falcon had gone I saw it stooping hard

on what I assumed was the eagle. How-

ever, in the scope, I saw it stoop 6-10

times on the Snowy Owl, which flipped

up to meet it eve1y time. The Gyrfalcon

then left, flying towards downtown Duluth.

(Clum and Cade (1994) reported one pre-

vious record of a Bald Eagle robbing

prey from a Gyrfalcon).

On 27 December 1993 I obse1ved a Gyr-

falcon land on the Cargill B grain elevator.

At 2:55 P.M. I placed a pigeon in front of the

Gyrfalcon and circled around the elevator

to observe from a distance. As I ap-

proached, at 2:57, the Gyrfalcon was stoop-

ing at something at the base of a pile of

railroad ties. This turned out to be a Snowy

Owl (L28, adult female) that I had observed

at 2:34 sitting on a dirt pile at Bayfront

Park, about 3/ 4 mile distant. The owl cow-

ered at the base of the ties and did not

jump up Cit clutching a pigeon).

On 22 ]anua1y 1994 I observed a

Snowy Owl (L25, adult female) sitting on

a tall powerline pole at the end of Winter

Street in Superior. No interaction was ob-

seJved with the Gyrfalcon sitting on the

next pole west. The owl did not react

when the Gyrfalcon left.

On 20 April 1994 a switchman for the

Soo Line railroad on the Port Terminal

called and reported a Snowy Owl (L26,

immature female) being stooped on by a

Peregrine and then getting harassed by

gulls at about 11:00 A.M. I could not find

the owl at 12:00 P.M . and it was not seen

again that season.

In December 1999, I had three reports

of a Peregrine stooping on Snowy Owls.

One, by Anthony Henzel, is described

below:

"On 2 December 1999 I was driving

through the Port Terminal in Duluth

when I noticed a falcon diving steeply

from an initial altitude of about 30 feet.

Through my binoculars I could see that it

was a Peregrine. "

"As I watched it plunge toward the

ground I discovered the object of the

bird's intentions. An immature Snowy

Owl was standing directly beneath the

Peregrine, hunched next to one of the

large moorings which are common at the

port terminal."

"The owl was standing in a defensive

posture with its wings raised over its

head and fanned out horizontally. It

stood there with its bill open, neck arch-

ing forward, bead looking up, and eyes

glaring at the approaching Peregrine. Just

before the falcon reached the Snowy, the

young owl ducked and the Peregrine,

having made no contact, turned quickly

and made a nearly vertical climb back up

to a height of about 30 feet. Again it

turned and dove at the owl below. This

time, as the falcon approached the

Snowy, the owl jumped into the air,

flipped upwards, and grabbed at the

passing Peregrine with its talons, missing

it by a wide margin. This was the only

time it took any kind of an aggressive

action toward the Peregrine. "

"Yet again the falcon climbed, turned,

and dove at the owl which this time re-

treated closer to the mooring, cowering

close to it as if unable to decide what to

do. The Peregrine swung past the owl,

made a half-hearted grab at it, then as

before, quickly ascended and turned to

begin the next attack. "

"This interaction was repeated perhaps

six or seven times before the Peregrine

suddenly broke off the attack, banked, and

flew out of sight to the southwest. The

entire episode lasted perhaps 60 seconds.

The falcon never appeared to actually

strike the owl, and after the encounter, the

Snowy remained crouched beneath the

mooring, wings raised and wide eyes star-

ing, and it was still there when I left. "

Peregrines and Gyrfalcons represent a

considerable threat to wintering Snowy

Owls. Given that Gyrfalcons are consider-

ably larger (about 50% greater mass for

females) , they would appear to be the

greater threat and this is also suggested

by the stronger defensive response (i.e.

jumping up with feet extended) to Gyr-

falcon attacks.

Snowy Owls also change their roosting

behavior when large falcons are present,

typically choosing sites affording greater

protection, e.g. hiding in jumbled chunks

38 The Loon Volume 72