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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
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
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.