Data from: Crying wolf to a predator: deceptive vocal mimicry by a bird protecting young

Animals often mimic dangerous or toxic species to deter predators;
however, mimicry of such species may not always be possible and mimicry of
benign species seems unlikely to confer anti-predator benefits. We reveal
a system in which a bird mimics the alarm calls of harmless species to
fool a predator 40 times its size and protect its offspring against
attack. Our experiments revealed that brown thornbills (Acanthiza pusilla)
mimic a chorus of other species' aerial alarm calls, a cue of an
Accipiter hawk in flight, when predators attack their nest. The absence of
any flying predators in this context implies that these alarms convey
deceptive information about the type of danger present. Experiments on the
primary nest predators of thornbills, pied currawongs (Strepera
graculina), revealed that the predators treat these alarms as if they
themselves are threatened by flying hawks, either by scanning the sky for
danger or fleeing, confirming a deceptive function. In turn, these
distractions delay attack and provide thornbill nestlings with an
opportunity to escape. This sophisticated defence strategy exploits the
complex web of interactions among multiple species across several trophic
levels, and in particular exploits a predator's ability to eavesdrop
on and respond appropriately to heterospecific alarm calls. Our findings
demonstrate that prey can fool predators by deceptively mimicking alarm
calls of harmless species, suggesting that defensive mimicry could be more
widespread because of indirect effects on predators within a web of
eavesdropping.