Fifty Years of American White Pelican Breeding at Stum Lake, British Columbia

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Abstract
The only breeding colony of the American White Pelican (Pelecanus erythrorhynchos) in British Columbia is located at Stum Lake. The species in British Columbia. is designated “Endangered” and it is also included on the provincial “Red List.” As such, the Stum Lake colony has been monitored regularly since 1994, and older records of nest counts and pre-fledgling numbers date back as far as 1953. A marking program for pre-fledging American White Pelicans was conducted from 1968 to 1993. During recent surveys, censuses of nest depressions were obtained late in the breeding season; pre-fledged young were also enumerated. Based on nest counts, numbers at Stum Lake declined in the 1960s and remained more or less stationary throughout the 1970s and early 1980s. In the late 1980s and early 1990s, the number of nesting pairs increased dramatically; and in the past decade, numbers of breeding birds at Stum Lake has stabilized at the highest since monitoring began (1953). The mean number of pre-fledged young also shows an increasing trend from 1963 through 2002. The mean productivity at the breeding colony, however, was highest in the decade showing the largest growth, from 1983 to 1992; but it decreased in the past decade as total numbers of breeding birds continued to increase. The mean productivity of the breeding colony since monitoring began has been 0.62 ± 0.37 young nest-1, with annual rates varying from nil to 1.48 young nest per nest. Four breeding failures have been documented since 1960. The majority of the returns from the marking program were from west of the Continental Divide in British Columbia, Washington, California, Oregon, Idaho and Mexico.