In 1989, the California Fish and Game Commission listed the bank swallow (Riparia riparia) as a threatened bird species in accordance with the California Endangered Species Act. This action was based upon a California Department of Fish and Game (CDFG) petition that documented that the species had declined throughout its range within California, was extirpated from approximately 50% of its historic range (primarily in the southern part of the State), and faced further reduction in populations and habitat due to ongoing bank protection projects of the State Reclamation Board and the U.S. Army Corps of Engineers on the Sacramento River, Feather River, and major tributaries. Sacramento Valley riparian systems provide habitat for over 70% of the remaining population. Research conducted during the bank swallow breeding seasons in 1986 and 1987, followed by annual monitoring established the scientific basis for the petitioned action that recommended listing of the species in 1989. Additional monitoring of the Sacramento River population of bank swallows has documented a serious decline since the 1986 baseline for population estimates. The 1996 breeding population of 5,770 pairs of bank swallows is only 44% of the 1986 estimate of 13,170 pairs. Many colony sites and eroding banks along the Sacramento River continue to be threatened by planned bank protection projects proposed for construction
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