Predator-specific mortality of sage-grouse nests based on predator DNA on eggshells

Area of Science:

• Wildlife Ecology
• Conservation Biology
• Molecular Ecology

Background:

• Greater sage-grouse populations are declining across their range.
• Anthropogenic land use, particularly nest predation, is a proposed driver of these declines.
• Identifying specific nest predators is crucial for understanding sage-grouse population dynamics.

Purpose of the Study:

• To test the cattle avoidance hypothesis regarding sage-grouse nest predation.
• To identify the specific predator species of sage-grouse nests using genetic methods.
• To evaluate the influence of habitat characteristics and cattle grazing on predator-specific nest predation.

Main Methods:

• Collected predator DNA from eggshells of predated nests.
• Utilized genetic methods to identify nest predator species.
• Deployed artificial nests with trail cameras to validate genetic methods.
• Assessed the impact of habitat variables (sagebrush cover, distance to water, temperature) and grazing on predation probability.

Main Results:

• Genetic methods accurately identified predators found via trail cameras (94% concordance).
• Nest predators were detected at 67% of predated sage-grouse nests, primarily coyotes and corvids.
• Cattle grazing intensity did not influence predation probability by coyotes or corvids.
• Sagebrush canopy cover negatively associated with coyote predation; distance to water positively associated with corvid predation; temperature negatively associated with both.

Conclusions:

• Cattle grazing did not appear to influence nest predation by primary predators (coyotes, corvids).
• Habitat factors like sagebrush cover, proximity to water, and temperature play a role in predator-prey interactions at sage-grouse nests.
• Developed and validated a non-invasive genetic method for identifying sage-grouse nest predators, valuable for future conservation and management strategies.