The Rufescent Tiger-Heron generally is the least-frequently encountered of the three species of Tigrisoma, and is considered uncommon to rare. This medium-sized heron is found around swamps, marshes, and sluggish streams at lower elevations. Usually seen singly. Adults are distinctive with their bright rufous head and neck. Juveniles are buffy with uneven black barring. Juveniles essentially identical to juvenile Fasciated Tiger-Heron, but note different habitat.
Tigrisoma lineatum subspecies - Tigrisoma lineatum marmoratum The Rufescent Tiger-Heron’s head, sides of the head, and long, thick neck are rich chestnut brown to rufous cinnamon. The bill is relatively long, up to 10 cm, appearing slightly up tilted, and varies in color according to age and season, in ways that are not well understood. The upper bill is dark (olive black, yellow brown, or black) and the lower bill is light (yellow, green or pale olive buff). Skin at the base of the bill is yellow. The lores appear to have three stripes running from the bill, yellow above and below, grey in the center. The skin around the eye is also yellow. The feathered chin is white. The irises are yellow, but sometimes pale brown. The neck is relatively long and can be snake-like as its held out while the bird is feeding. The foreneck has a wide, rufous vertical stripe brown in its center, bordered by white stripes on either side, which are particularly effective when the bird raises its head or assumes a Bittern posture.
The back and tail are green black and wings dark grey, all having multiple delicate brown lines, speckles, and flecks that extend variably onto the head (Hancock 1999). Not visible, but a character distinguishing this species from the other tiger herons, is a lack of interscapular powder-down patches. The flanks are slate, horizontally striped with thin white lines, also variable among individuals. The abdomen is grey with an ochre tinge. The under wing is slate with sharp white banding. The legs, with relatively long tarsi, and are dark olive or black in front, and green behind. In courtship the soft parts brighten and the irises turn bright red.
VARIATION: The sexes are alike, although there is an indication of sexual difference in plumage details (Hancock 1999). Geographic variation is recognized by two subspecies. Lineatum, as described above, is the smaller of the two and has less extensive throat feathering. Marmoratum is somewhat larger. Its throat feathering extends a short way over the base of the lower mandible, as in the Fasciated Tiger-Heron. Birds from Argentina have a dark crown, sometimes with bold streaking and were formerly treated as a separate species, Tigrisoma bolivianium. However, dark on the forehead, sometimes with additional black streaks occur elsewhere within the species so the black cap appears to be within the range of individual variation of the species, and these birds are considered to be marmoratum
