Does researcher activity impact nest survival of sharp-tailed grouse?

Abstract

Nest survival is a key vital rate of game birds and frequently studied to guide population management. Common scientific protocols are invasive and often involve flushing females from their nests to assess nest contents and status. Biased inference of population dynamics, and thus improper management recommendations, may result if nest survival estimates are affected by researcher activities. We evaluated whether standard nest monitoring protocols for game birds biased estimates of nest survival for sharp-tailed grouse Tympanuchus phasianellus, a common ground-nesting bird in northern grassland ecosystems in the US. We hypothesized that flushing females from nests would negatively affect estimates of daily nest survival and result in biased inferences about population growth regardless of potentially mediating environmental conditions. Our results indicated that cumulative precipitation received during the nesting period had the largest effect on nest survival. Flushing sharp-tailed grouse from nests resulted in reduced nest survival during dry periods, although differences over the entire nesting period were not statistically significant. Downward-biased estimates of nest survival for females that were flushed did not significantly bias estimates of population growth rates. With minimal data loss, we successfully monitored nests of radio-marked females without flushing and recommend that researchers carefully consider potential biases related to research techniques when determining nest monitoring protocols.