Date of this Version
Surveillance of Nesting Birds, Studies In Avian Biology, No.43 pp. 173-182.
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 thirteen-lined ground squirrel (Ictidomys tridecemlineatus) were the most common nest predators documented on videotape, along with mouse (Peromyscus spp.), vole (Microtus spp.), deer (Odocoileus spp.), striped skunk (Mephitis mephitis), coyote (Canis latrans), Black-billed Magpie (Pica hudsonia) , Western Meadowlark (Sturnella neglecta), and gartersnake (Thamnophis spp.). Most predation events occurred during the nestling stage and primarily during the day, potentially due to the increased activity of adults feeding young and of the nestlings begging for food. The diverse predator communities documented destroying grassland songbird nests presents many challenges for land managers attempting to increase reproductive success of Sprague's Pipits and other priority grassland birds.