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Angler activity during the waterfowl breeding period can cause a serious decline in breeding waterfowl, in one study a 90% decrease over 10 years. One angler may prevent duck territories or selecting nest sites when the area of open water is less than 1 ha, but disturbance is less of a problem on larger waters. Intensive angling resulted in only 20% of the expected number of waterfowl nests, and nests were restricted to areas inaccessible to anglers. Breeding success is also much lower in areas with anglers because of clutch losses to crows (Corvus sp.) and black-billed magpies (Pica pica); the same is true for boating. Also the motor boat's bow wave tips over exposed nests. Hunters who shoot out nests of crows and black-billed magpies in May to reduce predation of these birds on waterfowl nests have an effect opposite that intended, for flocks of non-breeding crows entering the empty territories. Instead of legislatively creating vitally needed reserves for molting birds, pressure from recreational activities increases in existent sanctuaries. Extensive hunting August-September) prevents an influx of ducks and greatly reduce ecological efficiency of waterfowl in wetland ecosystems to eat vegetation produced and prevent formation of anaerobic muds. The author suggests restrictions for angling and establishment of molting places, and that certain wetlands should be off-limits to duck shooting or boating until studies are made.