The medium tree finch (Camarhynchus pauper) is endemic to the island of Floreana in the Galapagos Islands, Ecuador (BirdLife International 2008; Harris 1982, p. 150; Sibley and Monroe 1990, p. 771). It is one of the 14 species of Darwin's finches, collectively named in recognition of Charles Darwin's work on the theory of evolution (Grant 1986, p. 6), and is approximately 12.5 centimeters (cm) (5 inches (in)) in length (BirdLife International 2008; Harris 1982, p. 150). The medium tree finch mainly occurs in the moist highland forests (i.e., the Scalesia zone, named for the dominant plants, Scalesia spp., found in this zone) (Christensen and Kleindorfer 2008, in preparation; Stewart 2006, p. 193), primarily above 300 m (984 ft) (Castro and Phillips 1996, p. 130).