While hunting is often considered the major cause of duck mortality, it's predation that's been holding duck numbers back. Upwards to 50 percent of all the hens killed each year are taken by predators, and in previous years 90 percent or more of all duck nests were destroyed by predators. CRP sets aside large blocks of undisturbed grassy cover making nests more difficult for predators to locate. Rodent populations thrive in CRP, which takes some of the pressure off ducks. Prior to CRP, nest success across the region was running a mere six to eight percent, well below the 14 percent necessary just to maintain the population.
Water is the other part of the equation.
Migrating ducks look for certain types of water before establishing a nest. The rains came in late 1993, filling long empty wetlands and allowing duck numbers to begin their meteoric rise. In 1993 the continental duck population was listed at 59 million birds. Today it's claimed to be pushing 100 million. That dramatic jump was made possible by the US Department of Agriculture, which provided CRP, and Mother Nature, who added water.