9.16 Cassin's
Sparrow
This morning, Luke Cole, Dan Singer, Adam Winer, David Armstrong,
Lang Stevenson and others headed over to Stinson Beach. After
parking near the Parkside Café, we headed over to the
dry grass along the east shore of the creek. After about 15 minutes
of looking, Dan Singer refound the bird. The following description
was written from memory later that morning.
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Description:
A small brown bird quite similar in appearance to a sparrow. The lower mandible appeared to be pale, perhaps due in part to the low angle sun. The maxilla appeared to be contrasting horn color. The overall plumage was fairly warm. The crown feathers were streaked light rusty brown with paler bases. The face was fairly blank with a prominent eye ring that was at least one shade paler than the rest of the face. The eye was dark. There was a post-ocular strip of roughly the same color as the streaking on the tips of the crown feathers. The throat was fairly pale, contrasting noticeably with the rest of the face. The nape was not observed.The plumage on the upper parts was somewhat cryptic. In general, the fringes were buffy and there were dark subterminal spots on the wing coverts, but the spots varied coloration from nearly black on the greater coverts to being concolorous with the streaking on the crown on the lesser coverts. The remiges were noticeable paler than the coverts with edges that were quite pale. The wing structure was remarkable; the primaries were only slightly longer than the tertials, suggesting a short-distance migrant or sedentary bird. Tail length was hard to assess. The central rectrices showed noticeable barring on them. Leg color was not observed.
The bird was confiding, sometimes approachable to within 15 feet or less, but rararely left the cover of the tall grass for more than a few seconds, dramatically complicating observation.
Analysis:
Once we realize that the bird is a sparrow, the identification becomes relatively straight-forward. It's widely believed that the barring on the central rectrices is in fact diagnostic for Cassin's Sparrow, but do note the photograph of a juvenile Rufous-crowned
Sparrow below:The quality is only fair, but barring on the central rectrices is just visible. However, there are several other field marks that are used. The streaking on the crown, dark subterminal spots (just visible in the photo just above the analysis section), contrasting dark tertials put the bird firmly in the Cassin's/Botteri's complex while the barring on the tail leaves only Cassin's Sparrow. The extensive streaking on the breast and flanks makes this a juvenile CASSIN'S SPARROW. Better photos of this bird may be found at http://fog.ccsf.cc.ca.us/~jmorlan/casp091704.htm.
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9.18 Western SF
PACIFIC-SLOPE FLYCATCHER 2 at East Wash (Sep 18)
YELLOW WARBLER 35 at Middle Lake (Sep 18)
TOWNSEND'S WARBLER 2 at Middle Lake (Sep 18)
WESTERN TANAGER 2 at North Lake (Sep 18)
AMERICAN GOLDFINCH 25 at North Lake (Sep 18)
Pacific-slope Flycatcher (1)
"Western" Flycatcher (1)
Hutton's Vireo (1)
Warbling Vireo (1)
Steller's Jay (3)
Orange-crowned Warbler (1)
Yellow Warbler (1, 3)
Townsend's Warbler (1, 3)
Western Tanager (2, 3)
Fox Sparrow (1)
Black-headed Grosbeak (1)
American Goldfinch (2)
Locations:
1) East Wash (Sep 18)
2) North Lake (Sep 18)
3) Middle Lake (Sep 18)
9.21 Dickcissel
I received a call from Hugh Cotter
indicating that a DICKCISSEL had been found at Fort Mason. I
hurried over and found Hugh, Alan Hopkins, Calvin Lou and Kevin
McKereghan all present. After patiently waiting for about 15
minutes, the bird was refound and I managed the following photographs
over the next hour or so.
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You can contact me via email.