[Tweeters] Peregrine prey

JChristian Kessler 1northraven at gmail.com
Sat Mar 7 21:51:40 PST 2009


there is something fascinating in these data, taking those species which
reach double digits, we have:

sora 75 grams
woodcock 200 grams
rock pigeon 270 grams
mourning dove 120 grams
yellow-billed cuckoo 65 grams
northern flicker 130 grams

the sora & yellow-billed cuckoo are significantly smaller than the other
predominant prey species. having no idea of the habitat (tho clearly marshy
areas close by, but presumably also shrub edge), I won't speculate on
relative population densities, but it was interesting to note that the prey
identified included only one starling (82 grams), which one would expect
would be relatively common in the habitat, and 1/3 larger than the cuckoo.
I did not look up weights for the many other species that were only 1s & 2s,
but the robin (77 grams, same weight as the cuckoo) would, I expect, be more
common than the cuckoo.

certainly not the prey distribution this amateur would have expected. [all
weights from Sibley, convenient beside my laptop]

Chris Kessler
Seattle


On Sat, Mar 7, 2009 at 12:15 PM, Dennis Paulson
<dennispaulson at comcast.net>wrote:


> John Sproul called my attention to a website that discusses Peregrine

> Falcons that tried to nest unsuccessfully in a tower across from the

> University of Michigan's Museum of Zoology (

> http://www.ummz.lsa.umich.edu/birds/peregrine/um-peregrines.html). People

> working in the bird collection have been keeping track of the prey dropped

> from the tower, where the Peregrines have been roosting for several years. I

> have summarized what they found in 2007, between March 11 and October 18. I

> didn't include unidentified prey remains, including a few unidentified rails

> and cuckoos and thrushes. The site is near a marsh and a river, thus the

> water birds. Obviously some birds are much more vulnerable than others to

> the Peregrine mode of hunting.

> Birds such as pigeons and doves, flickers, and cuckoos that commute by

> flying above their breeding habitat seem especially prone to be prey. Note

> that a fair number of prey items are what we would consider in the size

> range of Merlin food. Note also that among the most frequently documented

> prey are birds that we don't see all that often. Bird-eaters are better

> birders.

>

> Pied-billed Grebe 6

> Horned Grebe 5

> Least Bittern 2

> Green Heron 1

> Bufflehead 1

> Virginia Rail 3

> Sora 15

> American Coot 1

> Killdeer 3

> Dunlin 1

> Wilson's Snipe 3

> American Woodcock 18

> Bonaparte's Gull 1

> Rock Pigeon 15

> Mourning Dove 17

> Yellow-billed Cuckoo 22

> Black-billed Cuckoo 3

> Belted Kingfisher 2

> Northern Flicker 12

> Great Crested Flycatcher 1

> American Robin 2

> Gray Catbird 2

> Northern Mockingbird 1

> Brown Thrasher 3

> European Starling 1

> Scarlet Tanager 1

> Rose-breasted Grosbeak 5

> Eastern Meadowlark 3

> -----

> Dennis Paulson

> 1724 NE 98 St.

> Seattle, WA 98115

> 206-528-1382

> dennispaulson at comcast.net

>

>

>

>

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