Both coastal ponds and the Laguna Madre must be considered as vital parts of the Texas winter range of redheads. The continued integrity of the Laguna Madre of Texas and the Laguna Madre of Tamaulipas as functional ecosystems is essential to the maintenance of the western Gulf of Mexico as the major winter range of this species of migratory waterfowl. Most important among current issues are open-bay disposal of sediments from maintenance dredging of the channel of the Gulf Intracoastal Waterway in the Laguna Madre of Texas, and its subsequent effect on light transmission and seagrass photosynthesis. Other prominent issues highlighted by the close linkage between redheads and shoalgrass are the persistent brown tide in the Laguna Madre and its effect on light transmission and the continuing widespread decline of shoalgrass meadows. A declining trend in winter food resources in the face of historically high redhead numbers could reverse the positive outlook for redheads and, conceivably, could even lead to a population crash.
Current focus is therefore on development of a redhead population model.
The population model will include management options which can be evaluated for their effects on numbers of redheads. We investigated 13C values of breast and leg muscle, liver, gizzard, and abdominal fat from 259 Redheads obtained from the Texas winter range, South Dakota breeding grounds, and from a molting lake in Manitoba. We also measured 13C values of representative aquatic biota, including known Redhead foods, from these areas. We tested the hypothesis that, as Redheads change from a seagrass diet in winter, to a mixed diet while breeding, and then to a postbreeding diet of submerged aquatic vegetation, the isotopic composition of their tissues will change also. Photo Gallery Redhead breeding grounds in the prairies potholes of North America.