Sciurus stramineus Eydoux & Souleyet, 1841

Taxonomy and Build

Guayaquil squirrels (scientific name Sciurus stramineus Eydoux & Souleyet, 1841) are relatively heavily built squirrels, with an average weight of around 470 grams (17 oz).

Body and Tail Length

Their head-body length ranges from 18 to 32 centimetres (7.1 to 12.6 in), and they have a long tail that measures 25 to 33 centimetres (9.8 to 13.0 in), which is long in proportion to their body.

Coat Variability

While the scientific name translates to "straw-coloured squirrel", the coat colour of this species is actually highly variable. Past efforts to classify different subspecies based on coat colour are no longer accepted, as there was no clear distinction between the proposed groups.

Colour Morph Counts

At least two main colour morphs exist for the species.

Paler Morph Traits

The paler morph, which is more common in Peru, has pale grey fur grizzled with white across most of the body, a buff rump, a white or pale yellow patch on the back of the neck, and grey underparts.

Darker Morph Traits

The darker morph, which is more common in Ecuadorian lowlands, has grey fur on the forequarters, dull orange hindquarters, grizzled black and white shoulders, and grey underparts.

Morph Individual Variation

Even these two morphs show high individual variation: some individuals lack the shoulder or rump patches, and others have tawny or even reddish underparts instead of grey.

Melanistic Morph Traits

A third, rarer melanistic morph has also been recorded; this morph has nearly all-black fur across the body, with only a white patch on the collar and occasional white spots on the back.

Shared Morph Traits

All morphs of Guayaquil squirrel have black ears and a slender grey tail.

Species Distinction Feature

The slender grey tail can be used to distinguish this species from the only other tree squirrel native to Ecuador, the red-tailed squirrel.

Native Distribution

Guayaquil squirrels are found in the wild only in southwestern Ecuador and northwestern Peru.

Introduced Population

A small population has also been introduced to parks in Lima.

Habitat and Elevation

They live in a range of forest types, from dry to humid, along the western slopes of the Andes, at elevations between 300 and 2,000 metres (980 and 6,560 ft).

Human-Altered Habitat

They have also been recorded living in coffee plantations.

Current Subspecies Status

No subspecies of Sciurus stramineus are currently recognised.