The Oahu elepaio is a small (12.5 grams (0.4 ounces) average weight, 15 centimeters (5.9 inches) total body length) monarch flycatcher (Monarchidae; VanderWerf 1998, page 1). It is dark brown above and white below, with light brown streaks on the breast. The tail is long (6.5 cm, 2.6 inches) and often cocked up at an angle. Adults have conspicuous white wing bars, a white rump, and white tips on the tail feathers that are often displayed. The throat is white with black markings in both sexes, but males tend to have more black than females, especially on the chin (USFWS 2006, page 2-2).