Thirty years ago, many farmers on the Canadian prairies idled their fields every other year. Standing stubble left in these idle fields usually wasn’t tilled for weed control until late May or early June, giving early-nesting pintails an opportunity to hatch a brood. Consequently, during the wet years of the 1970s, large numbers of pintails hatched on idle cropland likely bolstered production on remaining grasslands, enabling pintails to produce enough young to support impressive wintering populations in areas such as California’s Central Valley.
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Unfortunately for pintails, during the past three decades most prairie farmers have shifted to annual cropping schedules where most fields are planted every year. As a result, most pintail nests in crop stubble are now destroyed well before their hatching date when the fields are seeded in early to mid-May. This dramatic shift in farming practices has eliminated nearly 13 million acres of potential pintail nesting habitat that once existed on fallow croplands in Prairie Canada, likely having a devastating impact on the population (see graph).
Beyond the prairies, significant numbers of pintails breed on wetlands associated with vast inland river deltas in the western boreal forest and tundra regions of northern Canada and Alaska. These deltaic wetlands also support large numbers of nonbreeding pintails during drought years on the prairies and during the summer molt. Although development impacts in the north remain relatively light compared to the prairies, the future expansion of logging, mining, and oil and gas development could threaten wetlands used by large numbers of breeding and molting pintails and other waterfowl.
Pintails have also suffered extensive habitat loss on key wintering and migration areas. Of particular importance to pintails and other waterfowl are seasonally flooded wetlands, which contain seeds and invertebrates that are important natural foods for the birds. In the Pacific Flyway’s most important pintail wintering area, the Central Valley of California, more than 95 percent of its original wetlands have been lost, and wintering waterfowl now rely heavily on flooded croplands, especially rice fields, for feeding and resting habitat. But these croplands are now threatened by urban development and water-use conflicts driven by California’s rapidly growing human population. Farther north in the Klamath Basin of northern California and southern Oregon, where the majority of Pacific Flyway pintails gather to feed and rest during the spring migration, remaining wetlands are threatened by chronic water shortages and declining water quality exacerbated by years of severe drought.