About Psaltriparus minimus (J.K.Townsend, 1837)
The American bushtit, with the scientific name Psaltriparus minimus (J.K.Townsend, 1837), measures 100–110 mm (3.9–4.3 in) in length and weighs 4.5–6 g (0.16–0.21 oz), making it one of the smallest passerines in North America. Its plumage is mostly gray-brown, and it has a large head, short neck, long tail, and a small, stubby beak. American bushtits show distinct physical traits that vary by sex and habitat region. Males have dark brown to black eyes, while adult females have yellow eyes. Coastal populations of American bushtits typically have a brown cap or crown, while inland populations have a brown facial mask. Populations in Mexico and Central America have a black cheek patch. This black cheek feature is not found in the northern portion of the species' range; in the United States, it is only found near the Mexican border, mainly in Texas. No individuals with black ear patches in this border location are adult females, and most are juvenile males that have one or two dark facial lines rather than a full patch. The black-eared variant becomes much more common starting from the northeastern Mexican highlands and extending further south. In this southern range, all males have a full black ear patch, and even mature females have a black arc covering their eyes, usually with an additional black line across the eyes.
