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Sounds courtesy Daniel Mennill:
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The
best
songs, it would seem, are about love. Whether it's a blues singer
lamenting
a lost love, or the sirens luring Odysseus to the shoals, a good song
is
a great way to attract the opposite sex.
This is
not news to songbirds, who
started
mixing
crooning and wooing long before Frank Sinatra lamented that he "didn't
stand a ghost of a chance with you."
Songbirds
perform their vocal gymnastics to mark territory and get noticed by
eligible
females. Many scientists think the quality of the song tells her about
his health -- since only a healthy guy bird could belt out the avian
equivalent
of "Lover Man."
Now we
hear that female black-capped
chickadees do
more than listen closely. When their fellas lose out in a song
competition,
the ladies respond.
But not
with a soothing, "Honey,
maybe you
can't
hit high C-sharp, but you're still number-one. Come kiss my chicken
lips."
No. The
takeaway message for the
ladies is:
"I married
a loser!"
And then
they step outside the nest
for
some quick
action with another guy! In evolutionary terms, that would guarantee
that
at least some of her young get top-notch genes.
This, in short, is the message of a new
study
by
Daniel Mennill and colleagues at Queen's University, Kingston, Ontario.
Mennill, a graduate student, is interested in how animals make
decisions,
and especially how birds communicate during mating. Instead of looking
just at two parties, however, he's checking the network thing -- how,
say,
a third party interprets communication between two others.
He calls
it eavesdropping, since the
females overhear
the "conversations" of others.
Mennill
studied wild-living
black-capped
chickadees
at the Queen's University biological station and identified high- and
low-status
males. As with people, upper-crust chickadees skim off the cream, so to
speak. "At a food source... everybody makes way for the highest ranking
bird," he says.
Male songs during mating season can be
submissive
or aggressive, Mennill says. Aggressive
songs copy the pitch of the other guy's song.
In
contrast, a submissive
song uses a different pitch, giving the first songster some
breathing
room..
During
mating season, Mennill hung
out in
the woods
with a laptop and a speaker. He gathered the birds by playing the
familiar chickadee
call.
When the guys began their mating songs,
Mennill
used software to identify the frequency, and then issued either an
aggressive
or a submissive song from his laptop. Weeks later, after the young were
born, he took blood samples and used genetic techniques to determine
each
kid's biological dad.
The
genetics told the sordid tale,
Mennill
says.
"After a high-ranking guy lost a competition because I matched and
overlapped
his song, his female engaged in extrapair copulations." To Mennill,
this
proves that the females are eavesdropping on the guy-to-guy discussion.
Although
songbirds were once
considered
monogamous
-- they hang out in couples, and all of the young in the nest of a
dominant
male are normally his -- their behavior actually has elements of Beach
Blanket Bingo. Many females do a certain amount of stepping out on
their
mates.
So when
the lady heard her guy
humiliated
by the
computerized song, about half of her future young wound up having a
different
dad, Mennill reports. "She's accustomed to hearing him win every song
contest,
but after hearing him lose, she changes her reproductive strategy."
Indeed,
it took only six
minutes a
day, on two successive days, for the
songs to change the female's mind, says Mennill. Apparently "the kind
of
information available through eavesdropping has a lot of importance
relative
to reproductive strategies."
The
overlapping and matching songs
may have
other
uses, says Mennill. "Most animals, including chickadees, live in
groups,
where many males are singing at the same time. You have to have
capacity
to address one individual if you want to say 'Hey you, I want you out
of
my territory.'"
Moral of
the story: Guys, if you want
to
impress
the ladies, tune up those vocal cords,.
Karaoke,
anyone?
-- David
Tenenbaum
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