A dark brownish-gray cuckoo with an unusually long tail and barred underparts. Found in the understory and at middle levels of humid forest at low and middle elevations. Shy and retiring, most easily found by voice. Very similar to Olive Long-tailed Cuckoo and best separated by voice, but also identified by darker upperparts, broader barring on the underparts, and richer rufous on the undertail. There are two main vocalizations: a quick series of three rising whistles, and a long, rapid series of whistles that slows and falls slightly toward the end. In the far western part of the range, the three whistles are slow and each one is progressively higher in pitch; elsewhere, the whistles are fast and identical.