Evaluations of Duck Habitat and Estimation of Duck Population Sizes with a Remote-Sensing-Based System
Figures 7-10
Fig. 7. Density of ponds by landownership class during 1987-90 in the prairie pothole region of the United States, based on aerial videography. Landownership classes include easements (easement) where the U.S. Fish and Wildlife Service has easements on wetlands to prevent draining, filling, or leveling; land owned by the U.S. Fish and Wildlife Service (service); privately owned land (Private); and all landownerships combined (all). Error bars = 1 standard error.
Fig. 8. Area of ponds per km² by landownership class, during 1987-90 in the prairie pothole region of the United States, based on aerial videography. Landownership classes include easements (easement) where the U.S. Fish and Wildlife Service has easements on wetlands to prevent draining, filling, or leveling; land owned by the U.S. Fish and Wildlife Service (service); privately owned land (private); and all landownerships combined (All). Error bars = 1 standard error.
Fig. 9. Average size of ponds by landownership class during 1987-90 in the prairie pothole region of the United States, based on aerial videography. Landownership classes include easements (easement) where the U.S. Fish and Wildlife Service has easements on wetlands to prevent draining, filling, or leveling; land owned by the U.S. Fish and Wildlife Service (service); privately owned land (private); and all landownerships combined(all). 1987-90.
Fig. 10. Average density of breeding ducks (Anatinae) by landownership class during 1987-90 in the prairie pothole region of the United States, based on model projections from aerial videography and ground counts. Duck species include mallards (Anas platyrhynchos), gadwalls (Anas strepera), American wigeons (Anas americana), green-winged teals (Anas crecca), blue-winged teals (Anas discors), northern shovelers (Anas clypeata), northern pintails (Anas acuta), wood ducks (Aix sponsa), redheads (Aythya americana), canvasbacks (Aythya valisnneria), lesser scaups (Aythya affinis), ring-necked ducks (Aythya collards), and ruddy ducks (Oxyura jamaicensis).
