At 04:13 PM 10/13/97 -0700, you wrote:

>There may also be some kind of age- and/or sex-sorting here as well.

That's the first thing that comes to mind, for me. The oft-cited (over
the past couple of days, at least) "Handbook" has one possibly relevant
sentence:

"Roughlegs travel more or less spaced out."

I know that when I travel spaced out, I can end up *anywhere*! :)

More relevant, it does mention a few are early migrants in fall and
spring (which in my experience is true of all raptor species, at least
those migrating over our [HawkWatch] two Great Basin sites), and that
kids tend to migrate further south in fall, which could lead one to
think that perhaps kids leave earlier. Hatching year raptors do tend
to leave before the adults, with adult males leaving last, at least with
accipiters (which I know the most about since our projects focus on them).
The adults are reluctant to leave the nesting territory, while the kids
of course have no reason to stay once mommy and daddy stop feeding them
and start acting like gradute students of the Roseanne Barr school of
parenting.

However, the "Handbook" also mentions that some apparently leave their
breeding grounds early, arriving as early as the end of August (!) at
their wintering ground, especially in poor lemming year (leading to more
nesting failures). Again, this is consistent with what I know about
accipiters - we always see a small but steady stream of adult accipiters,
particularly adult female Cooper's hawks, when we start our migration
projects in mid-August. This is at a time when the immy accipiter
migration is at a trickle. By about the first week in September,
immy accipiter numbers begin to rise sharply on the toe of the normal
curve that characterizes their migration. Adults remain at a steady-state
trickle until (usually) the third week of September. Some of these early
female Coops are well-on in their molt, which since they normally don't
molt until after laying indicates to me, at least, that they probably didn't.

Since Rough-legs are our only buteo that can be sexed in flight (in adult
plumages, then not entirely reliably), and since juvies can be identified
easily (at least in light phase birds), you could learn a heck of a lot
more about these early birds you're seeing by observation. Don't need them
in the hand. As adults, they're easier to sex in flight than accipiters
(where size and robustness clues are all you have to go on) so, hey, check
'em out early next fall!



- Don Baccus, Portland OR <donb at rational.com>
Nature photos, on-line guides, and other goodies at
http://donb.photo.net