1. The year-round movements and nesting activities of snowy plovers that bred on the California coast in the Monterey Bay and Point Reyes areas were closely monitored between 1984 and 1989. 2. About half of 208 females and a quarter of 190 males with histories of one or more complete breeding seasons were absent from focal nesting areas for all or part of at least one breeding season. The incidence of such absences in the population was 41% in females and 16% in males, as estimated from regular nesters at the focal areas. 3. Partial-season absence was far more common than entire-season absence for regular nesters in the focal areas. Presence for partial-seasons was more common than presence for entire seasons for irregular nesters in the focal areas