>From Terres (1980) The Audubon Society Encyclopedia of North American Birds:

"The male marsh hawk in his spring courtship flight may fly with shrill
cries in a series of graceful undulations, like giant U's, over the
home-nesting marsh in which the female may be incubating her eggs."

I was witness to this display flight this past Memorial Day weekend at
Page Springs, on the south end of Malheur NWR, Harney Co., Oregon. The
male Northern Harrier (new name from 1980) flew very slowly, with deep,
deliberate wingbeats, down the canyon following the river out into the
marsh.

Up, up, up it flew, then (WHAT'S THIS?) right on over upside down in a
slow loop! Three flaps while in the upside-down loop! Then back down and
up again; another loop! And the shrill cries turns to deeper chuckles
as the bird completes the loop. Up, up again, oh... it didn't make it -
instead a quick turn to make the described U-shaped arc. Over 5 days I
saw this loop-to-loop flight about 3 or 4 times.

I saw an article and pictures of inverted flight by White-winged Scoters.
But those birds flipped over horizontally, and just momentarily. I've never
heard of a bird doing a verticle loop! And he made it seem so effortless.

I've decided: when I grow up (don't my kids wish!) I'm going to be
a male Northern Harrier, and spend the lazy days of summer flying loop-
to-loops in the sky!

--
Greg Gillson <gregg at tdd.hbo.nec.com>
Hillsboro, Oregon