Northern Prairie Wildlife Research Center
Fifty major breeding species (those with a frequency of 10 percent or more on 130 randomly selected quarter-section sample units) comprised about 91 percent of the total breeding bird population in North Dakota. The statewide frequencies of occurrence for six species exceeded 60 percent. These listed in decreasing order of frequency were: Western Meadowlark, Horned Lark, Brown-headed Cowbird, Red-winged Blackbird, Savannah Sparrow, and Mallard. In contrast, the six most plentiful species in decreasing numerical order were: Horned Lark, Chestnut-collared Longspur, Red-winged Blackbird, Western Meadowlark, Lark Bunting, and Savannah Sparrow. Estimated populations of these six species ranged from 2,726,000 to 1,140,000 pairs, and collectively, they comprised 45 percent of the total breeding bird population.
The ecological affinities of the fifty major species differed considerably. Eleven species typical of grasslands comprised 46 percent of the total statewide breeding population, 17 species typical of wetlands comprised 23.3 percent, 14 species characteristic of edge situations (combination of wooded or brushy habitats and open fields or grassland) comprised 14.5 percent, and 8 species that inhabit brushy thickets comprised 6.8 percent. Of the 12 predominant species with populations ranging from 641,000 pairs to 2,730,000 pairs, 6 -- the Horned Lark, Chestnut-collared Longspur, Western Meadowlark, Lark Bunting, Savannah Sparrow, and Grasshopper Sparrow -- are typical of grasslands; 3 -- the Red-winged Blackbird, American Coot, and Blue-winged Teal -- are typical of wetlands; 2 -- the Brown-headed Cowbird and Mourning Dove -- are characteristic of edge situations; and 1 -- the Clay-colored Sparrow -- inhabits brushy thickets.
The characteristic birds of other habitat types in North Dakota are generally of less importance. Many of the extensive, uniform cropland fields in the state are largely devoid of breeding birds, except for the ever present populations of Horned Larks, and very limited numbers of a few other species, particularly those characteristic of edge situations. As might be expected, breeding birds typical of the restricted woodland tracts in the state are of little numerical importance. The same is also true of most of the familiar, commonplace edge species that are associated with lawns, gardens, trees, and shrubbery of farmyards and town residential districts. In general these birds, although often quite common locally, rank far below the more widespread grassland and wetland species in total numbers.
Studies of breeding waterfowl populations also were conducted throughout the Prairie Pothole Region of North Dakota during the three-year period, 1967-1969 (Stewart and Kantrud 1974). These populations were found to fluctuate considerably due primarily to yearly variation in frequency, density, and area of basin wetlands with surface water. Average population parameters for total breeding ducks included a frequency of 82 percent on the random quarter-section sample units, and a density of 44.5 pairs per square mile. The average projected population for the entire region was 1,619,000 pairs, including 1,450,000 pairs (89.6 percent) of dabbling ducks (Anatinae), and 169,000 pairs (10.4 percent) of diving ducks (Aythyinae and Oxyurinae). Five primary species of ducks -- the Gadwall, Mallard, Pintail, Blue-winged Teal, and Northern Shoveler -- comprised 83 percent of the total breeding duck population. The Mallard exhibited the highest frequency (65 percent) and the Blue-winged Teal the highest average density (13.9 pairs per square mile).
Certain disparities in proportion of the breeding duck populations occurred in the four biotic subregions of the Prairie Pothole Region. Population densities of total ducks and total dabbling ducks were fairly constant on the Northeastern and Southern Drift Plains and Missouri Coteau, but were noticeably lower on the Northwestern Drift Plain. The population density of total diving ducks was markedly higher on the Missouri Coteau than on the other three subregions.
Data concerning the ecological distribution of. breeding waterfowl populations were also analyzed (Stewart and Kantrud 1973). In 1967, about 84 percent of the statewide duck population occurred in the Prairie Pothole Region. Within this region during 1967-1969, seasonal or Class 3 ponds and semi-permanent or Class 4 ponds and lakes (as classified by Stewart and Kantrud 1971) were utilized by about 48 and 27 percent, respectively, of the total breeding ducks. Optimum environmental conditions for breeding dabbling ducks were present during years when large numbers and acreages of seasonal pond basins contained surface water. Semipermanent ponds and lakes were the principal habitats for breeding diving ducks, and were also important to dabbling ducks, particularly during dry years.