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Marin’s Booming Bird Populations: Three-quarters of a Century of Avifaunal Expansion
February 11, 2021 @ 7:30 pm - 9:30 pm
Speaker: Roger Harris
Host: Doug Waterman
Date: February 11, 2021
Start time: 7:30 PM
End time: 9:30 PM
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Many of our common Marin County birds, whose abundance we now take for granted, were rare or absent only three-quarters of a century ago. Since the beginning of the Southern Marin Christmas Bird County in the 1970s, for instance, Red-shouldered Hawk detections have increased tenfold. Habitat restoration and maturation, conservation efforts, and cultural changes in the behavior of individual bird species have all contributed to shifting – and, for Marin, generally increasing – bird populations.
Snowy Egrets, Great Egrets, and Great Blue Herons, which had been extirpated from the Bay Area, returned in the mid-twentieth century. Black-necked Stilts were first recorded nesting in our marshes in the mid-1960s, followed by American Avocets in 1984. In 1996, Forster’s Terns nested in Corte Madera Shorebird Marsh for the first time in Marin County.
The dean of California ornithology, Joseph Grinnell, wrote in 1915 that the Ridgway’s Rail “seems destined to early extinction.” The rail is the logo bird of the Marin Audubon Society and conservation advocacy efforts have made Grinnell’s prediction of a century ago at least premature.
Our speaker, Roger Harris, will unpack the evolving dynamics of avifaunal population change using data from Christmas Bird Counts, the Marin County Breeding Bird Atlas, and a variety of other sources. Roger is a Certified Wildlife Biologist and a longtime member of the Marin Audubon Society. Once the pandemic resolves, he hopes to return to leading international eco-tours for the Oceanic Society.
Photo courtesy of Roger Harris