ABSTRACT
The Texas Coast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Coastal Habitats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 The Rice Prairies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Declines in Wetland Habitats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 The Northern Pintail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Trends in Northern Pintail Abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Factors Potentially Limiting Population. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Winter Survival . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Linking Optimal Migration Theory and Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
The Texas coast ranks as one of the highest priority areas for bird conservation in North America because of its great abundance and diversity of bird life. This region provides breeding, wintering, or migratory stopover habitat for about 400 species of birds (Rappole and Blacklock 1994; DeGraaf and Rappole 1995). Further, potentially more than 100 million birds migrate through this region each fall and spring. Some species rely heavily on the Texas coast for part or all of the annual cycle. For example, about 75% of all redhead ducks (Aythya americana) spend winter in the Laguna Madres of Texas and Tamaulipas (Weller 1964; U.S. Fish and Wildlife Service, unpublished data, 2004); however, all these birds most likely use Texas coastal areas during migration and portions of the winter. Similarly, most reddish egrets (Egretta rufescens) breed in Texas estuaries, whereas a large proportion of western Gulf coast mottled ducks (Anas fulvigula) rely on coastal habitats in Texas throughout the annual cycle. Many species of neotropical migrant birds breed in temperate regions of North America and migrate to and from wintering grounds in Central and South America. A narrowing of the North American continent along with an east-west restriction of habitats suitable to many species causes large-scale convergence of migratory corridors along the Texas coast (Lincoln et al. 1998).
