[EBB Sightings] Swainson's Hawks in another nearby field

It's great to see these beautiful raptors almost in
our back yards. Thanks for keeping the information
flowing David.

> Wiser birders, pray tell: how can you best tell they
> are Swainson's Hawks, 
> and is this normal behavior for them, to hang out in
> big groups at buffets?

With extraordinary deference and respect I pass on the
following (which I think might answer most of your
questions) from Allen Fish, Director of the Golden
Gate Raptor Observatory:
"East Bay Birders' Listserv has had great accounts of
a mouse exlosion, and many aerial prdators in
attendance this past month near Clifton court Forebay,
east of the Altamont Pass, along the Byron Highway. 
Most interesting has been up to 80 Swainson's Hawks.
Reports go back to June 20th and last through July
5th. Although I haven't seen this gathering, many of
the Swainson's seen there .... sounded like yearlings,
aka SY's, or subadults.

These are Swainson's hatched in 2004 that have made
one trip to Argentina (0r maybe just Mexico?) and
returned this past spring. Because of the arduous
migrations, they haven't become strong enough to
breed, so they simply "hang out" in loose flocks all
summer in California and find prey outbreaks,
particularly mice and grasshoppers.  They follow
tractors, diskers, and agricultural burns.  This
particular flock is unusally western, even dipping
into Alameda county; I have heard reports of flocks
mainly from around Stockton in the the past.

The Byron flock may very well be active for a few more
weeks, and could be worth a detour.  If you go, here's
how to ID a subadult: (1) they are ragged and molty
looking especially in the head, body, and wings. 
Sometimes the head appears whitish from the feather
loss.  (2)they have a juvenile chest pattern, that is,
an incomplete bib, COMBINED with (3) an adult tail,
which is usually grown in fully, and shows a dark
subterminal band that is at least twice as dark as the
next dark band."  

Swainson's are cool hawks.
Get out and bird.
Bob Power
Oakland, CA

"No birds sang the whole time we were up there. I didn't see a thing.  I still dream about that trip though." Ted Parker, Northern Peru. 1978
From: A Parrot Without A Name. Don Stap. Knopf, 1990

Bob Power
Oakland, CA
Alameda County