Myiothlypis are generally small, drab, and flit along on or near the ground. Buff-rumped Warbler is distinctive due to the buff rump. Where found it is virtually unmistakable, and is one of the most common ground-dwelling insectivore in many riparian habitats. Found in lowland forests, with drab upperparts and a buff-rumped tail. Occasionally birds exhibit dark spotting on the breast.
The Riverbank Warbler, found in the Amazon Basin and southeastern Brazil, is very similar to the Buff-rumped Warbler, although lacking the buff rump. Since the buff rump is used constantly in signaling, this provides a very good distinction between the two species. The Riverbank Warbler does not have much range overlap with Buff-Rumped Warbler, which presumably helps prevent hybridization or contact. Thought to be generally allopatrically distributed, their habitats would overlap if they were to occur in the same range, as Riverbank Warbler is usually also found along water.
Described by Wetmore as “Crown blackish-olive, becoming dark olive on rest of upper surface to upper tail coverts, which are warm buff; wing coverts and remiges blackish, edged dark olive; basal half of tail ochaceus-buff, outer half dark brown; fine superciliary warm buff; undersurface white mottled with varying degrees of warm buff and dark olive” (Wetmore 1965). For more information see Geographic Variation.
First-year/adult birds have a complete molt, but post-juvenile molt is unknown. This molt is presumed to occur after breeding, although the timing is not certain (Curson 1994).
Tarsi and toes: Brown (Curson 2010)
From Curson (Curson 1994). Sample sizes are unknown.
|Weight (g) (averaged)||14.9||14.9|
From Wetmore (Wetmore 1954). Means are presented in parentheses.
Myiothlypis fulvicauda leucogpygius
Males (10 from western Panamá) Females (10 from western Panamá and Costa Rica)
|Wing||61.0-66.9 (64.4)||60.4-65.5 (62.7)|
|Tail||50.5-55.7 (52.4)||47.1-54.6 (51.2)|
|Culmen from base||12.7-14.9 (14.1)||12.8-14.5 (13.8)|
|Tarsus||21.3-22.9 (21.3)||19.0-22.6 (21.2)|
Myiothlypis fulvicauda semicervinus
Males (10 from eastern Panamá) Females (10 from eastern Panamá)
|Wing||61.5-66.0 (63.6)||58.9-64.0 (60.6)|
|Tail||49.0-54.8 (51.7)||45.8-52.5 (49.7)|
|Culmen from base||12.7-15.3 (13.8)||12.3-14.8 (13.5)|
|Tarsus||19.9-22.3 (21.4)||19.-22.6 (21.2)|