Adults of the nominate subspecies L. a. amaurocephalus have a sepia brown crown and a paler nape.

[4][5][6] The other subspecies of the sepia-capped flycatcher differ from the nominate and each other thus: Both sexes of all subspecies have an iris whose color can be from light brownish yellow to dark brown, a black or dark brown bill with sometimes a pale base to the mandible, and legs and feet of various shades of gray.

It mostly hover-gleans or snatches fruit and insects in short sallies from a perch, and occasionally captures prey on the wing.

[4][8][9][10][11][12][excessive citations] The sepia-capped flycatcher's breeding season has not been defined but includes at least April and May in Mexico.

Its nest is a globe with a side entrance, made from moss, leaf stems, and grasses and lined with seed down.

It is typically hung from a vine or an exposed root beneath an overhanging log, rock, or stream bank.

Various authors have described the sepia-capped flycatcher's song as "a harsh, almost explosive SKET'a'a'j'j'j or SKET'd'd'r'r'r', last part chattery and vibrating"[11] , "a fast, sputtering chatter that trails off toward end, e.g., dre- d'd'd'd'd'd'd'dew, sometimes introduced by a sharper, more emphasized note"[12], and "an abrupt, loud, slightly falling, semimusical chatter: ski'i'i'i'i'i'i'i'eew"[13].

It has an extremely large range; its estimated population of at least 500,000 mature individuals is believed to be decreasing.