The Effect of Habitat Edges on Nest Survival of Sprague's Pipits

We explored the relationship between Sprague's Pipit (Anthus spragueii) nest (n = 125) survival and the distance from their nests to grassland edge and other linear features on Bowdoin National Wildlife Refuge in north-central Montana from 1997 to 2007. Specifically, we studied the effect of distance to roads (secondary paved road and tertiary improved and unimproved dirt roads), an agriculture field, an active railroad right-of-way, and lacustrine shoreline on nest daily survival rate (DSR). The overall DSR was 0.95 +/- 0.0057 (SE) with a 95% confidence interval of 0.94-0.96. We considered how models with distance thresholds (within 50, 100, 200, or 300 m) affected DSR while controlling for important covariates. None of the distance models improved the model over the minimum AIC(c) model containing only non-distance covariates. There was no support for distance to any of the edges, including roads, having an effect on DSR relative to the minimum AIC(c) model that contained three non-distance covariates. Received 7 September 2011. Accepted 23 December 2011.