Description wikipedia

The tropical gnatcatcher (Polioptila plumbea) is a small active insectivorous songbird, which is a resident species throughout a large part of northern South America. It was formerly considered as conspecific with the white-browed gnatcatcher and the Marañón gnatcatcher. The adult tropical gnatcatcher is 10 to 12 cm (3.9–4.7 in) long, and weighs 6 to 8 g (0.21–0.28 oz). Its "jizz" is similar to that of other gnatcatchers; a small bird with a relatively long thin bill, a long frequently cocked tail, grey upperparts and whitish underparts. The central rectrices are black, while the outer are white (consequently, the tail appears primarily black from above, white from below), and there is a white patch in the wing (caused by broad white edging to the tertials). Males of the nominate group have a contrasting black cap that reaches just below the eye, while this is lacking in females, which instead have a grey cap (same colour as back). Some females have an irregular black post-ocular patch. This is especially prominent in female of the subspecies atricapilla from north-eastern Brazil. Males of the white-browed gnatcatcher (bilineata group) resemble males of the nominate group, but the white of their underparts extends clearly above the eye, resulting in a more restricted black cap, which, however, often is connected with a fine black line from the nape to the rear of the eye. Females resemble males, but with the black of the cap replaced by grey, except for an irregular black patch in the post-ocular region (lacking in some females). As the white in both sexes extends above the eye, they appear rather "white-browed" (unlike the nominate group), resulting in the common name proposed for this group if considered a separate species. The tropical gnatcatcher has a thin buzzy gezzz call and a trilled swee see see si si si su su song. However, exact structure and tone of the voice varies greatly over its range.