Hi Tweets,

Well, an unequivocal sign of spring: two crows following me for half a
block giving me *major* lip for walking too close to the tree by my house
in which they're thinking of nesting again this year. Their work's cut out
for them: this is the same big, skinny fir that one of the neighborhood
Bald Eagles (wow! how *many* cities in the world can ya just offhandedly
say something like 'the neighborhood Bald Eagles' ?) likes to park it in.

When I come home from work in the evening, I see large flocks of crows
heading for evening roost. So a few days ago I started wondering whether
the crows which are yapping at me and running other crows offn' the
property are the same ones happily flocking and roosting together. That
started me wondering just how they do both, and how they mediate the
switchovers.

They and the rest of the neighborhood crows seem to be at the point where
two distinct but mutually contradictory behavioral motives (can I say
'motives' without getting thumped for anthropowhatever? I mean, corvids are
*smart* and all a motive is, is intent) seem to be at work.

Daytime, they're refurbishing nests, mutually preening, all that
pair-bonding, lovey-dovey mushy stuff we used to fold flat our popcorn
boxes and skim 'em at the screen at when it came on during the cowboy
movie. They're also hostile to other crows.

Well, they're not ready to stay at the nest overnight yet, so they're still
gathering, flocking, moving 'en masse' to various pre-roost staging sites
then to the roost site itself, and roosting communally, which means they
have to inhibit that hostility, and co-exist in large numbers at close
quarters from initial gathering. Then the same in reverse in the morning.

This means in the morning at this time of the year they're ratcheting up
their intolerance of other crows incrementally as a.) it get light, and b.)
the daylight duration lengthens, and then gearing it down in the evening.
Is this intolerance/tolerance cycle light-related? Or a side-effect of
territoriality? Or a spin-off from the progressive intensity of their
pair-bond until their young fledge?

Forgive me if I'm not asking this well, or making much of what's painfully
obvious to most, but I'm curious about how they amplify, then inhibit two
diametrically-opposed behavior sets in the same 24-hr period (you might
say, if you can't resist an atrocious pun, their behavior is like night and
day. Fortunately, I can; just not inclined to ;-)

So, I wonder if those late afternoon/early evening get-togethers don't
serve the purpose of allowing them to make the changeover, giving them the
chance to get all the abuse off their chests and gradually settle back into
communal harmony (well, sort of harmony. Crow style harmony), until the
next day, and finally that day they stay at the nest.

At one location fairly nearby, I watch crows gather, a small bunch at
first, then as pairs, singletons, and small groups of five or six fly in,
the noise level escalates. Each arrival is met with a chorus from the group
and the arrivals argue back. Flocks of twenty to thirty arrive high and
drop, mock-stooping and jinking and rollercoasting. When the flock size is
in the hundreds (*party*, dude!), waves and choruses of loud caws erupt
every time the flock begins to move about as a flock. When the sun's about
fifteen-twenty minutes gone, they head up and out, letting everyone who's
interested know about what they're doing, flying north over the open
saltwater water of Burrard Inlet to the forests of the North Shore
mountains about five miles away.

Interestingly, once gone, they're silent on the trip. Even a couple miles
out in the middle of the Inlet, with the flock going over looking like a
Thousand Plane Raid, there's not a sound. The same birds which a few hours
before would have been at war.


Michael Price The only alien planet is Earth.
Vancouver BC Canada
mprice at mindlink.net - J. G. Ballard