Appearance

Xolmis are relatively large tyrant flycatchers of central and southern South America, and are primarily black, white, and gray. Fire-eyed Diucon has gray upperparts, with blacker wings. The tail also is gray, although the outer rectrices are paler. The throat is white, and the lower underparts are pale ashy gray. The species takes its English name from its bright red irides; the bill and tarsi are black. Sexes are similar in Fire-eyed Diucon; immatures are similar to adults, but have brown, not red, irides.

The generally gray plumage of Fire-eyed Diucon renders this species distinctive within its range in southern South America; at closer range, the red iris helps to clinch the identification. Ground-tyrants (Muscisaxicola) also are gray, but are more terrestrial, with longer tarsi; many species of ground-tyrant also have pale lores and supercilia, and a reddish or ochre crown patch, none of which are shared by the diucon. Common Diuca-Finch (Diuca diuca) is another mostly gray species that is widely sympatric with the diucon. The diuca-finch is smaller, with a shorter, stubbier bill, broad white tips to the outer rectrices, a gray breast band, and cinnamon flanks.

The following description is based on Smith and Vuilleumier (1971), Fjeldså and Krabbe (1990) and on Farnsworth and Langham (2004):

Adult: Upperparts and sides of the head dark gray. Primary coverts and remiges black; inner remiges edged with pale gray. The tips of the Rectrices pale gray, outer rectrices paler. Underparts generally pale ashy gray; throat paler, with faint gray streaks, and belly grayish white. Vent white. Sexes are similar in plumage, but in males the tips of the two outer primaries are strongly emarginated (see Figure 3 in Smith and Vuilleumier 1971: 189).

Juvenile: Little information; has "faint streaks on the breast and buffy coloration along the edges of [the] wing coverts" (Smith and Vuilleumier 1971: 195-196).

Undescribed.

Iris: bright red; brown in immatures

Bill: black

Tarsi and toes: black, blackish

Bare parts color data from Johnson (1967) and Humphrey et al. (1970).

Total length: 18.5 cm (Fjeldså and Krabbe 1990), 21 cm (Jaramillo 2003), 21-21.5 cm (Ridgely and Tudor, 1994)

Linear measurements (from Johnson 1967):

pyrope (n = ?)

male: wing length 110.3 ± 1.54 mm

         tail length 84.2 ± 0.73 mm

         bill length 14.5 ± 0.23 mm

female: wing length 103.9 ± 0.82 mm

         tail length 82.1 ± 1.00 mm

         bill length 15.4 ± 0.33 mm

fortis (n = ?)

male: wing length 114.5 ± 1.96 mm

         tail length 92.1 ± 1.40 mm

         bill length 16.9 ± 0.32 mm

female: wing length 111.5 ± 1.96 mm

         tail length 89.8 ± 1.50 mm

         bill length 17.7 ± 0.37 mm

Mass: mean 35.3 ± 3.2 g (range 31-42.4 g, n = 14, sexes combined?; Contreras 1975). "Two adult males each weighed 1 12/16 oz [49.6 g]; an immature male weighed 1 10/16 oz [46.2 g]" (Humphrey et al. 1970: 270).