One of the Amazonian Motmot's most distinctive features is the cap of dark blue feathers stretching from the base of the beak to the back of the head, with a small patch of black on the top part of the crown. The blue component of the cap does not extend below the eyes, which are masked with a triangle shaped wedge of black feathers. The rest of the body is green on the back and wings, lighter green to tawny on the underparts. The throat is bluish-green. The Amazonian Motmot also has a long tail with a "racquet" tip.
The Amazonian Motmot is the only member of the "Blue-crowned Motmot" complex that occurs in Amazonia, and so readily is identifiable within its geographic range. The Andean Motmot (M. aequatorialis) is similar to the Amazonian Motmot, and replaces it at higher elevations in the Andes from Colombia south to Bolivia. The Andean Motmot is larger than Amazonian, and is greener on the underparts, with little if any of the tawny tones that usually are present on the underparts of Amazonian. The vocalizations of these two species also are different; the song of Andean Motmot is more similar to the song of the Rufous Motmot (Baryphthengus martii) than it is to the song of Amazonian.
The following description is based on Stiles (2009), and refers to nominate momota; see also Geographic Variation:
Adult: Sexes similar. Large, long tail, possessing a blue crown and black eye mask lined with blue. The center of the dark blue crown is black, bordered below by a blue band ("diadem") that circles the head. The forepart of the diadem is sky blue to turquoise, becoming narrower and darker blue along the side of the head and broader and violet blue across the back of the head. There also usually is a rufous area on the nape, below the diadem. The black wedge of feathers covering the eye ("mask") gradually narrows to a point at the auriculars; the rear portion of the mask has a broad turquoise border, and there also is a broad turquoise border to the lower portions of the "mask" along the malars and below the eyes. Throat olive-green to green with an olive wash. Breast olive, variably washed to rusty to ochraceous, especially on the sides of the neck. Belly green, with little or no olive or rusty wash; flanks olive-green, tinged with ochraceous or tawny. Tibial feathers green to olive-green. Feathers in center of breast black, with narrow (often inconspicuous) turquoise blue margins. The rest of the breast is variably colored, from green with a faint hint of olive, to ochraceous-olive, or a distinct tawny tinge. The lower part of the undersides, including the crissum, are bluish-green. The tail is long, green basally and shading to blue distally. Racquets blue, with dusky to blackish tips.
Very little information. At one site in southern Venezuela, Willard et al. (1991) found "wing and tail molt on an early Dec. specimen and body molt on an early Apr. specimen; not molt noted on two specimens taken in late Feb. and early Mar."
Tarsi and toes: blackish gray
Data from specimens in the Field Museum of Natural History.
Total length: 46-48 cm (Ridgely and Greenfield 2001b)
Linear measurements (mm) of Momotus momota microstephanus (Stiles 2009)
| || || wing length (chord)|| tail length|| total culmen|
| male|| mean|| 133.33 ± 2.98|| 229.91 ± 10.52|| 43.56 ± 1.86|
| || range (n)|| 126.1-143.6 (66)|| 202.0-256.5 (59)|| 39.7-47.2 (65)|
| female|| mean|| 129.95 ± 3.54|| 224.19 ± 10.50|| 43.15 ± 1.85|
| || range (n)|| 123.3-138.6 (48)|| 191.5-244.5 (44)|| 39.6-47.2 (49)|
Mass: microstephanus, mean 120.7 ± 14.0 (range 95-153 g, n=21; Stiles 2009); nominate momota, mean 144.4 ± 7.2 g (range 125-155 g, n=5; Stiles 2009)