March 2021, ScientificAmerican.com 17ANIMAL BEHAVIORWhale Mimics
Australian pilot whales
might copy orca callsSouthern long-finned pilot whales are
marine mammals with a lot to say—and
they may use vocalizations to outsmart
a deadly foe.
Cetaceans such as whales, dolphins
and porpoises communicate through
sound to find food and mates, to navigate
and to interact socially. Their vocalizations
vary between species and within commu-
nities. The animals can mimic artificial
noise such as sonar, but nobody had previ-
ously recorded them matching other ceta-
ceans’ sounds. A new study, however,
found overlap in the cetacean sound book.
Researchers listened to 2,028 vocaliza-
tions of long-finned pilot whales off the
coast of Australia, the first time sounds
from the species in this region have been
comprehensively described. They weresurprised to hear 19 instances of vocaliza-
tions that resembled those of orcas—the
whales’ oceanic rivals. “We found some
calls that are, to the human ear, identical to
the killer whale calls in the same area,”
says Christine Erbe, director of the Center
for Marine Science and Technology at
Curtin University in Perth and co-author of
the study, published in Scientific Reports.
Pilot whales and orcas, the two largest
species of delphinid, are often seen in the
same environments and are similar sizes, and
both live in social groups with strong cohe-
sion, says Charlotte Curé, a bioacoustics
researcher at CEREMA Lab in France, who
was not involved in the study. Orcas com-
pete for food with long-finned pilot whales
and are potentially their predators.
Evidence from orca stomachs shows
they do occasionally eat pilot whales. But
pilot whales can mob and chase orcas away,
the only cetaceans seen defending them-
selves from the apex predator in this way.
Mimicry could serve as an additional
defense: “One hypothesis is that if they
use similar sounds, they may not be recog-nized as prey,” Erbe says. Pilot whales
scavenging or eating orcas’ food remnants
might go unnoticed if they use orca like
calls. “This is all underwater, where light
travels really poorly,” she adds. “So these
animals rely on sound for detecting their
prey and predators and for navigating.”
Long-finned pilot whales have shown an
ability to distinguish between orca calls
with different meanings; Curé suggests
that instead of tricking orcas, the callers
could instead be demonstrating a new
orca sound to other group members.
Additional work would confirm wheth-
er mimicry is actually occurring. Research-
ers could pair their listening data with direct
observations of the animals’ interactions
in the wild or perhaps even play orca
sounds and watch the whales’ reactions.
But if a future experiment used preda-
tory sounds, it would need to be done very
carefully. “A reaction to a predator can be
very strong,” Curé says. “In some protect-
ed areas, you are not allowed to do more
than two predatory playbacks per year.”
— Doris Elín Urrutia
© 2021 Scientific AmericanANIMAL BEHAVIORWhale Mimics
Australian pilot whales
might copy orca callsSouthern long-finned pilot whales are
marine mammals with a lot to say—and
they may use vocalizations to outsmart
a deadly foe.
Cetaceans such as whales, dolphins
and porpoises communicate through
sound to find food and mates, to navigate
and to interact socially. Their vocalizations
vary between species and within commu-
nities. The animals can mimic artificial
noise such as sonar, but nobody had previ-
ously recorded them matching other ceta-
ceans’ sounds. A new study, however,
found overlap in the cetacean sound book.
Researchers listened to 2,028 vocaliza-
tions of long-finned pilot whales off the
coast of Australia, the first time sounds
from the species in this region have been
comprehensively described. They weresurprised to hear 19 instances of vocaliza-
tions that resembled those of orcas—the
whales’ oceanic rivals. “We found some
calls that are, to the human ear, identical to
the killer whale calls in the same area,”
says Christine Erbe, director of the Center
for Marine Science and Technology at
Curtin University in Perth and co-author of
the study, published in Scientific Reports.
Pilot whales and orcas, the two largest
species of delphinid, are often seen in the
same environments and are similar sizes, and
both live in social groups with strong cohe-
sion, says Charlotte Curé, a bioacoustics
researcher at CEREMA Lab in France, who
was not involved in the study. Orcas com-
pete for food with long-finned pilot whales
and are potentially their predators.
Evidence from orca stomachs shows
they do occasionally eat pilot whales. But
pilot whales can mob and chase orcas away,
the only cetaceans seen defending them-
selves from the apex predator in this way.
Mimicry could serve as an additional
defense: “One hypothesis is that if they
use similar sounds, they may not be recog-nized as prey,” Erbe says. Pilot whales
scavenging or eating orcas’ food remnants
might go unnoticed if they use orca like
calls. “This is all underwater, where light
travels really poorly,” she adds. “So these
animals rely on sound for detecting their
prey and predators and for navigating.”
Long-finned pilot whales have shown an
ability to distinguish between orca calls
with different meanings; Curé suggests
that instead of tricking orcas, the callers
could instead be demonstrating a new
orca sound to other group members.
Additional work would confirm wheth-
er mimicry is actually occurring. Research-
ers could pair their listening data with direct
observations of the animals’ interactions
in the wild or perhaps even play orca
sounds and watch the whales’ reactions.
But if a future experiment used preda-
tory sounds, it would need to be done very
carefully. “A reaction to a predator can be
very strong,” Curé says. “In some protect-
ed areas, you are not allowed to do more
than two predatory playbacks per year.”
— Doris Elín Urrutiasad0321Adva3p.indd 17Untitled-2 1 1/21/21 11:15 AM1/20/21 7:38 PM