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1996 California Gull Research Resultsby Dave Shuford In 1996, Point Reyes Bird Observatory conducted its fourteenth year of research on the ecology and reproductive success of California gulls nesting on islands at Mono Lake. As some of our pop music icons have commented, "What a long strange trip it's been." While the size of the nesting population in 1996 was close to that in most previous years, reproductive success of the gulls, measured by the number of chicks raised to fledging, was the second lowest since our studies began. Combining our data with that from the Paoha Islets, kindly provided by Dr. Joseph R. Jehl, Jr., we estimated a lakewide breeding population of about 47,500 adult gulls. Of these, 82% occupied the Negit Islets and 18% the Paoha Islets. The fledging rate on the Negit Islets was 0.40 chicks per nest, and the estimated number of chicks fledged from all of the lake's nesting islands was 9,196 young. The reasons for the low reproductive success in 1996 are unknown. Although the lake level continued to rise and cover the landbridge, gulls began to recolonize only one of three re-isolated islets. A coyote was found on Negit Island in July and on Twain Islet in August, at a lake level 6.5 feet higher than when coyotes first reached Twain in 1982. As the lake rises in the future, the proportion of gulls nesting on the Paoha Islets should decrease and likewise increase on the Negit Islets and Negit Island. Future research will be necessary to document the length of time needed for the gulls to fully recolonize islets abandoned after coyote predation. We are extremely grateful to all those who have volunteered to collect data on the nesting islands, provided logistical help on the mainland, or supplied financial support for our research. Dave Shuford is an expert on Mono's gull population and a longtime Mono Basin researcher. Under his direction, the gull research program continues in 1997--see page 14 to participate.
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