The Avifauna of the Sierra del Carmen of Coahuila, Mexico

Abstract

In the desert of northern Coahuila, Mexico, lies a rugged mountain system collectively known as the Sierra de1 Carmen.The high northern part of this sierra is about 30 miles in extent along a north-northwest axis and it supports conifer and pine-oak vegetation that is well isolated from other such ecologic formations of significant area1 extent.The Sierra consists principally of an elevated limestone plateau, deeply dissected, and with steep escarpments, especially to the west.The top of the plateau in most places is about 8000 feet altitude.The northern end of the Sierra is less than 50 miles southeast of the higher parts of the Chisos Mountains in the Big Bend National Park of Texas.The two mountain areas are part of the same system of uplifts, although of course they are separated by the Rio Grande Valley and are composed of different types of rock.The upper levels of the Sierra de1 Carmen have seldom been penetrated by naturalists and no extensive investigation of the bird life of the area has previously been undertaken.The birds of the lower Chisos Mountains have been well studied (Van Tyne and Sutton, 1937) and considerable data are available on the birds of the mountains of extreme southern Coahuila at the northern end of the Sierra Madre Oriental (Burleigh and Lowery, 1942).In the summer of 1936 Ernest G. Marsh, Jr., botanist, was commissioned by the United States National Park Service to make a biological survey of the Sierra de1 Carmen.Incidental to his general objectives, observations on birds were made and forty-four specimens were deposited in the