Evaluations of Duck Habitat and Estimation of Duck Population Sizes with a Remote-Sensing-Based System

Lewis M. Cowardin, Terry L. Shaffer, and Phillip M. Arnold

U.S. Department of the Interior
National Biological Service
Northern Prairie Science Center
Jamestown, North Dakota 58401

Abstract: During 1987-90, we used high-altitude photography, aerial videography, counts, and models to estimate sizes of breeding populations of dabbling ducks (Anatinae) and duck production and to identify duck habitat on U.S. Fish and Wildlife Service land and easements and on private land in the prairie pothole region of the United States. The study area contained about 3.1 million wetland basins (28,490 km²). Wetland area (ha per km²) was highest on service-owned land; wetland-basin density was greatest on service easements. Temporary and seasonal wetlands were underrepresented and lakes were overrepresented on service-owned land. Seventy-eight percent of all basins were less than 0.41 ha. Cropland dominated private land. Pond density decreased from 4.4/km² in 1987 to 3.4/km² in 1990 and pond area, from 7.2 ha/km² to 2.7 ha/km². The density of the blue-winged teal was greatest (3.4 pairs/km²) and was followed in magnitude by those of the mallard (2.1 pairs/km²), the gadwall (1.8 pairs/km²), the northern pintail (0.8 pairs/km²), and the redhead (0.8 pairs/km²). Duck density was consistently highest on service-owned land. The decline of breeding-population sizes in 1987-90 closely corresponded to losses of pond numbers and pond area. The density of breeding pairs per pond was inversely related to pond density, suggesting that breeding ducks tended to concentrate on the remaining ponds as drought intensified. The production of recruits followed the same pattern as breeding-population sizes. We estimated that 2.5% of the ducklings hatched on service-owned land, which was 1.3% of the study area; 19.6% hatched on service easements, which were 14.2% of the study area; and 77.9% hatched on private land, which was 84.6% of the study area. Various sources of bias and sampling error and improvements to the system are discussed.

Key words: Ducks, wetlands, population, recruitment, management, models, videography, drought.

This resource is based on the following source (Northern Prairie Publication 0925):

Cowardin, Lewis M., Terry L. Shaffer, and Phillip M. Arnold.  1995.  Evaluations 
     of duck habitat and estimation of duck population sizes with a remote-
     sensing-based system.  National Biological Service, Biological Science 
     Report 2.  26pp.

This resource should be cited as:

Cowardin, Lewis M., Terry L. Shaffer, and Phillip M. Arnold.  1995.  Evaluations 
     of duck habitat and estimation of duck population sizes with a remote-
     sensing-based system.  National Biological Service, Biological Science 
     Report 2.  Jamestown, ND: Northern Prairie Wildlife Research Center Online.  
     http://www.npwrc.usgs.gov/resource/birds/duckhab/index.htm
     (Version 16JUL97).

Introduction
Methods
Results and Discussion
- Habitat Base
- Duck Populations and Production
Conclusions and Management Implications
- Wetland and Duck Management
- System Evaluation
Acknowledgments
Cited References

Tables

Table 1. -- Numbers of 10.4-km² plots (n) for evaluating duck (Anatinae) habitat and estimating numbers of ducks and number of plots covered by videography (NV) during 1987-90 in the prairie pothole region of the United States.
Table 2. -- Wetland-basin class definitions based on the water regime of the basin-naming polygon.
Table 3. -- Baseline regression coefficients used for estimating breeding duck (Anatinae) populations on 10.4-km² plots from the area (ha) of individual ponds determined from airborne video in the prairie pothole region of the United States, 1987-90.
Table 4. -- Average brood sizes of surface-feeding ducks (Anatinae), derived by scaling mallard (Anas platyrhynchos) brood size by relative clutch sizes of mallards and other species during a 1987-90 study in the prairie pothole region of the United States.
Table 5. -- Percent of total wetland basins that contained ponds in a study area in North Dakota (Cowardin et al. 1985) and estimates of A during 1977-80 in the prairie pothole region of the United States.
Table 6. -- Land ownership (%) by state in the prairie pothole region of the United States based on 1986 data.
Table 7. -- Estimated number of basins, area of wetland, density of basins, and area of wetland/km² by land-ownership class in the prairie pothole region of Minnesota, North Dakota, South Dakota, and extreme eastern Montana, based on photographs from the early 1980s.
Table 8. -- Estimated area of upland habitats by landownership class in the prairie pothole region of Minnesota, North Dakota, South Dakota, and extreme eastern Montana, based on photographs from the early 1980s.
Table 9. -- Estimates of A, a measure of nesting intensity, by wetland management district and year during 1987-90 in the prairie pothole region of the United States.
Table 10. -- Estimates of average clutch success by species and landownership class during 1987-90 in the prairie pothole region of the United States.

Figures

Figure 1. -- Distribution of 10.4-km² sample plots used to evaluate duck (Anatinae) habitat and population size during 1987-90 in the prairie pothole region of the United States.
Figure 2. -- Regression of number of blue-winged teal, gadwall, northern shoveler, and northern pintail pairs on pond size during 1987-90 in the prairie pothole region of the United States.
Figure 3. -- Hypothetical distribution of duck (Anatinae) habitats and nests on a 10.4-km² plot with two landownerships and two habitats.
Figure 4. -- Numbers of successful nesting attempts by ducks (Anatinae) on a hypothetical 10.4-km² plot with two landownership classes.
Figure 5. -- Cumulative distribution of wetland basins by size and wetland-basin class in the prairie pothole region of the United States, base on photographs from the early 1980s.
Figure 6. -- Distribution of wetland-basin classes by landownership class in the prairie pothole region of the United States, based on photography from the early 1980s.
Figure 7. -- Density of ponds by landownership class during 1987-90 in the prairie pothole region of the United States, based on aerial videography.
Figure 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.
Figure 9. -- Average size of ponds by landownership class during 1987-90 in the prairie pothole region of the United States, based on aerial videography.
Figure 10. -- Average density of breeding ducks (Anatinae) by landownership class during 1987-90 in the prairie pothole region of the United States.
Figure 11. -- Relation of density of blue-winged teal, gadwall, mallard, northern shoveler, and northern pintail pairs to pond size during 1987-90 in the prairie pothole region of the United States
Figure 12. -- Relation of density of blue-winged teal, gadwall, mallard, northern shoveler, and northern pintail pairs to area of ponds during 1987-90 in the prairie pothole region of the United States.
Figure 13. -- Relation between average number of pairs of blue-winged teal, gadwall, mallard, northern shoveler, and northern pintail per pond and pond density during 1987-90 in the prairie pothole region of the United States.
Figure 14. -- Relation between the average number of duck (Anatinae) pairs per km² and year by landownership class during 1987-90 in the prairie pothole region of the United States.
Figure 15. -- Number of produced recruits per km² by blue-winged teal, gadwall, mallard, northern shoveler, and northern pintail during 1987-90 in the prairie pothole region of the United States, based on model projections from aerial videography and ground counts
Figure 16. -- Number of produced recruits per mi² of blue-winged teal, gadwall, mallard, northern shoveler, and northern pintail during 1987-90 in the prairie pothole region of the United States, based on model projections from aerial videography and ground counts.
Figure 17. -- Recruitment rate of five species of dabbling ducks during 1987-90 in the prairie pothole region of the United States, based on model projections from aerial videography and ground counts.
Figure 18. -- Average number of successful nesting attempts per km² by blue-winged teal, gadwall, mallard, northern shoveler, and northern pintail by landownership class in the prairie pothole region of the United States, based on model projections from aerial videography and ground counts

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Evaluations of Duck Habitat and Estimation of Duck Population Sizes with a Remote-Sensing-Based System

Table of Contents

Tables

Figures