Data from: Causes and consequences of avian within-season dispersal decisions in a dynamic grassland environment

Understanding the causes and consequences of dispersal is key to identifying selective pressures underlying species-level variation in biogeography, metapopulation dynamics and adaptive capacity. We tested the hypotheses that nest predation and/or brood parasitism avoidance drive breeding dispersal decisions and that dispersal functions to reduce subsequent reproductive failure in grasshopper sparrows, Ammodramus savannarum, breeding in eastern Kansas, U.S.A. Over 2 years, we monitored the fate of 222 nests and the movements of 144 parents. We established the spatiotemporal patterns of nest success among all nests, then related nest predation and parasitism to subsequent dispersal behaviour and reproductive success. Birds were more likely to disperse following nest predation, but decisions were unaffected by parasitism. Dispersers experienced higher chances of subsequent nest survival than did site-faithful individuals. Although second nests were parasitized less often than were first nests, dispersers did not experience substantially lower parasitism than did site-faithful individuals, suggesting that the challenges of predation and brood parasitism may be solved in different ways. This study represents one of few tests of alternative hypotheses explaining dispersal decisions of songbirds within seasons and represents a rare case study of the consequences of breeding dispersal on subsequent reproductive success. Our results suggest that differences in dispersal tendencies may result from variation in risk-response thresholds rather than alternative causal drivers.WilliamsandBoyle_AnimalBehavior_DryadData from: Williams,EJ, Boyle WA, Causes and consequences of avian within-season dispersal decisions in a dynamic grassland environment, Animal Behavior. Files contain data and R code used to complete analyses described in the manuscript. Note: File folders and files are organized by how they are described in the Analyses section of the manuscript.Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: DEB-021821