After writing about black holes, as I did last week, I like to return
to more down-to-earth subjects, animal behavior being a favorite.
I’ve mentioned seeing a very healthy looking red fox pass
through our backyard recently, the first fox I’d seen in our town.
Last Sunday our Lamb creator, Harry Trumbore, dropped by and
told us of an intriguing incident with a fox in his backyard.
His backyard borders on a wooded area harboring deer and other
creatures, notably wild turkeys. In past years, the turkeys were a
novelty and would eat seeds that dropped from a generously
supplied bird feeder. Harry would sometimes sprinkle feed on
the ground to provide the turkeys added sustenance. However,
the turkey troop has grown to over a dozen birds and has become
more of a nuisance. Last week, he found the turkeys pecking on
the glass door, demanding to be fed. However, Harry decided
enough was enough and shooed the birds away.
The turkeys gave up and were leaving the yard when a large gray
fox entered the picture. In such a situation, I would have
expected the fox to end up with a turkey dinner, albeit without
the cranberry sauce and stuffing. Not so. The turkeys grouped
together with the puffed up males in front and, instead of
retreating, marched towards the fox. In the woods behind the fox
were four deer, totally ignoring both fox and turkeys. The sly
fox, after a period of indecision, decided the turkeys had the
upper hand and fled the scene. Harry recalled that some time ago
a mailman in a neighboring town was attacked by wild turkeys
and had to retreat back to his truck to escape bodily harm!
I especially enjoy writing about animals that appear to have a
degree of intelligence that we humans normally reserve for
ourselves. For example, a common view has been that humans are
the only species that uses past experiences to plan ahead or think
about the future. However, I only have to look out in our backyard
and watch the squirrels digging up my lawn retrieving the nuts
and acorns they stored there last fall. They obviously planned
ahead for the winter. But, was this just something programmed
in the squirrels’ genes and triggered by the changing seasons?
In the Newscripts section of the January 22 Chemical and
Engineering News, Faith Hayden goes a step further and asks the
question, “Are red squirrels psychic?” She cites work published
last year in Science about the competition between trees and
squirrels, the trees using a “swamp and starve” tactic to keep
squirrels from eating all its seed. With lots of oak trees in our
neighborhood, it’s clear that some years there are unusually large
numbers of acorns, other years not so many. If we ascribe a
motive to the tree’s variable production of acorns, it could be that
the lean crops of acorns tend to starve the squirrels and reduce
their population. With a smaller population, when the tree
produces a bountiful crop of acorns, there won’t be enough
squirrels to eat all of them and the seeds survive.
The study cited by Hayden says that both American and Eurasian
red squirrels have found the secret as to the tree’s next year’s
productivity of acorns. The squirrels will produce a second litter
of baby squirrels in advance of a bountiful seed production by
the trees. The female squirrel may even conceive a second litter
while still nursing her first litter. This in itself is surprising
because lactation in mammals generally tends to suppress
ovulation. How do the squirrels know what the trees will
produce? That’s a mystery. Do they “count” the number of
flowers or buds or pollen cones? And aren’t we crazy to ascribe
motivation to a tree? Maybe not!
We’ve discussed other examples of looking ahead in animals.
Some time ago, I wrote about the work of Nicola Clayton and her
colleagues on western scrub jays. There’s a profile of Clayton
and her work by Virginia Morell in the February 23 issue of
Science. In 1995, Clayton moved to the University of California
at Davis from the UK. At Oxford, she had shown that Eurasian
jays and tits had excellent memories in the caching of food and
that the hippocampus region of these birds’ brains grew as they
stored seeds in more and more different locations. When she
moved to California, she found western scrub jays in abundance
and began observing their behavior in the wild.
I wrote about her work that revealed the jays would steal from
other jays and that a jay would store some food in one area but
notice that another jay was watching. The first jay would then
return when the other jay was not around and move the food to
another location. This led her and a co-author at the University
of Cambridge to publish a paper in Nature claiming that the
scrub jays have so-called “episodic-like” memories. To store an
episodic memory is to store a memory of a specific episode in
the past, something we humans do all the time – even if we older
folk have trouble dredging up these memories later in life! Her
co-author, Anthony Dickinson, admits that when he first heard of
Clayton’s assertion that the jay had an episodic memory he
thought it was “outrageous”. He became a convert after
collaborating with Clayton on further experiments on the jays.
Dickinson wasn’t the only convert. At UC Davis, Clayton met
Nathan Emery, who was studying primates and would tell
Clayton about the various things that his apes could do that no
other animal could do. Clayton disagreed and said her birds
were just as smart. Emery not only became Clayton’s
collaborator but also ended up being her husband! In 2000, they
moved to England and took some scrub jays with them.
Clayton and her colleagues have published many papers on the
mental skills of food-storing birds, the latest being one in the
February 22 issue of Nature and is co-authored with Dickinson
and two of Clayton’s graduate students. This paper reinforces
strongly the view that the jays have episodic memories and use
the memories to plan for the future. The two grad students,
Caroline Raby and Dean Alexis, put the jays into an interesting
situation. They were placed in a “suite” with two adjoining
rooms, where they stayed overnight in what I’ll call the living
room. The next day they were moved to one of the adjoining
rooms. One room was a jay bed and breakfast, supplied with a
plentiful amount of pine nuts. The other room was devoid of any
food items, not a place a hungry jay would enjoy. It was like the
difference between the Ritz and a sleazy motel.
After spending a few days in the different rooms, the jays were
placed in the suite with free access to either room. The “living
room” contained a plentiful supply of pine nuts. What did the
jays do? Without hesitation, they started taking nuts from the
living room and stashed them away in the “motel” room! They
certainly seemed to remember their times spent in that room and
wanted to be sure that if they found themselves there again they
wouldn’t go hungry. It sounds like episodic memory to me!
Once again, we see that the use of the term “birdbrain” used in a
derogatory sense is quite unwarranted. Now if the trees start
outwitting the squirrels again I’ll really be impressed!
Allen F. Bortrum