The nest of the Pearled Treerunner (Margarornis squamiger)

Abstract

The Pearled Treerunner (Margarornis squamiger) is a small ovenbird (Furnariidae) inhabiting the upper strata of Neotropical montane forests. Little is known of its breeding habits despite its wide distribution and abundance within appropriate habitat. The genus Margarornis is considered closely related to Premnoplex barbtails, but details of nest architecture supporting this relationship are unavailable. Here we provide the first detailed description of nest architecture for the Pearled Treerunner from a nest encountered in northwest Ecuador. The nest was a tightly woven ball of moss and rootlets, similar in shape to that of the Spotted Barbtail (Premnoplex brunnescens) and presumably built in a similar manner. Nest architecture and nestling behavior support a close relationship between Margarornis and Premnoplex.