The Ruddy-capped Nightingale-thrush, Catharus frantzii, is a small thrush which is a resident breeder in highlands from central Mexico to western Panama. Its closest living relatives seems to be the North American species complex containing of the Veery, the Gray-cheeked, and Bicknell's Thrush (Winker & Pruett, 2006).
It is found in the undergrowth of wet mountain oak and conifer forests and second growth, typically from about 1350 m to 3500 m altitude. The nest is a bulky lined cup constructed 1-4 m high in dense undergrowth or a thicket, often near water. The 2 brown-blotched greyish or greenish-blue eggs are incubated by the female alone for 15-16 days to hatching, and the young are fed by both parents for 14-16 days more to fledgling.
This species is 15 to 18 cm in length and weighs 28 g. The adult has olive-brown upperparts, a rufous crown and nape, pale grey underparts, becoming whitish on the belly, and an orange lower mandible. The juvenile is darker faced, has pale centres to the upperpart feathers, brownish flanks and breast, and dark barring or spots on the belly. Several poorly-defined subspecies have been defined differing in the exact tone of the upper and underpart plumage.
The Ruddy-capped Nightingale-thrush will normally forage on the forest floor, alone on in pairs, progressing in hops and dashes with frequent stops. It turns leaf litter in typical thrush fashion seeking insects and spiders, and also eats small fruits. This bird's song is a beautiful rich and varied whistle, shee-vee-li-ee-ree, and call is a high thin seet or whooeet.
The binomial commemorates the German naturalist Alexander von Frantzius.