White-flanked Antwren

The white-flanked antwren is 9 to 10.5 cm (3.5 to 4.1 in) long and weighs 5 to 10.6 g (0.18 to 0.37 oz) with some variation in weight among the subspecies. It is a smallish bird with a short tail. Adult males of the nominate subspecies M. a. axillaris have a dark gray head, neck, back, and rump with a hidden white patch between the shoulders. Their tail is blackish with white tips to the feathers. Their wings are blackish with white tips on the coverts and gray edges on the flight feathers. Voice: The white-flanked antwren's song differs among the subspecies. That of M. a. axillaris, M. a. heterozyga, and M. a. fresnayana is "a rapid uncountable series of abrupt notes, somewhat low-pitched...dropping sharply in pitch and gaining in intensity at beginning, then more or less levelling". Its pace varies somewhat across its area. The song of M. a. albigula and M. a.