Yellow-throated Toucan Ramphastos ambiguus

  • Order: Piciformes
  • Family: Ramphastidae
  • Polytypic: 3 subspecies
  • Authors: Ari A. Rice, Jason D. Weckstein, and J. Engel
Sections

Appearance

Distinguishing Characteristics

Yellow-throated Toucan is a large species distinguished from others by its size, yellow face and throat, bicolored yellow and black or chestnut bill, and loud yelping voice. The upperparts are black, with a white rump, and the undertail coverts are red.

Similar Species

In Central America, Yellow-throated Toucan can be confused with the slightly smaller Keel-billed Toucan (Ramphastos sulfuratus). Although the two species often overlap in range and habitat, Yellow-throated can be distinguished by its solid, bicolored bill (which is very different from the bill of Keel-billed, which is primarily green, with blue, red, and orange markings). These two species are also easily distinguished by voice. Yellow-throated Toucans have distinctive yelping calls that are very different from the croaking calls of Keel-billed Toucan (Short and Horne 2001).

On the western slope of the Andes (Colombia and Ecuador), Yellow-throated Toucan overlaps with the very similar Choco Toucan (Ramphastos brevis). Both species, in fact, once were considered conspecific, but studies have shown that the two belong to different clades (Weckstein 2005, Patané et al. 2009). Morphologically they are almost identical, although Yellow-throated Toucan is larger, the dark portions of its bill are paler (dark chestnut brown as opposed to black), and the bill is longer and broader, with a rounded rather than keel shaped culmen (although this is difficult to assess in the field and is subtle even in specimens). The two species are most easily distinguished by voice. Yellow-throated Toucans have distinctive yelping calls that are very different from the croaking calls of Choco Toucan (Short and Horne 2001).

Detailed Description

The following description is based on Short and Horne (2001), and refers to nominate ambiguus; see also Geographic Variation:

Adult male: Body black except for face, throat, upper breast, and tail coverts. Hindneck and upper back black with maroon-reddish tint. Feathers turn browner with wear. Face, throat, upper breast, and auricular areas bright yellow. Yellow extends to middle breast and is bordered below by bands of white and crimson. Uppertail coverts white; vent and undertail coverts deep to bright red. Bill is long, and curved along the culmen, especially near the tip; for bill colors, see Bare Parts.

Adult female: Similar to male in all respects except for a shorter, "blockier" bill (Short and Horne 2001).

Immature: Apparently undescribed for nominate ambiguus. Immature of swainsonii (which presumably is very similar) is "Sooty-black, above tinged with dull chestnut-maroon; red of bib and crissum paler and less extensive; yellow of bib duller; lower bill duskier; young birds do not attain full-sized bills for several months after fledging" (Stiles and Skutch 1989).

Molts

Timing of molt varies depending on latitude: in swainsonii, annual molt occurs August-April in Costa Rica, June-February in Panama and Colombia, and August-February in Ecuador (Short and Horne 2001). There seems to be no information on molts in ambiguus and abbreviatus.

Bare Parts

Adult: Bill is very long (see Measurements). Maxilla largely yellow, with a greenish yellow stripe running along the culmen, and a thin black basal line that borders the base. Mandible black (ambiguus, abbreviatus) or maroon to reddish chestnut brown (swainsonii). A narrow black line surrounds the eye. Bare orbital skin varies geographically and individually: sky blue (ambiguus), yellow green (abbreviatus), or bright green, greenish-yellow, or plain yellow (swainsonii). Iris color also is quite variable, ranging from gray, to brown, to dark green, to olive-yellow (Short and Horne 2001). Tarsi and toes blue or blue gray.

Immature: Bill is shorter (almost keel-shaped) and less contrastingly marked: it is often dull yellow-brown in young birds. Iris brown or gray brown (Short and Horne 2001).

Measurements

The following measurements are from Short and Horne (2001), except where noted. The format of these measurements is as follows: range (mean).

ambiguus:

wing length (chord)

220-248 (229.2) mm (male, n = 27); 206-248 (219.5) mm (female, n = 22)

tail length

155-173 (162.4) mm (male, n = 24); 148-165 (158.1) mm (female, n = 20)

bill length (chord)

153-198 (167.26) mm (male, n = 27); 131-151 (143.31) mm (female, n = 23)

tarsus length

51-59 (54.7) mm (male, n = 24); 47-55 (51.43) mm (female, n = 22)

mass

620-740 g (male, n = 3); 599 g (female, n = 1)

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abbreviatus:

wing length (chord)

217-243 (224.4) mm (male, n = 8); 207-234 (217.5) mm (female, n = 17)

tail length

no information

bill length (chord)

152-175 (164.5) mm (male, n = 8); 129-148 (141.24) mm (female,n = 17)

tarsus length

no information

mass

no information

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swainsonii

wing length (chord)

217-244 (228.1) mm (male, n = 38); 204-230 (216.9) mm (female, n = 23)

tail length

140-162 (154) mm (male, n = 10); 144-158 (151.2) mm (female, n = 5)

(Rice, Weckstein, and Engel, from specimens at the Field Museum of Natural History)

bill length (chord)

151-193 (170.95) mm (male, n = 38); 132-160 (145.39) mm (female, n = 23)

tarsus length

50.34-54.95 (52.84) mm (male, n = 10); 48.84-53.06 (50.784) mm (female, n = 5)

(Rice, Weckstein, and Engel, from specimens at the Field Museum of Natural History)

mass

681-746 g (male, n = 8); 616-680 g (female, n = 3)

Recommended Citation

Rice, A. A., J. D. Weckstein, and J. Engel (2010). Yellow-throated Toucan (Ramphastos ambiguus), version 2.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.bkmtou1.02