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In early March, just north of Haystack Landing and across the Petaluma River from Shollenberger Park, giant eucalyptus trees stood leafy green but devoid of any apparent life. Several weeks later, from across the river, white spots could be seen in the foliage – Great Egrets had started to return to nest for the fourth year in a row. Shollenberger’s heron and egret colony is a successor to a long-established colony located near the wastewater treatment ponds off Lakeville Highway. In 2003 a pair of immature Golden Eagles set up residence near the colony at a critical time, when nest building had just begun, and scared all the birds away. Since then, there has been no nesting at that site. Some of the displaced birds established the Shollenberger colony. While the treatment pond colony included many Great Blue Herons and Double-crested Cormorant nests, for some reason the new colony has been predominately occupied by Great Egrets. PWA docents Bob Dyer and Len Nelson have been tracking the activity of this new colony for the Cypress Grove Research Center of Audubon Canyon Ranch, which is developing an atlas of all heron/egret colonies in the Bay Area. The research center calls the Shollenberger colony, “Colony #121”. Once the birds start to arrive in mid-March, Bob and Len take scopes, paper, and pen to the viewing site. Each nest is given a designation while identifying the species occupying it. Every two weeks until late June, they watch for the emergence of chicks. In 2006 there were 46 active nests, most of which had chicks. This year, three out of four active nests were occupied by Great Egrets. There were also two Great Blue Heron nests with the balance being Snowy Egret nests. Ultimately, about five out of six of the 69 chicks were Great Egret offspring. Some colonies in the Bay Area are favored by other species, but for some reason, the Great Egrets like Shollenberger. The egrets are slender, long-legged birds over three feet tall but weighing only about two pounds. They raise up to four chicks, but the average nest usually has two-three chicks. Incubation takes about 27 days, and the young stay in the nest for about ten weeks – some of them will still be there in early August. When the chicks get large enough, both adults leave the nest to search for food. During this time you can often hear the young calling out to be fed. A healthy colony suggests a healthy environment, and the Shollenberger colony has been devoid of predation or major disturbance since its onset. That could change in the near future. Dutra Materials, which owns the property on which the colony’s trees grow, has proposed an asphalt plant close-by. The plan has met some opposition because of potential air, groundwater, and noise pollution as well as danger to the colony. An environmental impact report is being done on the project and should soon be available in draft form for further public input. Under the federal law, taking, killing, or possessing migratory birds is unlawful. Eggs, nests, and feathers are also protected. Disturbing nests so that nests are abandoned is also prohibited. Experts recommend a 100-200 meter buffer zone around active colonies. There are concerns that the Dutra project will disturb the colony unless the recommended buffer zone is put into place. In spring of this year, PWA docents took hundreds of local school children to observe the colony from Shollenberger. This provided a wonderful opportunity for them to commune with nature – an important aspect of growing up which is often missing from the lives of today’s children. Let’s hope the Great Egrets continue to return (along with the other nesting species) so that the children and all of us can continue to enjoy observing them. Recently, Audubon Canyon Ranch has published a 270-page journal available on their Web site www.egret.org/atlas.html that summarizes the activity at all Bay Area colonies, including the one at Shollenberger. Here are a couple of paragraphs taken from this journal: The slender, poised profiles of foraging herons and egrets are distinctive features of wetland and shoreline ecosystems. To many observers, these conspicuous birds signify the presence of potentially diverse and healthy wetlands worthy of protection. Consequently, herons and egrets are frequently used as symbols of wetland conservation…Such recognition is well substantiated by the ecologically important roles they play. As important predators, herons and egrets are sensitive to subtle changes in ecosystem productivity, hydrology, and vegetation, and (although their responses are not completely understood) they are widely recognized as indicators of processes that sustain or threaten wetland ecosystems…The work presented here complements efforts to protect and restore wetland feeding areas by providing detailed information that could be used to protect heron and egret nesting colonies…. [Page 2-3]. The goals of the atlas are to (1) provide a protocol for intensive regional monitoring of heronries, (2) develop current and historical perspectives on the regional, subregional, and local status of herons and egrets with regards to patterns and trends in their nesting, abundance and reproductive performance, and (3) consider regional, subregional and local implications for conservation…The results are based on field observations conducted over the last 15 years and additional data available for previous years as far back as 1967 (38 years).
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