A
Chorus Howl
A chorus
of wolves is made up of at least two or three adults. This
chorus changes. It begins with a single howl, which is relatively
simple in structure. After a second or two, a second wolf
joins, followed by one or two more before the rest of the
pack follows virtually en masse.
This
accelerating start makes it possible to pick out the first
three or four individuals but, after that, too many begin
howling at once to count them. Besides, usually only three
have howled before the first wolf is ready to howl again,
so is the fourth wolf howl in the chorus wolf number four
howling for the first time, or wolf number one howling for
the second time?
Once
the whole pack is howling, the sound becomes more and more
modulated, changing pitch rapidly in what seems to be chaotic
disorder. This continues until the chorus winds down a minute
or so later.
Rather
than using howls with a single pure tone, wolves howling
in a chorus use wavering or modulated howls. The rapid changes
in pitch make it difficult to follow one individual's howls
if several others are howling simultaneously.
In
addition, as the sound travels through the environment,
trees, ridges, rock cliffs and valleys reflect and scatter
it. As a result, competing packs hear a very complex mix
of both direct sound and echoes.
If
the howls are modulated rapidly enough, two wolves may sound
like four or more. Indeed, during the Civil War, General
Ulysses S. Grant reported hearing what he took to be a pack
of "not more than 20 wolves" while traveling. A short time
later he reached the pair of wolves that had been making
all the noise!
This
phenomenon, called the Beau Geste Effect, may introduce
enough uncertainty to make size estimates not only unreliable,
but potentially lethal, if a pack underestimates the size
of its rival and approaches.
So
wolves howl to find their companions and keep their neighbors
at bay. Popular imagination has long held that they also
howl at the moon, but there is no evidence that this is
so.
Wolves
may be more active on moonlit nights, when they can see
better, or we may hear them more often on such nights, because
we feel more comfortable tramping about in the light of
a full moon, but a wolf howling at the moon would
be wasting its breath.
by
Fred H. Harrington Professor of Ethology Mount Saint Vincent
University, Nova Scotia
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