Friends!

Golden Gate Audubon Society First Friday Birdwalk, October 5, 2018. Tilden Nature Area, parking lot to Jewel Lake and back by way of the boardwalk.

Topic today was again feathers: Ptilochronology (the study of feathers through time), growth bars (the growth cycle of a feather is marked off each 24 hours by a dark [daylight-deposited] and light [night-time deposited] pair of bands), and is evidence of the nutritional status of the bird during the feather's development. The field is only 30 years old (Thomas Grubb's first paper using ptilochronology was published in 1989) but there is enough research that Grubb published Ptilochronology: Feather Time and the Biology of Birds (Oxford University Press), in 2006.

Here are the 34 species seen by 40 observers:

Canada Goose 2
Wild Turkey 3
Anna's Hummingbird 2
Great Egret 1
Turkey Vulture 1 makes it official!
Red-shouldered Hawk 2
Hairy Woodpecker 1
Northern Flicker 1
Pacific-slope Flycatcher 1
Black Phoebe 2
Hutton's Vireo 3
Warbling Vireo 4
Steller's Jay 1
California Scrub-Jay 1
Common Raven 2
Chestnut-backed Chickadee 2
Oak Titmouse 2
Red-breasted Nuthatch 3
Brown Creeper 4 Bird O'the Day: lots of singing!
Bewick's Wren 1
Wrentit 1
Varied Thrush 1
Hermit Thrush 1
American Robin 3
Lesser Goldfinch 5 feeding on thistles on the Jewel Lake sandbar
Fox Sparrow 1
Dark-eyed Junco 5
Song Sparrow 2
California Towhee 3
Spotted Towhee 1
Yellow-rumped Warbler 3
Black-throated Gray Warbler 1
Townsend's Warbler 1
Western Tanager 1

November’s theme is, of course, Wild Turkeys!

Best of Boids!
Alan Kaplan