Rob, I have noticed this too and I wrote on my calendar last Friday
that it was the first time I saw "just the pair" at my house without the
"tribe." I work at home where I look out onto my yard, feeders, and tall
conifers across the street and the crow tribe sometimes converges on my
feeders or gets a handful of hazelnuts from me, so I usually see them
once a day. In the past few days I have seen just a pair here sitting on
the peak of my roof or an adjacent tree. It doesn't seem like they have
completely isolated themselves yet, because when I gave them some nuts
the other day, one of them announced it to the neighborhood and some of
the tribe showed up. That behavior seems to end when they are nesting
(=when I assume they are nesting) when I then usually see just one at a
time here. I am not familiar with all the crow behavior literature, but
I have been under the assumption that crows maintain the same pair bonds
year after year while both are still alive, and that the neighborhood
"tribe" is made up of individuals that are genetically related to each
other more than they are to other "extended family" tribes that share a
common night roost. Anyone who knows more or differently please
enlighten me. I really enjoy it when the pair is nesting, because
whoever is not on nest duty seems to show up daily to get a few nuts and
is a lot tamer than when the group is all together. And when the young
fledge, it's a lot of fun to watch them play and learn what is edible
and how to drink from the stock tank without falling into the water. One
evening in late summer the year before last, I heard a lot of cawing and
went out to see a group of adult and YOY crows (distinguishable by their
new plumage) congregated at the tops of the conifers across the street.
A pair of young crows would take flight, do some sort of aerial dogfight
type of play, and then circle back and return to the group, at which
point another pair would do the same thing. I saw at least several more
pairs do this and couldn't escape the impression that the young birds
were taking turns doing some sort of advanced flight practice. There was
quite a bit of commentary going on in the peanut gallery.

I wanted to chime in about the anting behavior too, because there is an
ant mound across the street from my yard at the edge of the forest and
right near the road. Two years in a row I have observed crows anting
there. What I have seen is birds with one or a few ants in their bill (I
can't tell) perch on a fencepost next to the mound and "preen" the ants
through their feathers. It didn't appear to me that any "eating of ants"
was involved. I will have to find my notes for Gary and Kelly, and I
will keep my eyes peeled for any anting behavior. If I am super lucky,
maybe I can get it on video.

(Crows are also great for letting you know when the pesky neighbor cat
is skulking in your yard.)

Angela Percival
Cooper Point, Olympia
Angela at stillwatersci dot com

------------------------------

Message: 14
Date: Fri, 26 Feb 2010 11:22:24 -0800
From: "Rob Sandelin" <floriferous at msn.com>
Subject: [Tweeters] WHen do crow groups disperse? Or do they?
To: "'tweeters'" <tweeters at u.washington.edu>
Message-ID: <BLU0-SMTP57F1AB5423A7B4A18059C8A33F0 at phx.gbl>
Content-Type: text/plain; charset="us-ascii"

It has been my loose observation that sometime during the spring these
large
groups of crows stop congregating and I assume this is due to
reproductive
pair bonding. But I would be interested in hearing from those who have
the
regular ability to see these groups as to when they stop seeing them.

Rob Sandelin
Naturalist, Writer, Teacher
Snohomish County