Recent postings prompted me to add a few words about cacheing (or hoarding)
behavior, known in a number of bird groups but especially characteristic of
temperate-zone corvids. This behavior is doubtless the key to the survival
of these birds, which are resident at high latitudes. Ever wonder how gray
jays and nutcrackers survive way up in the mountains in the dead of winter?
They spend all fall and even, I think, part of the summer, cacheing seeds
(which, under conditions of cold and/or dryness, remain entirely dormant
and can last that way indefinitely; that's what being a seed is all about).
They have very good spatial memories, and I've always suspected that
selection for the ability to remember where you put something (lacking in
some humans, I think) may have been instrumental in producing the
relatively great intelligence (learning ability) of this group of birds.

Corvids and cacheing go back a long way. There is anatomical modification:
gray jays have salivary glands the saliva from which they use to plaster
seeds (I once watched one do it with a grape) onto branches. There is
coevolution: Clark's nutcrackers disperse the seeds of whitebark and other
pines, which seem to be adapted for the interaction; the buried seeds that
aren't recovered (if for no other reason than that the nutcracker died)
eventually sprout. I read, by the way, that nutcrackers hide an average of
two seeds each in 1400-2000 caches to make it through the winter. There are
population consequences: when there is a really big crop of pinyon pine
seeds in the SW, the high plateaus are crawling with corvids--pinyon jays,
nutcrackers, Steller's and scrub jays--that home in on this superabundant
resource and, presumably, stash them away by the hundreds for the winter.

Other groups that do this include chickadees and nuthatches--again,
probably of importance in their winter survival at high latitudes--and
acorn woodpeckers, which cache large quantities of acorns in single trees.
This is called cluster hoarding, as opposed to the scatter hoarding of
corvids and squirrels. Squirrels appear to find their caches by smell
rather than memory, and they lose track of a lot of them--that's how oak
seeds (acorns) are dispersed. And of course there are even examples of
birds cacheing animal food--the mice, lizards and birds that shrikes hang
up in bushes and on barbed-wire fences, to come back and eat later.

Back to acorn woodpeckers; this species colonized WA rather spectacularly a
few years ago, in Klickitat County when there was a particularly large
acorn crop. In that same year there were masses of Lewis's woodpeckers and
Steller's and scrub jays in the same area, I presumed because of the acorn
crop. Now all of them have declined in the area, the acorn woodpeckers
perhaps back whence they came. I guess this is just another example to me
of the value of knowing about birds--the more you know about their biology,
the more you can understand what you see when you go birding. Watch a crow
foraging next time you can.

Dennis Paulson