As a coastsider, I can attest to the fact that Myrtle Warblers are more common on the coast than elsewhere that I have seen in the Bay Area. Similarly, I have found that Myrtles are way more likely when you are in good moist riparian habitat. But in other spots that are more open or dry, like my backyard, Audubon's is the expected and Myrtle are quite rare.
From: <southbaybirds...> <southbaybirds...> On Behalf Of Bill Bousman Sent: Sunday, November 11, 2018 9:33 PM To: <southbaybirds...> Subject: Re: [southbaybirds] Palo Alto warblers
Other numbers concerning Yellow-rumped Warblers:
From banding data at the Coyote Creek Riparian Station in the 11 years from 1986 to 1996, the number of Myrtles was 794 and the number of Audubon's were 2847, thus 22% were Myrtles.
From banding data at Wool Ranch from 1970 to 1972 (but only in spring and fall), the number of Myrtles was 22 and the number of Audubon's were 151, thus 12% were Myrtles.
Observers in Central California became interested in the proportion of the two subspecies in the late 1960s and this culminated the following table based on CBC data (count circles not described) for five major regions (Am. Birds 27:660): Region Yellow-rumped Warbler Percent Myrtles Outer Coast 2089 42.0 Inner Coast 440 11.6 Inner Coast Range 625 3.8 Central Valley 2239 0.7 Sierra 11 0.0 [The printed table had 4.2 percent, but was corrected in a subsequent volume.] They also commented that "an apparent difference in habitat preferences exists between Myrtle and Audubon types. 'Myrtle' Warblers basically prefer riparian growth, dense lowland oak woodland or residential parks grown to dense stands of mature deciduous trees. 'Audubon's' Warblers, on the other hand, prefer open or newly developed residential areas with scattered small trees and shrubs."
Our Myrtles are probably all the subspecies hooveri that breeds in Alaska and the Yukon and not coronata that nests in northwestern Canada across to the east coast and winters in the southeastern U.S. The subspecies hooveri was named for Theodore Hoover, the President's older brother, who eventually became Dean of Engineering at Stanford. The older Hoover was an active birder while enrolled at Stanford and became attracted to the valley of Waddell Creek. Later, he purchased much of that land and his granddaughter gave it to the state, now called Rancho del Oso.
Bill Bousman Menlo Park
On 11/10/2018 7:48 PM, Steve Rottenborn wrote:
Earlier this morning (10 Nov), birding at the Palo Alto Regional Water Quality Control Plant produced two Palm Warblers (one near the northeast corner of the plant and one near the southeast corner) and a late Wilson's Warbler about midway along the east side of the plant. Of the 120+ Yellow-rumped Warblers there, all that I saw well were Audubon's except for one Myrtle (I'm reporting this not because Myrtle is rare here, as it isn't, but I don't often see ratios of the two reported in the South Bay). About 250 Bonaparte's Gulls were feeding in the tanks at the plant, visible only when they'd get up and fly around over the plant.
At the southeast corner of the Palo Alto Flood Control Basin, Adobe Creek had a House Wren, an Orange-crowned Warbler, and 3 Myrtle Warblers among 60 or so Audubon's.
This evening, 2 adult Snow Geese and 4 Aleutian Cackling Geese were with 40 Canada Geese in eastern Morgan Hill, in the field north of Diana Avenue and west of Hill Road.
Steve Rottenborn Morgan Hill, CA
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