Many vocal species eavesdrop heterospecific alarm calls. However, few studies have revealed heterospecific eavesdropping by non-vocal animals. Most species of lizards, except for Gekkota, do not vocalize, but neurophysiological studies have revealed that most lizard groups possess well-developed ears. We focused on predator detection by auditory information and hypothesized that non-vocal lizards have the ability to eavesdrop on heterospecific alarm calls, so as mammals and birds. To examine this hypothesis we utilized three malagasy lizards: the Madagascan giant day gecko, Phelsuma kochi, the Madagascan spiny-tailed iguana, Oplurus cuvieri, and a wide-tailed zonosaur, Zonosaurus laticaudatus. All of them are diurnal, non-vocal or nearly non-vocal lizards with well-developed ears. We experimentally tested whether these lizards discriminate alarm calls of a syntopic passerine bird, Terpsiphone mutata, from its songs. We played back alarm calls and songs of the bird to wild lizards and recorded their responses with a video camcorder. The analyses of the video records showed that P. kochi changed its body color quicker and darker, O. cuvieri exhibited vigilance behaviors more frequently, and Z. laticaudatus stopped foraging longer, in response to the alarm calls than the songs. These results demonstrate that the three lizard species have the ability to discriminate the avian alarm calls from the songs. This indicates that non-vocal lizards have the ability to eavesdrop on heterospecific alarm calls. Our results suggest the possibility that eavesdropping on heterospecific auditory information may be a widespread phenomenon in lizards.