Related Experiment Video
Updated: Jul 12, 2026
07:34
Probing the Limits of Egg Recognition Using Egg Rejection Experiments Along Phenotypic Gradients
Published on: August 22, 2018
Taste-aversion conditioning of crows to control predation on eggs
Science (New York, N.Y.)
|April 8, 1983
Summary
Crows learned to avoid green-painted eggs after experiencing illness from a nonlethal toxin. This learned aversion extended to all green eggs, even those without the toxin, demonstrating predator learning in wildlife ecology.
Area of Science:
- Behavioral Ecology
- Animal Behavior
- Evolutionary Biology
Background:
- Predator learning plays a crucial role in ecological interactions and the evolution of defensive strategies in prey.
- Understanding how predators form aversions to specific prey cues is essential for ecological research and wildlife management.
Purpose of the Study:
- To investigate if free-ranging crows (Corvus brachyrhynchos) can develop an aversion to a specific visual cue (green-painted eggs) associated with illness.
- To determine if this learned aversion persists even when the cue is present without the negative consequence (toxin).
Main Methods:
- Crows were presented with chicken eggs painted green and containing a nonlethal toxin.
- Subsequent exposure to green eggs (with or without toxin) and unpainted eggs was monitored to assess avoidance behavior.
Main Results:
- Crows successfully learned to avoid green-painted eggs after a single illness-inducing experience.
- The aversion generalized to all green eggs, regardless of the presence of the toxin.
- Crows continued to consume unpainted, non-toxic chicken eggs, indicating a specific learned aversion.
Conclusions:
- Illness-induced aversions in predators can be a significant factor in the evolution of mimicry, such as Batesian mimicry.
- This learned aversion can be a practical tool for wildlife ecologists to manage predator behavior and protect certain prey species.
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