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Peregrine Falcon populations declines, as a result of widespread DDT use in the 1950s, occurred first in temperate regions, then later in the northern breeding grounds (White et al. 2002). By 1970, the species was extirpated throughout its range east of the Rockies and south of the boreal forest, and had declined drastically in northern Canada while a smaller decline occurred along the British Columbia coast (White et al. 2002). Since the early 1970s, when DDT was banned, the population has increased dramatically as a result of introductions from captive-bred birds. The Peregrine Falcon is best monitored in Canada through a directed survey that has taken place on the breeding grounds every 5 years between 1970 and 2005. Data from this survey, when adjusted for sites not monitored in the early years of the survey, show an increase from about 133 active sites in 1970 to 652 sites in 2005, an increase of almost 400% (COSEWIC 2007e). Results from the Breeding Bird Survey in Canada are insufficient to calculate a trend. However, the population increase is evident in the continental-level results, which show a large increases in the North American population since the mid-1960s.
Additional information on: Number of active Peregrine Falcon nest sites in Canada from 1970-2005
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Additional information on: Breeding Bird Survey in North America (BBS) - U.S. analyses