The pearled treerunner (Margarornis squamiger) is a species of bird in the Furnariinae subfamily of the ovenbird family Furnariidae. It is found in Bolivia, Colombia, Ecuador, Peru, Venezuela, and possibly Argentina.
Taxonomy and systematics
The pearled treerunner has three subspecies, the nominate M. s. squamiger (d'Orbigny & Lafresnaye, 1838), M. s. perlatus (Lesson, 1844), and M. s. peruvianus (Cory, 1913).
Pearled treerunner M. s. perlatus in Yanacocha, Ecuador
Description
The pearled treerunner is 15 to 16 cm (5.9 to 6.3 in) long and weighs 14 to 19 g (0.49 to 0.67 oz). The sexes have the same plumage. Adults of the nominate subspecies have a well-defined yellowish buff supercilium that extends to the nape, a dull reddish brown line behind the eye, dull yellowish buff and dark brown ear coverts, and a dark brown moustacial area with tiny whitish spots that become streaks to the rear. Their forehead is dark brownish with pale rufous streaks and their crown dark reddish brown. Their collar is dull rufescent brown with black-outlined yellowish buff streaks. Their back, rump, and uppertail coverts are bright reddish brown. Their wing coverts are bright reddish brown, their primary coverts dark fuscous brown, and their flight feathers darker fuscous brown with rufescent edges. Their tail is bright reddish brown; the ends of the tail feathers lack barbs, giving a spiny appearance. Their throat is bright buff-yellow. Their breast and belly have a rufescent background. Their upper breast is dense with oval yellowish spots that have dark browish outlines; the spots become stretched out and less distinct by the lower breast and continue onto the belly. Their flanks are darker rufescent than the belly, with longer spots, and their undertail coverts are rufescent brown with a few blackish-edged buff-yellowish streaks. Their iris is brown to dark brown, their maxilla black to gray, their mandible whitish horn to purplish pink (sometimes with a dark tip), and their legs and...
