About Polioptila melanura Lawrence, 1857
The black-tailed gnatcatcher (Polioptila melanura Lawrence, 1857) measures 4.5 to 5 inches long overall, much of this length being its long black tail that has white outer feathers. Its upper body is blue-grey, and its underparts are white. While this species resembles the blue-grey gnatcatcher, the two can be told apart by how much black coloring is present in their tail feathers. In summer, breeding male black-tailed gnatcatchers have a solid black cap that extends down to their eyes. Females and non-breeding winter males do not have this black cap, which makes them very hard to distinguish from blue-grey gnatcatchers. The most reliable way to separate the two species is by looking at the underside of the tail: a blue-grey gnatcatcher’s tail is mostly white from below, while a black-tailed gnatcatcher’s tail is predominantly black from below. Like other gnatcatcher species, the black-tailed gnatcatcher forages for small insects and spiders in desert shrubs, and may produce harsh, scolding calls while foraging.
