Are naïve birds attracted to herbivore-induced plant defences?

Abstract

Arthropod herbivory induces the emission of plant volatiles that can be used by natural enemies of the herbivores to find their prey. Recently it has been shown that insectivorous birds also use these volatiles to locate their prey. Results of a previous study showed that birds with experience in foraging for caterpillars in trees were able to discriminate between caterpillar-infested and uninfested trees, even in the absence of caterpillars or their damage on leaves. Here, we tested whether the attraction to caterpillar-infested trees is exhibited in birds naïve with respect to finding caterpillars on trees. Results show that naïve great tits (Parus major) were not attracted to infested trees, when they could not see the larvae or their feeding damage. Naïve birds cannot discriminate between caterpillar-infested and uninfested trees. Therefore, the attraction to caterpillar-infested trees does not seem to be innate in great tits, and may be acquired through learning.