Pygmy-owls (Glaucidium) are very small owls, with a large rounded head, a pair of prominent black marks (false "eye spots") on the nape, and a relatively long tail. Austral Pygmy-Owl is a relatively large species of Glaucidium, with a complex vocal repertoire. The upperparts usually are brown or gray, but less commonly are rufous; the underparts are white, marked with broad streaks that are the same color as the upperparts. The crown also has fine white streaks. Austral Pygmy-Owl overall is very similar to the brown and gray morphs of two related species, Peruvian Pygmy-Owl (Glaucidium peruanum) and Ferruginous Pygmy-Owl (Glaucidium brasilianum).
Austral Pygmy-Owl overall is very similar to the brown and gray morphs of two related species, Peruvian Pygmy-Owl (Glaucidium peruanum) and Ferruginous Pygmy-Owl (Glaucidium brasilianum). Austral Pygmy-Owl is mostly allopatric to both of these species. There may be some contact between Austral and Peruvian in northern Chile, however, at least during the nonbreeding season (Jaramillo 2003). Peruvian Pygmy-Owl is slightly smaller than Austral, with a shorter tail and shorter, more rounded wings; the tail of Peruvian has fewer whitish bars, and the bars do not meet along the shaft, as they do in Austral; and Peruvian often has narrow ochre band on the nape, bordering the lower edge of the black neck patch (this band is lacking on Austral) (Jaramillo 2003). The two species also have different songs. Austral Pygmy-Owl is similar in size to the southernmost populations of Ferruginous Pygmy-Owl, but is more boldly streaked below, and the tail is less barred (König and Weick 2008).
The following description is based on König and Weick (2008).
Adult: Sexes similar. Red and gray brown morphs are known, but in general Austral Pygmy-Owl is much less polymorphic than Ferruginous (Glaucidium brasilianum) or Peruvian (Glaucidium peruanum) pygmy-owls. Gray brown morph: Facial disc pale grayish brown with fine dark flecks and streaks; "eyebrows" and lores whitish. Upperparts dark grayish brown, spotted whitish (dots variable in size and shape). Forehead finely streaked whitish, crown with distinct, dense whitish to pale buff shaft-streaks. Feathers on either side of the midline of the nape are tipped black, forming an oval black spot ("false eye"), enclosed by white, on each side of the nape. Mantle and back irregularly spotted pale, outer webs of scapulars with large areas of white. Dark grayish brown flight feathers barred incompletely with rows of whitish or pale buffish spots. Rectrices dark gryish brown, with ca 8-11 very narrow buffish bars that reach shafts of rectrices; pale bars in general narrower than dark ones. Underparts off white with dark grayish brown, whitish speckled patches at sides of upper breast; white throat patch relatively small, continuing into narrow zone in center of belly, with further narrow white flank panel from about breast to thighs; area between central and flank panels densely marked with narrow and relatively short shaft-streaks and mottling light and dark. Tarsi feathered whitish, mottled with greyish-brown; toes bristled. Red morph: Similar in pattern to gray brown morph but dark grayish brown replaced by rufous brown (but never as foxy reddish as Peruvian or Ferruginous pygmy-owls). Intermediates between the two morphs also occur.
Down: Downy chick whitish.
Juvenile: Similar to adult but patterns less distinct, crown unspotted.
Iris: pale yellow; deep yellow, often with an orange tint, in immatures
Bill and cere: greenish yellow
Toes: yellow; claws dark horn with blackish tips
Bare parts color data from König and Weick (2008).
Total length: 17-21 cm (Jaramillo 2003, König and Weick 2008)
wing length: male, range 93-104 mm; female, range 97-108 mm
tail length: male, range 67-73 mm; female, range 68-76 mm
Mass: male 56-75 g, female 70-100 g
Linear measuments and mass from König and Weick (2008); for more detailed measurements see Jiménez and Jaksic (1989).