Use of Man-made Ponds by Migrating and Wintering Waterfowl in the Blackland Prairie of Central Texas

Abstract

Texas provides winter habitat for millions of migratory waterfowl every year. Most ducks winter on the playas or Gulf Coast, and research regarding waterfowl use and restoration of these areas is abundant. Waterfowl use of habitats elsewhere in Texas has been sparsely studied. However, evidence suggests that ducks use numerous interior ponds and lakes throughout Texas. Blackland Prairie habitat in central Texas extends east-northeast of the city of San Marcos and contains many small ponds, dugouts and drainage basins. This area is well suited for agricultural land use and pasture grasses, and lies between the playas and Gulf Coast.

I counted ducks on 18 ponds during the fall and winter of 2002 and 2003 to identify the species using central Texas Blackland Prairie habitat during migration and winter. Surface area, distance from each pond to nearest aquatic habitat, distance from each pond to nearest study pond, species richness and visual estimates of human disturbance were measured or estimated for each pond and analyzed against waterfowl abundance in a multiple regression analysis.

I counted 14,632 ducks of 16 species. American wigeons (Anas americana, 36%), gadwalls (Anas strepera, 29%), ring-necked ducks (Aythya collaris, 11 %), northern shovelers (Anas clypeata, 9%) and lesser scaup (Aythya afjinis, 7%) accounted for the majority of observed ducks. Puddle ducks (78%) were more abundant than diving ducks (19%) throughout the study.

Ducks used all 18 ponds at some time during the study. Four ponds accounted for 73% of total ducks. Pond surface area ranged from 0.01 - 12.55 ha and positively correlated with waterfowl abundance (r2 = 0.357, P < 0.05). Surface area correlated negatively with waterfowl density (r2 = -0.285, P < 0.05).

The multiple regression model was significant (R2 = 0.873, P < 0.0001). Species richness, distance to nearest aquatic habitat and disturbance scores were significant I predictors of waterfowl abundance. Distance to nearest aquatic habitat and disturbance scores entered the model negatively, indicating that fewer ducks used isolated, highly disturbed ponds.

Small lakes and ponds in central Texas Blackland Prairie habitat provide adequate habitat for numerous species of ducks during the fall and winter. These ponds are ecologically important to migrating and wintering ducks, and their management potential to benefit waterfowl is substantial.