mexico; to 1,900 m in Central America). It occupies a wide variety of ecosystems, from semiarid desert scrub to lush tropical rain forest. Pairs typically nest in cavities excavated by woodpeckers, or those formed by limb decay, less often in forks or depressions in trees.

Ferruginous Pygmy-Owls are presumed monogamous, forming pairs during the fall of their first year after hatching, and nesting the following spring. Incubation and nestling development each last about 28 days. Females incubate 2–7 eggs, and both adults provide food for nestlings. Adults attend to fledglings until dispersal, 7–8 weeks after fledging.

An opportunistic predator, the Ferruginous Pygmy-Owl has a diet as diverse as its distribution, including insects, reptiles, amphibians, birds, and small mammals. Foraging rates peak during twilight hours, around sunrise and sunset. Because of its small size, long tail, and atypical diurnal and crepuscular behavior, the Ferruginous Pygmy-Owl may easily be mistaken for a passerine. When agitated, it perches with its tail cocked upward or jerks its tail up and down and from side to side.

From 1840 to 1991 this was the most collected species of owl in Mexico (Enríquez-Rocha et al. 1993 Enríquez-Rocha, P., J. L. Rangel-Salazar, and D. W. Holt (1993). Presence and distribution of Mexican owls: A review. Journal of Raptor Research 27(3):154–160. Close ), and it may be the most common small owl in lowland areas of the American Tropics (Oberholser 1974 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, Texas, USA. Close ). At the northern extreme of its range in Arizona, however, it is considered scarce and listed as Endangered, even though formerly common there in cottonwood-mesquite (Populus-Prosopis) woodlands and forests, nesting in Gila Woodpecker (Melanerpes uropygialis) and Gilded Flicker (Colaptes chrysoides) cavities.

Until recent studies in Texas (Proudfoot 1996 Proudfoot, G. A. (1996). Natural history of the Cactus Ferruginous Pygmy-Owl. Master's Thesis, Texas A&M Univ., Kingsville. Close , Proudfoot and Beasom 1996 Proudfoot, G. A. and S. L. Beasom. (1996). Responsiveness of Cactus Ferruginous Pygmy-Owls to broadcasted conspecific calls. Wildlife Society Bulletin 24:294-297. Close , Proudfoot and Radomski 1997 Proudfoot, G. A. and A. A. Radomski. (1997). Absence of hematozoa from Ferruginous Pygmy-Owls (Glaucidium brasilianum) in southern Texas. J. Helminthol. Soc. Wash. 64:154-156. Close , Proudfoot et al. 1998 Proudfoot, G. A., J. L. Mays, S. L. Beasom and R. Bingham. (1998). "Effectiveness of broadcast surveys in determining habitat use of Ferruginous Pygmy-Owls (Glaucidium brasilianum) in southern Texas." In Biology and conservation of owls of the northern hemisphere., edited by J. R. Duncan, D. H. Johnson and T. H. Nicholls, 338. St. Paul, MN: U.S. For. Serv. Gen. Tech. Rep. NC-190. N. Central Res. Station. Close ) and Arizona (Abbate et al. 1996 Abbate, D., A. Ditty, S. Richardson and R. Olding. (1996). Cactus Ferruginous Pygmy-Owl survey and nest monitoring in the Tucson Basin area, Arizona-1996. Phoenix, AZ: Arizona Game and Fish Dep. Close , W. Richardson pers. comm.), life-history information, especially breeding biology, was limited for this species. Current studies are addressing nest activity, nestling development, mortality, site fidelity, habitat requirements, and dispersal of young in Arizona and Texas.

To avoid reference redundancies, further information addressing research in Texas is by Proudfoot (GAP), unless other citations are given.