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Ferruginous Pygmy-Owl Glaucidium brasilianum

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

Systematics

Geographic Variation

Generally, northern populations appear to show somewhat longer wings and shorter tails (Proudfoot and Johnson 2000). Plumage coloration also shows some distributional variation: paler, more gray-toned plumage predominates in populations that occur in drier environments, while birds that live in moister environments typically display a brighter plumage (Proudfoot and Johnson 2000). The number of subspecies recognized varies from 12 (Dickinson 2003) up to 14 (Proudfoot and Johnson 2000):

ridgwayi: Range is central and south Mexico. Distinction between this subspecies and cactorum (see below) is slight.

cactorum: Range is south Arizona to Nayarit, Mexico. In comparison to ridgwayi, the wing is shorter, the tail longer, and the plumage paler and grayer.

intermedium: Range is Mexico from south Nayarit to south Oaxaca. Birds are paler than ridgwayi but darker than cactorum. Recognized by Proudfoot and Johnson (2000), but not by Peters (1940), Friedmann et al. (1950), Dickinson (2003), or König and Weick (2008).

saturatum: Pacific lowlands of Chiapas (District of Soconusco), Mexico, south into adjacent Guatemala. This subspecies is larger, darker above, and has more heavily streaked underparts than ridgwayi. Recognized by Proudfoot and Johnson (2000), but not by Peters (1940), Friedmann et al. (1950), Dickinson (2003), or König and Weick (2008).

medianum (north Colombia)

phaloenoides (north and east Venezuela, Trinidad, and Guianas)

margaritae (Venezuela)

duidae (Mt. Duida in south Venezuela)

olivaceum (Mt. Auyan-Tepuí, southeast Venezuela)

ucayalae (Amazon Basin from southeast Colombia, Venezuela, and Brazil to south Peru and north Bolivia)

brasilianum (northeast Brazil to northeast Argentina and north Uruguay)

pallens (east Bolivia, west Paraguay, and north Argentina)

tucumanum (northwest Argentina)

stranecki (central Argentina to south Uruguay)

Related Species

Until recently, the populations of Glaucidium in the lowlands of northwestern South America were classified as part of Glaucidium brasilianum brasilianum, which otherwise occurs only east of the Andes. These Pacific slope pygmy-owls now are recognized as a distinct species, Glaucidium peruanum (Peruvian Pygmy-Owl), primarily on the basis of different vocalizations (König 1991).

Questions remain regarding the species status of several other taxa in the brasilianum group. Proudfoot et al. (2006) proposed splitting Glaucidium brasilianum into two species based on mitochondrial DNA analysis and phylogeography. The researchers observed that populations in Arizona, Texas and Mexico are genetically distinct from populations in South America: they share no mitochondrial haplotypes, and have evidently no gene flow with South American populations (Proudfoot et al. 2006a; Proudfoot et al. 2006b). Similarly, Heidrich et al. (1995) and König and Wieck (2008) separate all North American taxa (south to northwestern Colombia) as Glaucidium ridgwayi (Ridgway's Pygmy-Owl), "on the basis of DNA evidence and vocalisations" König and Wieck (2008).

Subspecies tucumanum also has been recognized as a separate species (Heidrich et al. 1995); König and Weick (2008) include pallens in with tucumanum as well.

Most authorities (e.g. Peters 1940, Heidrich et al. 1995, Dickinson 2003, König and Weick 2008, Remsen et al. 2012) consider nana as a separate species (Austral Pygmy-Owl), but Marin et al. (1989) suggested that it may "merely represent a predominance of the darker rufous-brown morph" within brasilianum.

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