The ruddy treerunner (Margarornis rubiginosus), is a passerine bird which is endemic to the highlands of Costa Rica and western Panama. This treerunner is found in hills and mountains from 1200 m up to the timberline, in forests and adjacent edges and clearings. It builds a large enclosed oval nest 25 m high in the crown of a tree on the underside of a thick branch. The nest is camouflaged with mosses and epiphytes and has a downward pointing entrance tunnel at its base. The eggs are undescribed, but members of this family typically lay two white eggs.