Adults of most subspecies are typically dark slate grey above; the tail is tipped with white and has three to six narrow white bars. The throat is pale grey, shading to the darker slate of the crown. The rest of the under parts, including the under-wing coverts, are white, finely and clearly barred with black or dark grey. The upper breast is a darker grey. The primary remiges are dark brownish-grey with off-white bars on the inner webs. One subspecies, M. r. zonothorax from the East Andean foothills, is polymorphic, and also occurs in a brown morph, where most of the upperparts, head, and chest are brown or rufous instead of grey. The nominate subspecies, which is found from southeastern Brazil south to northeastern Argentina and west to Paraguay, appears to only occur in the rufous-brown morphotype, as also suggested by its scientific name, M. r. ruficollis. The eyes are cream to light orange brown; the bill black, becoming yellow at base of the lower mandible; the cere, lores, and orbit are yellow, and the legs are orange-yellow.
Ecology
Barred forest falcons mainly use mature upland forest. In Central America, the species is generally restricted to mature tropical forest. In South America, however, the barred forest falcon lives in other kinds of forest and woodland, even relatively arid. For example, in the Amazon biome it occurs most often in secondary forest, gallery forest, tidal swamp forest, semideciduous forest, and forest edges. In Acre, Brazil, the barred forest falcon is reported to prefer disturbed forest types, both natural secondary and man made, including bamboo and more open seasonally drier forest on rocky outcrops, but generally it is a bird that avoids habitat where human influence is too pronounced, and requires primary or mature secondary forest to persist in any location. It is not commonly seen, but based on voice, it appears to be uncommon to fairly common throughout a large part of its range. This, combined with its large range, has led to it being classified as a species of Least Concern by the IUCN. It is rare on the eastern slope of the ColombianCordillera Oriental, where it was recorded in primary forest and old secondary forest, in a narrow altitude band between 3,300 and 4,900 ftabove mean sea level, and first encountered in the Serranía de las Quinchas only in 2000/2001. Second-growth forest in these mountains is dominated by trees like Melastomaceae and trees are generally overgrown with epiphytes and hemiepiphytes like Coussapoa. This species feeds primarily upon small birds, mammals and squamates. Like Accipiter hawks, they often hunt prey by sitting quietly on tree branches and waiting for their victims to appear. When the prey arrives, the forest falcons quickly ambush them, attempting to catch them with a brief, flying pursuit. However, forest falcons also use other techniques to hunt prey, such as chasing prey on foot, following army ant swarms, and acoustical luring of birds, by means of a "facial disc". The species has also been recorded to snatch animals from traps or cages, for example during mark-recapture studies. Forest falcons do not build a nest, but lay their two or three white eggs in cavities in trees. Laying occurs mainly late in the dry season, with hatching taking place at the onset of the rainy season, a time of increasing prey abundance. Eggs hatch 33–35 days after being laid, and nestlings fledge 35–44 days after hatching. Radio-tagged fledglings dispersed from their parents' territories within four to seven weeks after fledging, presumably achieving independence at that time. Nesting territories were occupied year after year; and high mate fidelity is seen.
