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Wetland types

Prairie potholes

Ecology page 4 of 7

mallard duck swimmingTwelve of the 34 species of North American ducks are common breeders in the Prairie Pothole Region. Potholes are especially important breeding grounds for mallard, gadwall, blue-winged teal, northern shoveler, northern pintail, redhead, and canvasback. Indeed, this area is considered the North American “duck factory” due to the large number of ducks produced. The pothole region is a major migration corridor for geese and other water birds during fall and spring.

Each year the amount of rainfall can significantly change water levels which in turn can cause major shifts in flora and fauna. The ecology of the Prairie Pothole Region is defined by cycles of rain and drought. Droughts may last for years, the most recent one running from 1985 to 1993. Climatic extremes influence the types of life that are found in and around potholes.

In times of drought most basins dry up, only the largest and deepest retain water. Wetland plants cease to grow, but their seeds and root systems do not die. Once the rains do come to the prairie, wetland plants re-emerge and thrive.

The distribution of prairie grasses fluctuates with available moisture. During long periods of drought, shortgrass prairie plants increase, replacing mixed grasses in the west, while mixed grasses encroach on tallgrass prairie in the east. During extended wetter seasons, this trend reverses, and tallgrass and mixed prairie expand their ranges.

Wildlife species have adapted to the drought cycles. Many species of ducks will not breed in the region if water is lacking. But when wetlands are full, these birds have the ability to raise many young in one year. In this way, they are able to increase their populations significantly to make up for the lean water years.
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