Birding Petaluma Wetlands Through the Months: December

by Dec 4, 2017Birds, Peter Colasanti

From: Peter Colasanti

December, the darkest month, feels like the coldest. Well it’s also the birdiest one in the Petaluma Wetlands, with 144 species logged since 2005 for the month. It only feels bleak to those of us who live here, to the north it’s colder and darker still and to migratory wetland birds it’s a frost-free paradise.

The big influx includes a lot of species that permit easy study. Two dozen types of waterfowl may be found loafing on the ponds of Ellis Creek, Shollenberger Park and on the Petaluma River. In addition to the dabbling ducks, divers appear now, like Scaup, Canvasbacks, Goldeneye and Ring-necks. Watch for stray Snow or Ross’s Geese joining flocks of Canadas, Greater White-fronts may show up in a small flock, rarely even native Tundra Swans, though the Mutes typically bully them out when they do visit. Five species of grebe have been found and 19 shorebirds too. Expect lots of Dunlin to dominate the peep flocks, any dowitchers seen are most likely Long-bills, though they were locally in short supply last year.

Gulls (Oh no!) become a dominant feature now, with 10 possible species. Just this November Noah Arthur confirmed the presence of “Tamyr Gull” at Shollenberger, a bird he’d first reported there last season. The taxonomy on this one’s a little murky, it’s presently considered a subspecies of Lesser Black-backed Gull. This particular individual shows fairly bright yellow legs, a dark eye, and is built like a slightly larger California Gull: long wings and slender overall, but with a very dark mantle and very little white in the wing tips. Right now, there’s also lots of Herring Gulls around and quite a few Iceland Gulls. Note that Iceland is what we’re calling Thayer’s Gulls now that the two former species have been “lumped” into one. Feel like you don’t know anything about gulls? Well it looks like the experts are still trying to get them straightened out too. So, take heart and take a look at them on the central pond, early morning and late afternoon works well.

With the warming of the climate we’ve observed an increase in wintering swallows. There seems to be a core flock of Tree Swallows centered in the delta which spins off small flocks into our area occasionally and in some years, there’s an admixture of Violet-greens, this is one such year. If ever you notice a lot of swallows in winter, keep looking above them, White-throated Swifts often feed above them.

Don’t forget what December’s really about: Christmas Bird Counts! Here we’ve got the Cheep Thrills on Thursday, December 14 and Sonoma Valley, which takes in Allman Marsh south to Tolay, on Friday the 29th. To join in on either send an email to the area leader at [email protected]


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