Re: Havey Canyon in Wildcat Canyon Regional
Park
Tue, 13 Oct 1998 10:58:25 -0800
From: Kirk Swenson
At 8:30 AM -0700 10/11/98, Peter Rauch wrote:
At one point, the half dozen or so individuals perched in the elderberry flew away - looking up, a sharp-shinned hawk had come to circle over the tree a couple times (it had a slightly notched, squared tail (in Peterson Western Birds, it describes the notched tail as on the male, whereas in [National Geographic Society]'s Birds of [North America] it acknowledges the notch but doesn't say it's just in the male; what's the story here?).
The Golden Gate Raptor Observatory measures tail feather lengths as part of its banding program. The notch is formed when the central retrices are shorter than their neighbors. The GGRO data suggest that male Sharpies are more likely to show the notch than female Sharpies, but there's substantial variation in both sexes, so it cannot be considered definitive. Furthermore, the perception of the notch is greatly influenced by the way the bird is holding its tail. On a completely folded tail a Cooper's Hawk can appear to have more of a notch than a Sharp-shinned Hawk where the retrices meet because individual Cooper's Hawk retrices are more rounded than Sharp-shinned retrices. That said, GGRO data also indicate that male Sharpies are more distinct from female Sharpies in measurable characteristics like size and weight than are the Cooper's Hawk sexes. A bird that looks very Sharpie (very short notched tail, quick twinkly wingbeats, greatly buffeted by the wind, etc.) is likely to be identifiable as a male by an experienced observer.
Kirk Swenson
(former GGRO volunteer taking a break this fall)
Original Message Next Reply Subject List
Re: Havey Canyon in Wildcat Canyon Regional
Park
Tue, 13 Oct 1998 12:01:29 -0700 (PDT)
From: Peter Rauch
On Tue, 13 Oct 1998, Kirk Swenson wrote:
... The GGRO data suggest that male Sharpies are more likely to show the notch than female Sharpies, but there's substantial variation in both sexes, so it cannot be considered definitive. Furthermore, the perception of the notch is greatly influenced by the way the bird is holding its tail. On a completely folded tail a Cooper's Hawk can appear to have more of a notch than a Sharp-shinned Hawk where the retrices meet because individual Cooper's Hawk retrices are more rounded than Sharp-shinned retrices.
The notch was small but distinct, and it was discerned even on a slightly spread tail. When the tail spread wide, it was quite squared off, not at all rounded or arced. That's about all I can recollect/offer on that particular observation.
Thanks for the additional hints on distinguishing the two species and sexes.
Peter
Point Pinole
Tue, 13 Oct 1998 13:50:10 PDT
From: Steve Glover
East Bay Birders,
This morning I went out to Pt. Pinole Regional Shoreline hoping to refind the Clay-colored Sparrow reported over the weekend in the parking lot. I did not refind the bird which was, by the way, only the 5th or 6th [county record]. I did manage 61 species in a loop around the park. There were not many migrants but the weather was so beautiful it didn't seem so bad.
These highlights are in the order I found them rather than in taxonomic order. Hermit Thrush 8+, Am[erican] Wigeon 225+ (they were too backlit to pick out a Eurasian), Varied Thrush 2 (I think these are my first for west county), Golden-crowned Kinglet 1+, Orange-crowned Warbler 1, Red-shouldered Hawk 2, Pine Siskin 6+ (my first this year in the county, #250 I think for the year, and I don't think I saw any last year when they were extremely scarce everywhere), Black Turnstone 27, Raven 4, Merlin 1 (One of the few I've seen in west county but probably regular here in winter), Spotted Sandpiper 9.
Good birding,
Steve Glover
Re: Point Pinole
Tue, 13 Oct 1998 14:33:07 -0800
From: Kirk Swenson
At 4:50 PM -0400 10/13/98, Steve Glover wrote:
This morning I went out to Pt. Pinole Regional Shoreline hoping to refind the Clay-colored Sparrow reported over the weekend in the parking lot. I did not refind the bird which was, by the way, only the 5th or 6th co. rec.
I made a quick stop out there yesterday before heading to work. I also failed to find the Clay-colored Sparrow. Best bird in the hour or so I spent there was a Loggerhead Shrike.
Kirk Swenson
Lake Merritt
Tue, 13 Oct 1998 21:26:51 -0700
From: Larry Tunstall
This afternoon (Oct 13) at Lake Merritt, I saw around 80 Ruddy Ducks, 1 male Lesser Scaup, and 1 female Ring-necked Duck near the islands. There were also Ring-billed Gulls, Western Gulls, Forster's Terns, Brown Pelicans, Double-crested Cormorants, Great Egrets, Snowy Egrets, American Coots, Pied-billed Grebes, Canada Geese, Mallards, Rock Doves, Black-crowned Night-Herons, and the usual motley collection of domestic geese, ducks, and hybrids that has included for some months now an Egyptian Goose (origin unknown).
At the outlet channel through Laney College, there were about 8 American Wigeons (should grow to a much larger group soon), American Coots, Double-crested Cormorants, Ring-billed and Western Gulls, Pied-billed Grebes, Canada Geese, Mallards, Black-crowned Night-Heron, and Snowy Egret.
Larry Tunstall
El Cerrito CA
http://www.best.com/~folkbird/