Mack makes a cogent point. Naturalists regular remark that
the predators cull the herds (and flocks) of the weak and sickly.

Bill Kaufman
Woodinville, WA





on 1/13/07 6:04 PM, Kevin Mack at kmack at paws.org wrote:

Hi Tweets,

I think Bob makes a good point here. The weights for different species that
are listed in the texts are a good reference, but they don't necessarily
represent the entire range of possible weights for a species. It's
reasonably safe to assume that the birds that become prey are not going to
be the healthiest, fittest, most powerful individuals. They may already
have issues that have led to significant decreases in their body weight. We
routinely receive ill or injured birds at our rehabilitation center that are
less than half of even the low end of recorded weights for their species.
They still appear to be the same size as a healthy bird, but if you look
beneath the feathers you find nothing but skin and bones. An earlier post
mentioned a Merlin carrying a Rock Pigeon. Yes, it is hard to believe that
a 190 g Merlin could carry a 270 g healthy pigeon, but what about a190 g
Merlin carrying a 100g, extremely emaciated pigeon? That definitely seems
possible to me.

----------------------------------------------------------------------------
--------
Kevin Mack
Naturalist, PAWS Wildlife Rehabilitation Center
425-787-2500 ext. 854
P.O. Box 1037 Lynnwood, WA 98046







From: Bob Flores [mailto:rflores at nctv.com]
Sent: Saturday, January 13, 2007 9:38 AM
To: William Kaufman; Bud E-mail; Tweeters
Subject: Re: [Tweeters] Peregrines carrying ducks

I once came upon a peregrine carrying a male mallard because of my action
the peregrine has dropped the bird and I went over to see what it was. The
mallard still not eaten was rather light in weight. This is not unusual in
the winter months but is rarely indicated in text when one reads of a birds
"normal" weight. This occurred in Nevada about 8 years ago at the great
Stillwater Marshes.

Bob Flores
Othello, WA
----- Original Message -----
From: William Kaufman <mailto:beaux at u.washington.edu>
To: Bud E-mail <mailto:bud at frg.org> ; Tweeters
<mailto:tweeters at u.washington.edu>
Sent: Friday, January 12, 2007 4:07 PM
Subject: Re: [Tweeters] Peregrines carrying ducks

on 1/12/07 4:45 PM, Bud E-mail at bud at frg.org wrote:

Hi,
Peregrines do carry ducks regularly but I think that there are several
factors influencing this behavior.
For example, we have the world's largest peregrine residing in Washington,
the Peale's Falcon (incidentally, the type specimen was collected somewhere
in south Puget Sound by Titian Ramsey Peale while he was a member of the
Wilkes Expedition).
Female Peale's Falcons can weigh 1,350 grams (48 ounces) which is 3 pounds.
That's a big peregrine. There are male Gyrfalcons that weigh in at 3 pounds
or less.
Since they are so much bigger, Peale's are able to carry a larger prey item
than the smaller, lighter Tundra Peregrine. Although I have to say that I
once followed a tundra bird as it carried a Blue-winged Teal (very low to
the sand) for over two miles on Padre Island, Texas. But I was also pushing
her.
To complicate matters, male peregrines usually weigh about a third less
than a female. So they are less capable of carrying the large duck species.
They will take a few GW Teal, etc. but usually they seem to prefer smaller
birds, like sandpipers which they can carry off and eat with no problem.
Most of the successful hunts that I have observed, primarily on the Samish
Flats, have involved adult female peregrines and Bufflehead or GW Teal. A
female peregrine can pack these quite nicely. These seem to be a preferred
prey on Samish. The Wigeon kills are a different story. I have usually seen
the falcons eating these heavier


You mention body weight (size) of the preditor but not the comparative
weight of the prey. . .

A reasonable comparison. . .

Bill Kaufman
Woodinville, WA

birds directly on the ground. They might be able to carry them, as Kelly
mentions, but certainly not with a hungry Bald Eagle after them.
A falconer, Brett Gaussoin, reportedly observed an adult female peregrine
carry a recently caught GW Teal up to a good elevation over the
predator-dense Lummi Flats in winter and eat it entirely on the wing. This
behavior was interpreted to be a response to avoid kleptoparasitism by other
raptors on the ground.
I suspect that there are many other factors involved in carrying ducks. For
example the level of hunger, motivation and personality of a specific bird,
whether there is a strong wind, the appearance of competitors, the presence
of strong updrafts at cliff nest sites, stuff like that.
I think that the main point, for me anyway, is that it is always noteworthy
to see a successful peregrine hunt. In my experience, witnessing these
events is relatively rare.

Bud Anderson
Falcon Research Group
Box 248
Bow, WA 98232
(360) 757-1911
bud at frg.org

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