Ramphastos ambiguus Swainson, 1823

Common Name and Size

Ramphastos ambiguus, commonly known as the yellow-throated toucan, measures 47 to 61 cm (19 to 24 in) in total length and weighs 584 to 746 g (1.3 to 1.6 lb).

Subspecies Body Dimensions

Across its three recognized subspecies, overall body dimensions differ very little.

Sexual Bill Length Dimorphism

In all three subspecies, females have shorter bills than males: male bill lengths range from 15.1 to 19.8 cm (5.9 to 7.8 in), while female bill lengths range from 12.9 to 16.0 cm (5.1 to 6.3 in).

Other Sexual Body Measurements

Other body measurements do not differ notably by sex; wing chord measures 20.4 to 24.8 cm (8.0 to 9.8 in), tail length measures 14.0 to 16.2 cm (5.5 to 6.4 in), and tarsus length measures 4.7 to 5.5 cm (1.9 to 2.2 in).

Plumage Similarity

All three subspecies have nearly identical plumage.

Main Body Plumage

Their body is mostly black, with a maroon tint on the hindneck and upper back, and white uppertail coverts.

Throat and Breast Plumage

Their face, throat, and upper breast are bright yellow, with white and crimson bands positioned below the breast.

Vent Plumage

Their vent and undertail coverts are bright red.

Periophthalmic Skin Color

The color of the bare skin surrounding the eye differs between subspecies: it is sky blue in the nominate subspecies R. a. ambiguus, yellow-green in R. a. abbreviatus, and varies between yellow and bright green in R. a. swainsonii.

Subspecies Bill Variation

The structure and color of the bill also differs between subspecies.

Shared Maxilla Traits

All three have a mostly yellow maxilla, with a greenish yellow stripe along the culmen and a thin black line at the bill base.

Subspecies Mandible Color

The nominate R. a. ambiguus and R. a. abbreviatus have black mandibles, while the mandible of R. a. swainsonii is maroon to reddish chestnut brown.

R. a. swainsonii Habitat

The chestnut-mandibled subspecies R. a. swainsonii primarily inhabits lowland evergreen primary forest, and also occurs in gallery forest, older secondary forest, and well-treed parks and gardens.

R. a. swainsonii Habitat Avoidance

It avoids dry forest and large open areas, but can be found in plantations with fruiting trees that border existing forest.

Black-mandibled Subspecies Habitat

The two black-mandibled subspecies usually occupy the interior of humid primary montane forest, and also occur at forest edges, in forest clearings, and in older secondary forest.

R. a. swainsonii Elevation Range

Elevation ranges for the chestnut-mandibled subspecies vary by country: it occurs from sea level up to 1,000 m (3,300 ft) in Ecuador, below 2,000 m (6,600 ft) in Colombia, and up to 1,200 m (3,900 ft) in Costa Rica.

Black-mandibled Elevation Range

For the black-mandibled subspecies, elevation ranges are between 1,000 and 1,600 m (3,300 and 5,200 ft) in Ecuador, and up to 2,500 m (8,200 ft) in Colombia.