Biology Reference
In-Depth Information
is to dig a little hollow, put a piece of meat in it, and then cover it with leaves or grass. In snow, the
raven simply buries the choice morsel and lets the snow fall back to cover it. Heinrich's studies have
revealed two particularly fascinating aspects to this caching behavior.
First, ravens have excellent short-term memory both for the precise location of their own caches
and for the places where they've observed other ravens caching food; however, their memory for
caches is poor after two weeks and almost nonexistent after a month. Second, ravens will make false
caches—that is, apparently create a cache, but deposit no food in it. This behavior seems designed to
reduce pilferage of caches, especially by subordinate ravens, which frequently attempt to steal the food
cached by more dominant ones.
Ravens are far less gregarious than crows. Often solitary, they also commonly travel in pairs or very
small groups, and are rarely found in large assemblages except in special circumstances, as when num-
bers of them gather around a carcass. That's not to say that ravens are antisocial birds, though. Indeed,
Heinrich has documented behavior indicating that ravens may have rich social interactions among sib-
lings or members of small groups, and I personally observed a group of them interacting in the follow-
ing incident.
One day in early summer I heard what were distinctly raven calls emanating from the lower part of
one of our pastures. I thought little of it at first, but my curiosity grew as the uproar became more and
more prolonged. Even more curious was the fact that the ravens seemed to be stationary. Finally, after
additional time had elapsed, I walked down to the pasture to investigate.
There, close to the woods, I found five ravens relentlessly harassing a thoroughly bewildered young
red fox. No matter which way it turned, the ravens flew at it to drive it in another direction, herding
it back and forth with great effectiveness. I watched for a few moments, then moved a bit closer, at
which point the ravens suddenly broke off their chase and flew away. The young fox, as yet unharmed,
promptly scampered into the woods.
Just what did this mobbing behavior signify? It seemed clear to me that the ravens were cooperating
in this venture, whatever its purpose. Did they intend to kill the fox, or were they merely enjoying a bit
of bullying? From their extremely aggressive behavior, I speculate that, given a little more uninterrup-
ted time, they would have completely exhausted the fox and ultimately killed it.
There are other unanswered questions, as well. Were the five ravens a family, or were they merely a
group that had assembled temporarily to attack the fox? If not family members, were they ravens that
recognized one another and associated or cooperated with each other from time to time? Clearly there
is still much to be learned about the behavior of these complex birds.
One other particular facet of raven and crow behavior that I've been able to observe extensively is
their inordinate fascination with golf balls. We hit golf balls off our patio into the field below the house,
and that has generated a number of incidents involving both crows and ravens. Likewise, we've exper-
ienced some unusual encounters between crows and golf balls on the golf course.
