GGAS First Friday Birdwalk, July 6, 2018 Tilden Nature Area

Alan Kaplan

Jul 6, 2018 8:30 AM - 11:30 AM

Golden Gate Audubon Society First Friday Bird Walk, July 6, 2018, Tilden Nature Area, to Jewel Lake and back again.

This month is the 100th anniversary of the birth of Chandler S. Robbins, senior author of The Golden Field Guide to Birds of North America (1966 and revised editions) [other authors were Bertel Bruun, a neurologist, and Herbert Zim, a science educator who introduced science laboratory exercises for elementary school students and founded the Golden Guide series of books; the artist was Arthur Singer, who created camouflage for US "ghost armies" in World War 2].

Robbins founded the Breeding Bird Survey of North American birds in 1966; the BBS compared to eBird-ing and Bird Atlasing was the topic today. There is a 25 -mile route for the BBS starting at Pinehurst Road and Valle Vista in Moraga that goes along San Pablo Dam Road and (I think) past the Reservoir and up Castro Ranch Road. This route has been done since 1972, and, though some years have been missed, it was done in 2017. BBS routes involve 25 stops, at half mile intervals, and an observer who looks and listens for 3 minutes at a time, to identify all the birds heard or seen. There are about 4000 routes in North America, not all are done every year. The data for 1985-1991 was analyzed for 450 species of birds and published as The Summer Atlas of North American Birds (Price, Droege and Price, 1995). We compared eBird species abundance "heat maps" for Barn Swallow, Blue-winged Teal and Western Tanager to the 1995 publication and they were very similar.

Take-away lessons from recent eBird publications are: birders improve the more they bird (they submit more checklists with more observations), and birders should add numbers and effort (time in the field and distance travelled) to improve accuracy of predictive maps. Evaluating the accuracy of "citizen scientist" efforts supports the idea that contributions by non-academic ornithologists are important, useful, and relevant. Happy 100th birthday to Chandler Robbins!

Here are the 30 species (+1 other taxa) seen by 39 observers:

Mallard 5 adult female and 4 juveniles
Wild Turkey 3
White-tailed Kite 1 flyover
Red-shouldered Hawk 1
Mourning Dove 4
Anna's Hummingbird 1
Downy Woodpecker 1
Western Wood-Pewee 1
Pacific-slope Flycatcher 1
Black Phoebe 2
Hutton's Vireo 1
Warbling Vireo 3
California Scrub-Jay 1
Common Raven 1
Barn Swallow 1
swallow sp. 1
Chestnut-backed Chickadee 1
Red-breasted Nuthatch 1
Brown Creeper 1
Bewick's Wren 1
Wrentit 1
Swainson's Thrush 7
American Robin 3
Wilson's Warbler 5
Dark-eyed Junco 3
Song Sparrow 2
California Towhee 1
Spotted Towhee 4
Black-headed Grosbeak 3
Purple Finch 2
Lesser Goldfinch 3

Best of Boids!
Alan Kaplan

Join to automatically receive all group messages.