Golden Gate Audubon First Friday Bird Walk February 3, 2017 Tilden Nature Area


Alan Kaplan
 

Friends!

Tilden Nature Area, Contra Costa, California, US
Feb 3, 2017 8:30 AM - 11:30 AM

Golden Gate Audubon Society First Friday Birdwalk, February 3, 2017. Tilden Nature Area, to Jewel Lake and Back Again! Our theme today was dual: Groundhog Day, and Mixed Species Flocks.

Two take-home lessons of Groundhog Day: The stars above us tonight (early February) are the star patterns of the Vernal Equinox sky of 3500 years ago, when (French folklorists tell us) there were spring celebrations that included The Bear (as Ursa Major, our Big Dipper). The "six more weeks of winter" (now closer to seven) marks off the time since today's star patterns were those of the spring: "precession of the equinox" (due to the Earth's axis wobbling in a 26,000 year cycle) causes the stars to appear a week earlier each 500 years. The Bear emerges from its hibernation, expecting a spring event, finds it is still winter, and goes back to sleep. The French say it sleeps for 40 more days, the Germans say the badger (another winter hibernator) sleeps for 4 weeks. German immigrants brought their folklore to Pennsylvania, and transferred their many early-February traditions to the groundhog. 2017 was the 131st year of the Gobbler's Knob event in Punxsutawney, PA - the groundhog saw its shadow: six more weeks of winter! See H. Newell Wardle, Note on the Groundhog Myth and its Origin, Journal of American Folklore, 1919, vol. 32, pp 521-522 (it is available on line!). Thank you, Professor Alan Dundes, for this reference!

The other lesson is: Groundhogs wake up early in February so they can have grandchildren. Males go around to the wintering sites of females (who are still hibernating) and cuddle with them, a bonding activity that makes the male familiar when they meet in another month or so (maybe his scent is left in the female's den?). Females are in estrus for only two weeks; ovulation is induced by copulation; gestation is 30 days; and the young are in the burrows for another 20-30 days, then out in the world and on their own soon after. Groundhog young need to have enough time to fatten for hibernation, so the earlier the males wake up from their hibernation, visit females for a "familiarity tour" (they may go to back to hibernate for awhile), and then mate when the females emerge, the better chance their offspring will survive to have offspring. So, the groundhog gets up early to have grandchildren!

New information on Mixed Species Flocks is available on line (you need to hunt around for a free PDF but it is available): Sridhar, H. et al., 2012, The American Naturalist 180(6):770-790, Positive Relationships between Association Strength and Phenotypic Similarity Characterize the Assembly of Mixed-Species Bird Flocks Worldwide. Birds in MSF's are likely to be similar in size and shape, have similar foraging styles, and are often phylogenetically related.  Also, "Like Chasing Tornadoes" by Jack Connor (Living Bird, Autumn 2014. pp 38-39), and "Chickadees in Winter" by Bernd Heinrich (Natural History, March 2015, pp. 30-35) are fun to read, too.
 
Here are the 29 species seen by our group of 18 observers:

Mallard  6
Common Goldeneye  1     female has been here for awhile
Common Merganser  4     females
Wild Turkey  2
Great Egret  1
Green Heron  1
Cooper's Hawk  1
Red-shouldered Hawk  1     fide Patsy R.
Red-tailed Hawk  1
Band-tailed Pigeon  1
Anna's Hummingbird  1
Allen's Hummingbird  1
Northern Flicker  2
Black Phoebe  1
Steller's Jay  3
California Scrub-Jay  2
Common Raven  6
Chestnut-backed Chickadee  5
Bewick's Wren  1
Ruby-crowned Kinglet  3
Hermit Thrush  1
American Robin  40
Yellow-rumped Warbler  30
Townsend's Warbler  1
Fox Sparrow  1
Dark-eyed Junco  3
Song Sparrow  1
California Towhee  2
Spotted Towhee  1

Best of Boids!

Alan Kaplan

Please use my new email address from now on:


Thanks,
Alan Kaplan

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