Sierra Madre ground warbler  The Sierra Madre ground warbler ("Robsonius thompsoni") is a species of passerine bird in the family Locustellidae. It is endemic to the island of Luzon in the Philippines. The species was first described by the ornithologists Peter Hosner and colleagues in 2013 and given the binomial name "Robsonius thompsoni". The specific epithet was chosen to honour the ornithologist Max C. Thompson. This species is placed in the genus "Robsonius" that was introduced by the English ornithologist Nigel J. Collar in 2006. The Sierra Madre ground warbler feeds on insects and lives in tropical understories. It is a ground-walking songbird — rotund, with strong legs and weak wings — and it appears that it can barely fly. It tend to inhabit dense forest understories, where they feed on insects. Their song is extremely high in pitched and it is difficult to locate the source of the sound in the forest — they always sound like they are far away, even when they are almost at your feet. The bird looks similar to the other two species of ground warblers on the island of Luzon, the Bicol ground warbler and the Cordillera ground warbler, and probably for this reason that it was not recognized as an separate species. The three species of ground warblers are similar in size, shape and in the coloration of their juvenile plumage, but they differ from one another in their adult plumage coloration. Since they are so alike they were always thought to be the same species, until a DNA test was conducted where it became very obvious that these species were in-fact not the same. One way to tell the difference between a Bicol ground warbler or a Cordillera ground warbler and a Sierra Madre ground warbler is that the plumage of an adult bird is variegated brown, gray and red. The Sierra Madre ground warbler is also 20 centimeters long with relatively long legs.