Changes in Waterfowl and Wetland Abundance in the Chenier Plain of Texas 1970s-1990s
Trends in numbers of ten species of ducks were analyzed using data from 1976-1991 Midwinter Aerial Inventories for seven Texas Chenier Plain transects. Transects were also used as a sampling framework for wetland studies; black and white 1:20,000 aerial photos taken during 1964-66 and 1989-90 were analyzed to estimate changes in numbers and areas of wetlands by type. Ten species of ducks selectively (P < 0.10) used Zone A (coastal areas). Numbers of gadwalls (Anas strepera), mallards (A. platyrhynchos), mottled ducks (A. fulvigula), pintails (A. acuta), wigeons (A. americana), and total ducks declined (P < 0.10) during 1976-91. By 1991, numbers of total ducks had declined by 89% from peak populations in the late 1970s. Area of wetlands declined 16% (42,000 ha) between 1964-66 and 1989-90. Major losses occurred in Estuarine Intertidal Emergent (17,000 ha) and Palustrine Emergent Farmed (rice) (50,000 ha) wetlands. Man of these losses were by conversion to open water Palustrine Unconsolidated Bottom (8,000 ha), Lacustrine Limnetic (2,400 ha), and/or diked/impounded/excavated (19,000 ha) wetlands. Losses and degradations appeared primarily in coastal Zone A, and appeared highly associated with declining duck numbers. Management efforts should emphasize halting soil subsidence and saltwater intrusion; and the restoration, enhancement, and/or acquisition of Estuarine and Palustrine Emergent wetlands in Zone A.