Nest Predation Deviates from Nest Predator Abundance in an Ecologically Trapped Bird

Area of Science:

• Ecology
• Conservation Biology
• Behavioral Ecology

Background:

• Ecological traps occur when animals prefer low-quality habitats, leading to reduced survival or reproduction.
• In birds, this is often linked to higher nest predator abundance in preferred habitats.
• However, nest predation rates may not always correlate with predator abundance.

Purpose of the Study:

• To investigate the causes of maladaptive habitat selection in the Lanius collurio, a farmland bird expanding into plantation forests.
• To determine if higher nest predator abundance or a decoupling of predator abundance and predation risk explains lower reproductive success in preferred forest habitats.
• To test the hypothesis that parent bird behavior influences nest predation rates.

Main Methods:

• Comparing nest predation rates and nest predator abundance between forest and farmland habitats.
• Using artificial nests to differentiate between predator abundance and actual predation risk.
• Assessing nest concealment and parent bird behavior during simulated predator intrusions.

Main Results:

• Nest predation caused over 90% of brood failures.
• Nest predator abundance was higher in farmland, but nest predation was higher in forest habitats.
• Lower nest concealment in forest habitats, potentially due to parent bird facilitation of nest disclosure, explained higher predation rates.

Conclusions:

• A decoupling between nest predator abundance and nest predation risk can create ecological traps.
• Parent bird behavior, specifically nest concealment, plays a crucial role in mediating predation risk.
• Conservation strategies in human-modified landscapes should consider behavioral factors influencing habitat selection and reproductive success.