Identification of Sprague's Pipit Nest Predators

Nest predation is the primary factor influencing grassland songbird reproductive success. Understanding factors driving spatial and temporal variation in nest survival requires that we identify the primary nest predators and factors influencing predator abundance and behavior. Predation events are rarely witnessed, and the identification of nest predators is inferred, often incorrectly, from nest remains or observations of potential predators. We used video photography to identify predators of Sprague's Pipit (Anthus spragueii) nests in Saskatchewan and Montana. We monitored 60 nests in Saskatchewan and 11 nests in Montana and documented at least ten different species preying upon eggs and nestlings. Northern Harrier (Circus cyaneus) and thirteenlined ground squirrel (Ictidomys tridecemlineatus) were the most common nest predators documented on videotape, along with mouse rassland species experience higher rates of nest predation than birds nesting in forest and wetland habitats (Martin 1993). Although nest success can be highly variable, some studies show predation rates for grassland songbird nests to be as high as 50-70% M.