Birds from the Plains of Tehuantepec, Oaxaca, Mexico (Notes) (Report‪)‬

The Isthmus of Tehuantepec in southeastern Mexico is the narrowest strip of land separating the Gulf of Mexico and the Pacific Ocean. At this terrestrial constriction, Nearctic and Neotropical biotas overlap, biogeographic barriers have promoted an elevated degree of speciation, and routes of migratory birds are funneled (Binford, 1989; Peterson et al., 1999; Perez-Garcia et al., 2001; Peterson et al., 2003; Rodriguez-Contreras, 2007). The Oaxacan portion of the Isthmus of Tehuantepec is a center of endemism for terrestrial vertebrates and the Pacific region has been designated a high-priority Endemic Bird Area by BirdLife International for range-restricted species such as the cinnamon-tailed sparrow (Aimophila sumichrasti) and rose-bellied bunting (Passerina rositae). Historically, the Oaxacan Isthmus of Tehuantepec has been one of the most visited regions in the state, if not the nation, by ornithologists (Binford, 1989; Navarro et al., 2004). Indeed, one of the first collecting localities in Mexico was Tehuantepec City in 1825 under the pioneering efforts of the Prussian collector F. Deppe (Stresemann, 1954). Notable ornithological publications on the avifauna of the Oaxacan Isthmus of Tehuantepec include the collecting efforts of A. L. F. Sumichrast on mostly the Pacific coastal plain (Lawrence, 1875; Sumichrast, 1881) and W. W. Brown at Chivela (Bangs and Peters, 1928), as well as records of specimens and observations of Binford (1989) in the Isthmus and of W. J. Schaldach and collaborators on principally the Atlantic slope (Schaldach et al., 1997). Records accumulated from these and other efforts have provided a baseline understanding of regional distribution of species, both geographically and temporally. As emphasized by Forcey (2002a), however, a great deal of our understanding of the avifauna of Oaxaca is based solely on collecting efforts and many aspects of the ecology of its birds remain to be studied for even the most abundant taxa. Additionally, the majority of ornithological expeditions to the Oaxacan Isthmus were prior to 1969, with few investigations during the past 4 decades.