Black-capped Gnatcatcher

The black-capped gnatcatcher (Polioptila nigriceps) is a small songbird in the family Polioptilidae. It is found in Mexico and the United States. == Taxonomy and systematics == The black-capped gnatcatcher has at times been treated as conspecific with the white-lored gnatcatcher (Polioptila albiloris). Two subspecies are recognized, the nominate Polioptila nigriceps nigriceps and P. n. restricta. == Description == The black-capped gnatcatcher is 10 to 12 cm (3.9 to 4.7 in) long and weighs 5 to 8 g (0.18 to 0.28 oz). Adults are blue-gray on the upperparts with white underparts. They have a long slender bill and a long black tail with mostly white outer feathers. Males in alternate (breeding) plumage have a glossy black cap. The female's gray upperparts have less of a bluish tint but are otherwise similar to the non-breeding male. This species is very similar to the black-tailed gnatcatcher (P. melanura). == Distribution and habitat == The nominate black-capped gnatcatcher is found in western Mexico from central Sinaloa south to Colima. P. n. restricta is found mostly in western Mexico from eastern Sonora south to northern Sinaloa. It has occasionally nested just across the U.S. border in the Madrean sky islands area of southernmost Arizona.…