GGAS First Friday Bird Walk, September 7, 2018

Alan Kaplan


Golden Gate Audubon Society First Friday Birdwalk, September 7, 2018, Tilden Nature Area, Berkeley, CA from the parking lot to Jewel Lake and back.

Today's theme was Molting (not plumages but physiology and ecology of molting). Textbooks and review articles and research results disagree about the roles of photoperiod, sex hormones, thyroxine-T4, prolactin and other influences on molting. Many sources say, "We don't know a lot about the physiology of molt”.

There are many strategies and adaptations for molting in birds. The most interesting things I learned are: Ducks (Mallards and Blue-winged Teals were studied) increase their leg muscles to make for faster water-surface or underwater escape from predators during flight-less periods due to wing-feather molts; Hummingbirds (Ruby-throated was studied) can fly with only three primaries on each wing during molt, and lose weight to have a wing-load almost the same as when they are full-feathered.

Here are the 32 species seen by 38 observers:

Wild Turkey 12
Mourning Dove 1
Vaux's Swift 2
White-throated Swift 2
Anna's Hummingbird 3
Turkey Vulture 3 makes it official!
White-tailed Kite 1
Red-shouldered Hawk 1
Red-tailed Hawk 1
Acorn Woodpecker 3
Downy Woodpecker 4
Nuttall's Woodpecker 2
Hairy Woodpecker 1 a Picidae Grand Slam!
Pacific-slope Flycatcher 1
Black Phoebe 1
Hutton's Vireo 1
Warbling Vireo 2
Steller's Jay 1
California Scrub-Jay 1
Common Raven 2
Chestnut-backed Chickadee 12
Red-breasted Nuthatch 1
Pygmy Nuthatch 6
Brown Creeper 1
Bewick's Wren 3
Wrentit 1
Dark-eyed Junco 7
Song Sparrow 2
California Towhee 4
Townsend's Warbler 4
Hermit Warbler 3
Western Tanager 1

Best of Boids!

Alan Kaplan

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