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Impact of Red Fox Predation on the Sex Ratio of Prairie Mallards

Settlement of the Prairie


Trappers and explorers were active throughout the prairies of central North America in the early 1800's but for many years they had little overall effect on most wildlife species. As their numbers increased, however, so did their impact on wildlife populations. The most significant changes affecting wildlife accompanied settlement, which in North Dakota began in the early 1870's in the Red River Valley and spread westward with the railroad (Robinson 1966). The number of immigrants to North Dakota increased from 16,000 in 1878 to 191,000 by 1890 (Robinson 1966). The population further increased to 637,000 by 1915, when there were about as many people in the State as there are today. The activities of these early settlers drastically affected the ecology of the region.

The settlement of North Dakota was agriculturally motivated; people spread out in farms and small towns over the largely treeless landscape. By about 1915, the human population was more widely dispersed and evenly distributed than at any other time before or after. The activities of the settlers were visible on nearly every square mile of the fertile pothole region. Most of the tillable land was plowed and much of the remainder was fenced-- the prairie was tamed (Fig. 10). The land, however, could not sustain these early homesteads and shortly thereafter an outmigration from the farms and small towns began. The large number of small farms present at the close of the settlement period is still evident in the multitude of abandoned buildings that dot the prairie. Similar trends occurred throughout the pothole region of Canada (Bird 1961; Kiel et al. 1972).

Man's influence on native wildlife was often dramatic. Very early in the settlement period, for example, bison (Bison bison), whose numbers were once thought to be inexhaustible, were slaughtered by the tens of thousands and nearly exterminated (Bailey 1926). Pronounced changes also occurred among many predator populations because, except in limited areas of rough terrain, species were forced to live in close proximity to man. Some predators that competed with man, such as the gray wolf (Canis lupus) and coyote, were pursued relentlessly. These and other predators, because of a booming fur market, became a source of income and recreation for some residents.

Settlement greatly altered the habitats used by mallards. Many wetlands were drained (Pospahala et al.1974) and much of the upland, where most mallards nest, was annually cultivated or heavily grazed (Kiel et al. 1972). These activities have continued and intensified over the years. Many mallards now nest in croplands that are cultivated, haylands that are mowed, or small, odd areas that are visited regularly by predators (Sowls 1955; Milonski 1958; Higgins and Kantrud 1973; Duebbert and Kantrud 1974). Duck nest destruction rates in many prairie areas now average 70% or greater (Miller 1971). Hens that lose their nests compensate for the losses by renesting, but in so doing expose themselves repeatedly to predators. Hens are thought to be the most vulnerable to foxes when they are nesting (Sergeant 1972). Because of these factors it is likely that mallards suffer greater hen losses now than during pristine times.


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