The Pinnated Bittern is a large heron, measuring between 25–30 in (63.5–76 cm) with a weight of roughly 1.8 lb (800 g)[citation needed]. Sexes are similarly plumaged, but females tend to be smaller than males and have brown instead of black on the tail.
Both adults and immatures are generally buffy, though heavily marked with cryptic patterning. Juveniles tend to have a somewhat more reddish ground color. The throat is unmarked white, the foreneck is white broadly streaked with pale brown, and the rest of the neck is buff with thin black barring. The breast and belly are white with broad pale brown streaks, while the back is buff, heavily streaked and barred with black. Rectrices are black in males and brown in females; the slate-grey remiges create a conspicuous two-toned effect in flight.
The bill is stout and strong, yellowish overall with a dusky upper mandible. The bare facial skin is bright yellow, with a brown line running across the lores. The legs are greenish-yellow, and the iris is yellow.
Both adults and immatures are generally buffy, though heavily marked with cryptic patterning. Juveniles tend to have a somewhat more reddish ground color. The throat is unmarked white, the foreneck is white broadly streaked with pale brown, and the rest of the neck is buff with thin black barring. The breast and belly are white with broad pale brown streaks, while the back is buff, heavily streaked and barred with black. Rectrices are black in males and brown in females; the slate-grey remiges create a conspicuous two-toned effect in flight.
The bill is stout and strong, yellowish overall with a dusky upper mandible. The bare facial skin is bright yellow, with a brown line running across the lores. The legs are greenish-yellow, and the iris is yellow.
