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Diverse diet makes caterpillars more likely target for birds

 Diverse diet makes caterpillars more likely target for birds
Caterpillars that feed on a variety of plant species are more likely to get eaten by birds because they lack specialized camouflage, a new study concludes. The tiger swallowtail (Papilio glaucus) pictured here feeds only on black cherry (Prunus serotina). (Michael Singer / Wesleyan University)

Just as the nail that sticks out gets hammered down, the caterpillar that stands out from its leafy environment is more likely to be eaten.

In a study published online Monday in the journal PNAS, scientists at UC Irvine and Wesleyan University concluded that caterpillars who ate more than two species of plants were more likely to wind up as dinner -- a phenomena that had far reaching effects on forest vegetation.

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Butterfly larvae employ a variety of clever tricks to avoid being spotted and eaten by birds. Some sport bright colors or exude noxious odors that warn predators that they might be toxic. Others use camouflage to blend in with their surroundings.

It turns out, according to lead study author Michael Singer, an associate professor of biology at Wesleyan, that the caterpillars who are best at tricking predators are those that specialize in eating just one or two types of plants.

After studying 41 species of forest caterpillars in central Connecticut for four years, Singer and his colleagues found that caterpillars who did not specialize in eating one or two plants had more to eat, but were also more likely to get eaten themselves.

As a result, specialist caterpillars inflicted more damage to their preferred plants, while predatory birds helped to protect those plants that were munched by the diverse-diet caterpillars.

"This study shows the far-reaching effects of herbivore dietary specialization," study authors wrote.

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