Thirty-nine years after the last Peregrine Falcon (Falco peregrinus anatum) nest was documented in San Diego County, a pair has bred successfully on the Coronado Bay Bridge. Peregrines originally numbered between 100 and 300 nesting pairs in California with four to six pairs per year in San Diego County (Bond 1946, Cade et al. 1988). Prior to 1948 active nests existed at Point Loma, La Jolla cliffs, San Pasqual, and Morro Hill (collected eggs in the Western Foundation of Vertebrate Zoology), San Onofre (Dixon 1906), Pala and Santa Margarita river estuary (Dixon 1917), Escondido (Sharp 1919), and the nearby Los Coronados Islands (Howell 1910). In the 1950s, however, Peregrine numbers plummeted primarily because of egg shell thinning caused by widespread use of organochlorine pesticides, especially DDT (Hickey 1969, Ratcliffe 1980). The last recorded sign of a breeding Peregrine in San Diego was a single egg collected from a “sea wall” in 1950 (Western Foundation of Vertebrate Zoology). By 1970, the California Peregrine population had been reduced by over 95% to only two known nesting pairs, neither in San Diego (Herman 1971).