Caterpillars Feedings on Variety of Plant Species More Vulnerable to Being Devoured by Birds

Caterpillars that feed on a variety of plants are more likely to be picked by the hungry winged predators, a new study reveals.

Researchers at the University of California, Irvine, found that caterpillars dining on a variety of nutritious leaves can elevate their risk of being devoured by a discerning bird compared to the ones that feed on just one or two plant species.

"It's a classic example of risk vs. reward," said Kailen Mooney, associate professor of ecology & evolutionary biology at UC Irvine. "Evolutionarily speaking, a caterpillar must choose between having a broad array of plants to feed upon but facing increased risk of being nabbed by a bird and having a very limited menu but being less exposed to predators."

The researchers, say that a varied died does not allow the caterpillar to camouflage well against a green background, hence, they are picked up easily by birds than the other caterpillars who follow a restricted diet

Apart from this, the researchers also found that this had an effect on the plant species too.  Those plant species eaten by caterpillar that are more vulnerable to birds, the ones with the varied diet, benefit from the birds eating these caterpillars. In contrast, the plant species fed upon by caterpillars better able to hide from birds, the restricted diet ones, do not benefit from the birds.

 In another study done earlier, Mooney showed that for birds who hunt for caterpillars, location matters a lot. Caterpillars who feed on black cherry increase their chances of being eaten by birds by nearly 90 percent. The ability to identify trees is learned by birds and is not genetic. 

"If a caterpillar could feed on nutritious, high-quality tree species and be left alone, this would be the best of all worlds," said Mooney. "Instead, it's faced with a trade-off. Overall, it appears that it's better to feed on poor-quality tree species and have fewer caterpillars around you than to be on a nutritious plant with many others."

The finding appears in online edition of Proceedings of the National Academy of Sciences.