Functional response, seasonal decline and landscape differences in nest predation risk

Area of Science:

• Ecology
• Behavioral Ecology
• Conservation Biology

Background:

• Density-dependent nest predation is crucial for avian reproductive success.
• Previous studies had limitations due to artificial nest densities or lack of predator controls.
• Understanding factors influencing nest predation risk is vital for effective conservation.

Purpose of the Study:

• To investigate density-dependent nest predation risk in artificial nests within natural density ranges.
• To assess the influence of season, landscape type, and predator proximity on nest predation.
• To validate artificial nest predation risk with real nest data from red-backed shrikes (Lanius collurio).

Main Methods:

• Utilized artificial shrub-nests with quail and plasticine eggs in Swedish grasslands.
• Employed a Latin square design to control for predator density variations in time and space.
• Compared predation risk on artificial nests with real nests of red-backed shrikes.

Main Results:

• Corvids were identified as primary predators, showing a functional response to increasing artificial nest density.
• Nest predation risk decreased over the breeding season and varied significantly with landscape type (farmland vs. forest).
• Predation risk was higher closer to corvid nests, and shrikes selected low-risk areas, correlating with their reproductive success.

Conclusions:

• Artificial nest predation risk can serve as a reliable index for spatial and temporal variations.
• Grasslands in forested landscapes present lower predation risk and warrant conservation focus.
• Habitat management considering predator distribution and landscape context is essential for bird conservation.