Storks — Family Ciconiidae
Wood Stork Mycteria americana
Once a common, if irregular, postbreeding visitor to San Diego County’s coast, since the 1950s the Wood Stork has become ever scarcer. Nesting attempts by two pairs from 1987 to 1991 had no success. From 1990 to 2003 only one immature Wood Stork arrived in San Diego County. In 1986 a pair adopted the Wild Animal Park at San Pasqual as its permanent home, and one of these birds lived through 2003 as California’s only resident Wood Stork.
Migration: In the first half of the 20th century, Wood Storks were recorded all along San Diego County’s coast and on ponds and lakes in the coastal lowland. Sightings at lakes Cuyamaca (M20) and Henshaw (G17) demonstrate that the birds arrived overland from the head of the Gulf of California, as they do at the Salton Sea (Abbott 1935, AB 40:158, 1986). The maximum numbers known are 500 at Agua Hedionda Lagoon (I6) 1–14 August 1938 (Abbott 1938) and 300 at Buena Vista Lagoon (H5/H6) July–August 1953 (Rechnitzer 1954). Dates range primarily from “late May” (1930, 14 in Mission Valley, R8/R9, Abbott 1931) to 9 November (1981, near Oceanside, H5, T. Meixner, AB 36:217, 1982). Records at other times of year are of birds that failed to depart after the customary season.
An immature at Los Peñasquitos Lagoon (N7) 8 July–15 September 2000 (C. DeWitt, J. O. Zimmer, NAB 54:422, 2000, 55:102, 2001) was the first Wood Stork to arrive in San Diego County for at least 10 years.
Winter: A few Wood Storks have straggled through the winter in the coastal lowland. Up to two seen around northwestern San Diego County 1980–87 may have been the same pair that ultimately settled among the captive wading birds and mixed heron colony in the Heart of Africa exhibit at the Wild Animal Park (J12). They were seen here on six of seven Escondido Christmas bird counts January 1987–January 1994. Subsequently only a single bird remained, surviving through 2003.
Breeding distribution: When the Wood Stork was common, there was no suggestion of its breeding in California, so attempts at two sites in the late 1980s and early 1990s were unexpected. At the Dairy Mart pond in the Tijuana River valley (V11), 5 April–3 May 1987, a pair built a nest but fledged no young (B. and I. Mazin, AB 41:487, 1987). Similarly, the pair at the Wild Animal Park nested at least in 1989 and 1991, but no young were ever seen (N. Christianson, D. Rimlinger, AB 43:536, 1367, 1989; 45:1160, 1991).
Conservation: At the Salton Sea, the Wood Stork’s decline has been reflected just as dramatically, if more recently, as in San Diego County (Patten et al. 2003). Bones of four Wood Storks excavated from the trash pit of the stagecoach station at Carrizo Marsh in the Anza–Borrego Desert (O29), dating from 1857 to 1861, demonstrate that the species was once even more widespread than attested by the written record (S. Arter). The stork is now rare in Sonora as well, where the former probable nesting site has been abandoned (Russell and Monson 1998). The Wood Stork has been listed as an endangered species in the United States since 1984, on the basis of a population decline and nesting failures in the Southeast.