Elevated mercury concentrations in failed eggs of Snowy Plovers at Point Reyes National Seashore

摘要

Along the US Pacific Coast the population of Snowy Plovers (Charadrius alexandrinus) has been shrinking. This decline has been attributed to habitat degradation, preda-tion, and human recreational use of beaches. As a result the US Fish and Wildlife Service designated the Pacific Coast population of Snowy Plover as threatened (Page et al., 1995). The beaches of Point Reyes National Seashore provide attractive nesting habitats for the Snowy Plover. The management authority of the National Park Service over these beaches provides the opportunity to implement and assess management strategies that reduce the impact of predation and recreational beach use. Monitoring of plover nesting at Point Reyes by the Point Reyes Bird Observatory and the National Park Service documented that the 2000 breeding season had "more nests than in all the years this beach has been monitored since 1986", yet the clutch hatching rate of 50% was the lowest in the last four years (Ruhlen and Abbott, 2000).