FIELD NOTES LOCATION: Alcatraz Island, S.F. Bay, Calif. Doug Bell WEATHER: Clear sunny. High winds. DATE: MAY 12, 1985 TIME: 12:00 - 1640 Measuring and weighing eggs of Western Gull (Larus occidentalis). Cistern Area: nearly all nests in this area have at least one egg, and up to 3 eggs. Birds hanging very close to nests. Some make mild passes at me when I approach their nests. Especially the birds nesting on the walkway leading up to the cistern - this pair seems particularly vehement. In all, the Gulls seem relatively calm. I could be checking one nest while a gull 4 yards away would resettle on its eggs. Most birds give the mup-mup-mup call when I disturb their nests. Industry Building: checked and measured eggs. Nests had from 0-3 eggs. Behavior of gulls same as for on the Cistern. Both cistern and IB colonies are quite close to one another. The cistern is on a northerly bluff, about 3 yards higher than the Industry Building roof and just east of the I.B., about a 2 yard gap separates the I.B. from the Cistern bluff. While I was checking nests I noticed one nest had apparently come loose and was slowly skidding as a pile of weeds across the IB roof. One egg was in it. Replaced nest to original (?) spot and anchored it down with rocks.