Ferruginous Pygmy-Owl Glaucidium brasilianum

  • Order: Strigiformes
  • Family: Strigidae
  • Polytypic: 13 subspecies
  • Authors: Ray Larsen


Conservation Status

According to the IUCN Red List of Threatened Species, the conservation status of the Ferruginous Pygmy-Owl is of Least Concern. The species has too large a range to be considered Vulnerable under the range size criterion, and too large a population size to be considered Vulnerable under the population size criterion. Although overall numbers are shrinking, particularly in north, the IUCN believes the rate is too slow to be classified as Vulnerable under the population trend criterion (BirdLife International 2009).

Effects of human activity on populations

The effects of human activity on the Ferruginous Pygmy-Owl is best known in Arizona, Texas and north Mexico where habitat loss, land conversion, urbanization, and the U.S.-Mexico border fence present obstacles to survivorship and gene flow. In the early half of the 20th century land was converted in these regions for grazing, woodcutting, and settlement, particularly in riparian areas (Johnson et al. 2003). The numerous damming projects on Arizona’s Salt River through the 1930s were particularly disruptive to the surrounding ecology (Johnson et al. 2003), and severely restructured once prime owl habitat. Although data is insufficient on historical and current population levels, it is widely acknowledged that Ferruginous Pygmy-Owls have become much more scarce in these areas, probably starting in the 1920s (Johnson et al. 2003; Proudfoot et al. 2006b). Flesch and Steidl also have discussed the U.S.-Mexico border fence as a threat to gene flow. In a 2010 study using 19 adult males and 54 juveniles, they calculated the mean flight height of local Ferruginous Pygmy-Owls at 1.4 m, and only 23% of flights exceeded 4 m (Flesch and Steidl 2010). The border fence, which is much higher, prevents the flow of individuals across the border, fragmenting the population and limiting gene flow. In addition, it interrupts the habitat and leads to edge effects (Flesch and Steidl 2010, Flesch et al. 2010). Ferruginous Pygmy-Owls are somewhat tolerant of human activities, however; current populations exist in the vicinity of villages and towns as large as Tucson, Arizona (Proudfoot and Johnson 2000). In 1997 the US Fish and Wildlife Service declared Glaucidium brasilianum Endangered in Arizona, and designated some protected areas of critical habitat for the species in 1998 (Proudfoot and Johnson 2000). Populations in north Mexico are similar to those in Arizona and Texas (Proudfoot et al. 2006a), but there the habitat has been less disturbed and populations are much more stable (Flesch and Steidl 2006).

Recommended Citation

Larsen, R. (2012). Ferruginous Pygmy-Owl (Glaucidium brasilianum), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.fepowl.01