Water level fluctuation is probably the most significant environmental factor influencing waterfowl production. The three basic life processes of waterfowl in Canada, breeding, moulting and staging, are all affected by water level changes in the long and short term. The impact of water level fluctuations on breeding success is the most important way in which waterfowl production is influenced. Habitat suitability for waterfowl tends to reflect long-term water level fluctuations while habitat utilization can be affected in the short term by seasonal and annual changes in water level. The importance of magnitude, direction, rate and timing of water level fluctuations in determining waterfowl breeding success is discussed. Although waterfowl have developed a number of adaptations to cope with water level fluctuations, these responses are normally not completely effective and result in some degree of decreased production. Although having a number of negative impacts on waterfowl production, water level fluctuation is essential for the long-term maintenance of wetland productivity.
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