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 Tex3_$ 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.