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12/22/2004
Picky Eaters
This has been both a disturbing and an intriguing week. Last
Wednesday, I posted my column on music and the brain. After
posting my columns, I go immediately to stocksandnews.com to
make sure the column is there and that it fits in the allotted space.
You can appreciate that it came as a shock when, on Friday, I
received an e-mail posted in Asuncion, Paraguay from Editor
Brian Trumbore asking, “Where’s the new column?”
Sure enough, I log on to the Web site and there’s my earlier
column on marijuana staring me in the face! My new column on
music and the brain had disappeared and I had to resurrect it
from my Microsoft Word files and repost it. I’m normally not a
conspiracy type but could it be that someone hacked the site and
deleted the column so as to continue the one on marijuana?
Perhaps it was someone who wanted to use the column to lobby
for passage of legislation legalizing the medical or broader use of
the drug? Or, on the other hand, has Bortrum lost it? Was I
hallucinating when I thought I posted the column? Did any of
my readers see the new column on Wednesday or Thursday? Do
I have any readers? Troubling questions indeed.
Meanwhile, our Editor was having his own problems in South
America. He prides himself on meeting his self-imposed
deadline for filing his Week in Review column very early on
Saturday morning. Frustrated in Asuncion, Paraguay by a lack
of computer technology permitting him to log on to post his
column, he had me post a line stating that the posting would be
delayed until Sunday-Monday, when he would be back in
Santiago, with more modern facilities. Later on Saturday, he
managed to e-mail me a copy of his column and I was able to
post it, not too many hours later than usual. In the column, Brian
details some of his experiences, including the failure of his
luggage to arrive with him in either Santiago or Asuncion.
I was quite impressed that Brian persevered and found a solution
to the communications problem. It reminds me of the ingenuity
shown by Betty, the crow, when confronted with a different kind
of problem. I’ve discussed smart birds before in these columns;
one was the African grey parrot Alex, whose vocabulary and use
of it are astounding. I learned of Betty in an article, “The
Mentality of Crows: Convergent Evolution of Intelligence in
Corvids and Apes” in the December 10 issue of Science. The
authors are Nathan Emery and Nicola Clayton of the University
of Cambridge in the UK. Corvids are a class that includes birds
such as crows, ravens and jays.
Emery and Clayton review recent studies on the various
capabilities of corvids and come up with some conclusions
relating to the evolution of certain cognitive abilities in corvids
and apes alike. I recall a rash promise I made not to discuss
evolution any more this year, so I’ll skip the evolutionary aspects
and just concentrate on some of the capabilities of the corvids.
One well-known capability is the making and using of tools. For
example, New Caledonian crows trim and sculpt twigs to form
hooks to poke into trees and pull out larvae from the trees. These
crows also take a certain kind of leaf and step-cut it to form a
tool that they use to spear prey underneath the leaves on the floor
of the forest.
Betty, the aforementioned crow, is an experienced maker of twig
tools. In the lab, she carries that trait even further. Betty is
presented with the situation where there is food in a bucket and
the bucket is placed in a vertical tube of some sort. There are a
number of metal wires nearby. Betty not only makes hooks out
of the wires but also selects wire of the proper length and
diameter to reach down the tube and pull out the bucket of food.
Tool use is impressive, but more impressive is the ability of
some corvids to travel mentally in time and space. I imagine that
we’ve all seen squirrels gathering and storing acorns and other
nuts for the winter. Corvids also cache food for later use. One
corvid, the Clark’s nutcracker, lives at high elevations and stores
nonperishable pine nuts over a wide area for retrieval during the
long cold months. But the western scrub jay, which lives in a
more moderate climate, is more sophisticated. It stores both
nonperishable and more satisfying perishable foods. The scrub
jay not only remembers where it stored the foods but also knows
how long it takes for the perishable food to spoil and become
inedible.
Peanuts are an example of a nonperishable food that scrub jays
will eat. However, as you might expect, crickets are tastier and
the jays prefer them, given a choice. The Science article cites an
experiment in which scrub jays were allowed to cache both
peanuts and crickets. After they had stored the foods, there was
a period of time during which the jays were given a chance to
find out on their own that crickets had a limited shelf life. Well,
the jays weren’t stupid. When it came time for them to retrieve
their cached food, they realized that too much time had passed
and ignored revisiting the sites where they had stored the tasty
crickets. Instead they settled for the less exciting, but edible
peanuts. The jay knows what, where and when it stored different
types of food and will not go to a perishable food site when its
time is up. Hence, the capacity to mentally travel in time and
space.
I seem to recall a saying “It takes a thief to catch a thief.”
Corvids will not shun the opportunity to snatch a seed or two
from the cache site of another corvid. So, what would you do if
you were a corvid? You would probably hide your food behind a
rock or some other barrier to prevent other corvids from seeing
where you hid the food. Or, if there are other corvids in the area,
you might deliberately make a point of pretending to hide food,
while actually storing something that’s inedible, say a small
stone.
Or, you might hide food in plain sight of a possible thief and
return later to remove the food and store it somewhere else when
the other bird is out of sight or distracted. Hey, you’re not so
clever; corvids do all these things. Lab experiments have shown
that birds that have themselves pilfered items stored by others are
more likely to perform this recaching bit. They apparently learn
from their own thieving experience how to avoid being subjected
to thievery by their fellow corvids.
All this indicates that these corvids are by no means “bird
brained”, but are quite intelligent little animals, comparable in
intelligence to the great apes. That’s the conclusion reached by
Emery and Clayton in their article. When I take my early
morning walks, my presence is often announced by the raucous
warnings of crows overhead that an intruder is in the area. I’ll
have more respect for them in the future.
Brian Trumbore has suggested I take next week off so all best
wishes for a Merry Christmas and a Happy New Year. See you
in 2005.
Allen F. Bortrum
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