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BIRD PREDATION AS A SELECTIVE AGENT IN A BUTTERFLY POPULATION.
M Deane Bowers1, Irene L Brown2, Darryl Wheye3
1Museum of Comparative Zoology, Harvard University, Cambridge, MA, 02138.
Summary
Birds preyed on checkerspot butterflies (Euphydryas chalcedona), targeting slightly more females. Among males, less red coloration made individuals more vulnerable to bird attacks.
Area of Science:
- Ecology
- Behavioral Ecology
- Predator-Prey Dynamics
Background:
- Predation is a significant factor shaping insect populations.
- Understanding predator selectivity provides insights into prey survival strategies.
- The checkerspot butterfly (Euphydryas chalcedona) is a model organism for ecological studies.
Purpose of the Study:
- To investigate predator selectivity in a checkerspot butterfly population.
- To determine if sex or coloration influences predation risk by birds.
Main Methods:
- Collected detached wings from 309 bird-attacked checkerspot butterflies.
- Photographed a sample of 296 live butterflies for comparison.
- Analyzed sex ratio and forewing coloration of attacked vs. unattacked individuals.
Main Results:
- Birds attacked a slightly higher proportion of females than males.
- Among male checkerspot butterflies, those with less red coloration on their forewings were attacked more frequently.
Conclusions:
- Predation by birds exhibits sex- and color-based selectivity in this checkerspot butterfly population.
- Wing coloration, particularly in males, may serve as a visual cue for predators.
- These findings contribute to understanding the evolutionary pressures driving sexual dimorphism and coloration patterns in insects.
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