LIFE & EVOLUTION
Songs may not advertise brainpower
Female birds can’t rely on tunes to discern a male’s smarts
BY SUSAN MILIUS
After some 20 years of work, a scientist is
publicly renouncing his own “beautiful
hypothesis” that male birds’ sexy songs
could indicate the quality of their brains.
Behavioral ecologist Steve Nowicki of
Duke University called birdsong “
unreliable” as a clue for choosy females seeking
a smart mate in a talk on January 4 in
Tampa, Fla., at the annual meeting of the
Society for Integrative and Comparative
Biology. He presented results published
in the March 2018 Animal Behaviour,
plus an unpublished critique based on
male songbirds that failed to score consistently on learning tests.
“This was a beautiful hypothesis that
got beaten up by data,” he says.
Knowing that something about male
singing matters to females, Nowicki
and others previously proposed that the
quality of singing might indicate a bird’s
brainpower. The idea was that, because
songbirds need to learn their songs,
females could select males with the best
brain development by selecting those
singing the most precisely copied songs.
A brainier male might be better at hunting baby food or spotting predators, thus
helping chicks to survive. Or braininess
might signal an indirect benefit, such as
contributing good genes to chicks.
The first evidence for the notion that
birdsong indicates bird smarts came
from Neeltje Boogert of the University
of Exeter in England, whose research
suggested that female zebra finches
preferred smarter males with more complex songs. But subsequent studies have
found evidence both supporting and
contradicting the idea. To try to settle
the matter, Nowicki and collaborators
hand-raised 19 male song sparrows in
the lab, controlling which songs the birds
heard as examples to copy so that it was
clear how well each youngster learned
To judge the birds’ mental capacity
separately from their song learning, the
researchers administered five learning
challenges, such as learning which col-
ored container lids to flip open for food.
We “found a hodgepodge” of results,
Nowicki says. A bird might have done
well on some tests and flubbed others,
and the puzzle-solving results didn’t
match a bird’s song learning ability.
“Maybe they weren’t cognitively good
at stuff because they lived their life in a
cage,” Nowicki wondered. So, he and colleagues turned to wild swamp sparrows.
It’s trickier to judge the precision
of birds’ mimicry in the wild, where
young hear multiple songs to copy. So
a coauthor had a computer sort recordings from the marsh into a few “typical”
song types. The closer a newly musical sparrow’s songs came to the typical
forms, the higher the scientists ranked
the bird’s learning. The team also put the
new singers through the cognitive tests.
Again, the results were a hodgepodge,
Nowicki says, finally beating to pieces
his hypothesis about birdsong.
Songbirds may not have a general “IQ”
in the sense that people use the term,
says Rindy Anderson of Florida Atlantic
University in Davie, who has worked with
Nowicki. Instead, bird intelligence may
be modular, she says, with the birds good
at some mental tasks but not others.
Even if male songbirds don’t betray
their smarts through song, some scientists are testing a different group of birds
to see if females prefer smarter mates.
Among flirting budgerigars, a kind of
parrot, females preferred males that had
learned to perform food-finding tricks
over uneducated males, as reported in
the Jan. 11 Science. A parrot researcher
who wasn’t involved in that study, Tim
Wright of New Mexico State University
in Las Cruces, and a former student are
finishing a paper on a different way of
testing whether budgerigars’ sex appeal
is tied to smarts. “There is evidence out
there and there will be more coming
shortly,” Wright says. s
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