Off-road vehicle use partially conflicts with habitat of the western snowy plover ("Charadrius nivosus") which was listed as threatened under the Endangered Species Act (ESA) on March 5, 1993. It is alleged that use by vehicles directly correlates with a decrease in reproductive success. However, western snowy plover nests have increased dramatically from 16 nests in 1993 to a total of 172 nests in 2011. Memorial Day weekend is one of the park's busiest, and occurs during the plover nesting season. Yet, year after year, large numbers of plover nests are found at nesting sites closest to the open vehicle area at Oceano Dunes, suggesting human presence may deter presence of predators, and that plover may receive refuge at these sites. An eight-year summary of western snowy plover reproduction on California State Park lands depicts the breeding success at Oceano Dunes which is particularly stark compared to very low breeding numbers elsewhere in the state.