Friday, August 10, 2007

PS 72-51: Effects of recreation activities on western snowy plover along the Oregon Coast

Shane D. Latimer, Jesse Schwartz, Troy Rahmig, and Paul Whitney. Jones & Stokes

The Pacific Coast population of western snowy plover (Charadrius alexandrinus nivosus) is federally listed as Threatened. However, populations of this coastal beach-associated shorebird are increasing in Oregon. Some mortality (or “take”) associated with recreational activities does occur in its various life stages (egg, hatchling, fledgling, and adult). We used life tables and simple regression analysis to assess the relationships between restoration efforts, beach recreation, and population performance at seven sites along the Oregon Coast. Analysis of demographic data (2000-2006) showed mortality to be highest (absolute numbers and percentage) for the fledgling and hatchling stages. Egg-to-hatchling survival was the vital rate most strongly correlated with the population’s intrinsic rate of growth (lambda), explaining approximately 89% of the variability seen in lambda. Density of beach access points (number of access points per acre of total habitat) was the strongest indicator of a relationship between recreational activities and egg-to-hatchling survival and appears to be a good overall indicator of the impacts of recreational activities. While it is not possible to determine what specific activities are directly contributing to the overall impacts of recreation on survival, dogs are likely a factor, as 30% of Oregon beach visitors include dogs in their visits. Other impacts, such as the attraction of predators from human-associated food and refuse, and harassment from recreational activities other than dogs, are likely at play. Number of years of predator control was a strong positive indicator of fecundity, suggesting that this restoration activity may be providing some benefits.

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