Data from: A bee or not a bee: an experimental test of acoustic mimicry by hoverflies

The degree of similarity between Batesian mimics and their models varies
widely and occurs across a range of sensory modalities. We use 3
complementary experimental paradigms to investigate acoustic mimicry in
hoverflies (Diptera: Syrphidae), which mimic stinging Hymenoptera. First,
we analyze sounds made by 13 hoverfly species and 9 Hymenoptera species
with and without simulated predation (“alarm” and “flight” sounds,
respectively). We demonstrate that the bumblebees Bombus terrestris,
Bombus hortorum, and Bombus lucorum and the hoverfly Cheilosia illustrata
exhibit alarm sounds that are significantly different to their respective
flight sounds, and indistinguishable between species. We then demonstrate
that the B. terrestris alarm sound reduces predation on artificial prey by
wild birds, but that the hoverfly mimic alarm sound does not. Finally, we
trained chicks to avoid distasteful food in the presence of different
acoustic stimuli. Overall, the chicks showed no difference in response to
bee and hoverfly stimuli, demonstrating no innate aversion to the Bombus
alarm sound. We therefore conclude that 1) similarity of acoustic signals
exists among Hymenoptera and hoverflies, 2) acoustic aposematic signals
(but not the almost identical mimetic signals) are effective at reducing
predation, and 3) wild birds exhibit learned rather than innate aversion
to certain acoustic stimuli.