Wildlife Society Bulletin. vol 22, no 2. p. 165-171. Zink RM, Weller SJ & Blackwell RC. (1998). Molecular phylogenetics of the avian genus Pipilo and a biogeographic argument for taxonomic uncertainty. Molecular Phylogenetics & Evolution. vol 10, no 2. p. 191-201. olive sparrow Birds of Central America Birds of the Rio Grande valleys Birds of the Yucatán Peninsula Birds of Belize Birds of Nicaragua olive sparrow olive sparrow