The two species of Empidonomus are medium sized tyrant flycatchers with relatively long, slender bodies, a long tail, and relatively short tarsi. Adult Crowned Slaty Flycatcher is a browish gray above, with a black crown, a semi-concealed golden yellow coronal patch, a gray supercilium and dusky auriculars. The underparts are light gray, with a yellowish tinge on the belly. The bill and tarsi are black. Juvenile Crowned Slaty Flycatcher is similar, but has prominent but narrow white fringes to the wing coverts and inner remiges, the rectrices have narrow rufous fringes, and the supercilium is paler and more contrasting than in the adult.
Adult Crowned Slaty Flycatcher is unlikely to be confused with any other species; it is much larger than Slaty Elaenia (Elaenia strepera), which is more uniformly patterned and lacks the dark crown of Crowned Slaty. Juvenile Crowned Slaty Flycatcher is more similar to all plumages of Variegated Flycatcher (Empidonomus varius), but lacks the whitish submoustachial stripe and dusky lateral throat stripe of Variegated; the face of Crowned Slaty rarely, if ever, is as pale or whitish as on Variegated; Crowned Slaty has a plain breast (the breast of Variegated is streaked with dusky); and the back is more uniform, lacking the dusky mottling of Variegated (Schulenberg et al. 2008).
Information needed. Contribute
The migratory nominate subspecies molts on the wintering grounds. This molt is complete in adults; it is not yet known whether this molt also is complete in first year birds (Schulenberg et al. 2008).
Tarsi and toes: black
Bare parts color data from Wetmore (1926) and Belton (1985).
Total length: 16.5–18 cm (Schulenberg et al. 2010), 17.5-18 cm (Ridgely and Tudor 2009), 18 cm (Hilty 2003)
Mass: mean 35.2 g (range 27-46 g, n = 8, sexes combined?; Fiora 1934). Male, 27 g (n = 1; Belton 1985); female, 32 g (n = 1; Belton 1985).