White-rumped Sandpiper
Coyote Creek Riparian Station
Alviso, Santa Clara County, California
Fri 09-05-1997
I noticed Luke Cole was situated on a levee between the sewer ponds to the south and the bird and he appeared to be taking notes although he did not have a spotting scope. Luke eventually came by and advised that much better views could be had from that levee which could be reached fairly easily from the far side of the pond the White-rumped was in. Several of us went there where we were joined by Jack Cole and Ed Frost. There we had excellent close views of the White-rumped Sandpiper in perfect light through scopes. The bird could be seen easily and was easy to refind each time the flocks flew when disturbed by a passing Northern Harrier.
The following description is based on notes written while watching the bird, discussion with other birders at the time and on memory:
A large "peep" mostly grayish or grayish-brown in color, decidedly larger than nearby Western and Least sandpipers, approaching the size of nearby Pectoral Sandpipers although direct comparison was not available. The most striking features were the combination of very long primaries extending beyond the tail, and a solid-gray breast-band strongly demarcated from the white underparts. Closer inspection revealed the following:
The bill was dark with a hint of olive-green at the very base visible only in very strong light. The culmen was straight but the lower mandible curved downward slightly.
The head was essentially gray with an obvious pale-gray supercilium and a faint pale-gray crescent under the dark eye.
The gray breast had fine streaks throughout, these streaks extended along the sides and flanks, marking the otherwise white underparts.
The back was a somewhat paler gray than the rest of the upperparts. The scapulars and wing-coverts were gray-brown (browner on the greater coverts) with a mixture of wedge-shaped black feathers edged in gray. The tertials were gray with very narrow pale rusty-brown fringes.
The primaries were also gray-brown in color, not black as on most shorebirds. The primaries showed a substantial projection beyond the tertials extending beyond the tail.
When the bird preened, it was possible to get good views of the rump and uppertail coverts. I judged the rump proper to be gray, but the uppertail coverts were conspicuously white forming a square patch when seen in flight. This patch was barred extensively with black laterally and distally. In flight, the darker rump projected slightly into the top of the white uppertail coverts coming to a shallow point. I looked for dark extending down the middle of the rump, but could not detect any.
The rectrices were gray with very narrow white fringes at the tips and brownish lateral edges. They were blunt-tipped, not pointed.
Legs were black and it was possible to see that there was no webbing between the toes. Rear toe present and slightly elevated.
In flight, the bird showed no obvious wing stripe, but the underwings were clearly whitish when the bird raised its wings on one occasion.
The bird was still there when we left. We met Clyde Morris, Joelle Buffa and Mike Feigner who were heading out to see it. Later Mike told me that a Prairie Falcon flushed all the birds before he got a chance to see it this time. Later I met Allan Walther and John Mariani who were going out to look for it. Allan intended to attempt photographs.
Other interesting birds seen at the waterbird ponds today include a White-faced Ibis, a Stilt Sandpiper, about 10 Pectoral Sandpipers and at least 20 Lesser Yellowlegs.
DISCUSSION
Based on the extensively gray breast, I judge this bird to be an adult in basic (winter) plumage or possibly molting into basic plumage.
I have seen this species only once before in California, at the Carmel River in June of 1978. This is an extremely rare bird in California with 12 previously accepted records.
--
Joseph Morlan
380 Talbot Avenue #206
Pacifica, CA 94044