Look up “colonial nesting” online and you will likely see a picture of great and snowy egrets nesting together. And if you live in Alameda you probably have heard of or seen our nesting egrets on Bay Farm Island. The egrets have been nesting here for over 15 years. The two species can often be seen foraging together along many of our waterways. including the Alameda lagoons, Crab Cove, Crown Beach, the Elsie Roemer Bird Sanctuary, and Martin Luther King Jr. Regional Shoreline.
You will hear the croaking and squawking of adults and the clicking, clacking, not-quite-chirping calls of the hungry chicks. The chicks call repeatedly, hoping to get fed. The adult is stimulated to bend down, allowing the chicks to grab its bill, open wide, and receive regurgitated food that consists mainly of fish but could include insects, crustaceans, amphibians, and rodents. Both species catch many fish when abundant. Great egrets generally move slowly through the water or patiently wait, while the snowy egret is often more active, crouching, jumping, and running after prey. The snowy egret often shakes its yellow feet using them as a lure to attract prey.
It is well known that the Plume Trade in the late 19th and early 20th centuries nearly caused the extinction of herons, great egrets, and snowy egrets. The exceedingly beautiful breeding plumes of both great and snowy egrets became a must-have for the growing middle class. And as the middle class prospered, so did the market for lavish hats and other ornamentation. Aigrettes became fashionable in both women’s and men’s apparel. This hunger for bird feathers of various species—not just egrets—led to many millions of birds being killed, leading the National Audubon Society and other conservation organizations to join ranks and advocate for laws protecting birds. One of the results was the landmark Migratory Bird Treaty Act of 1918, which provided broad protections for non-game birds.
Ardea alba, the scientific name for the great egret, and Egretta thula, the snowy egret, are no longer threatened with extinction. Although this is great news, it is our continued concern and responsibility to maintain the health and stability of these beautiful birds as well as other avian species. Roger Tory Peterson, in his Second Edition to A Field Guide of Western Birds, lists the great egret as the common egret, describing it as, “A large, slender white heron with a yellow bill (orange when breeding). Legs and feet black.” His description of the snowy egret reads, “Note the ‘golden slippers.’ A rather small white heron with a slender black bill, black legs, and yellow feet.”
It’s interesting to note that the scientific names of both birds have evolved since the time Peterson wrote this guide. Egretta is the French diminutive of aigron, meaning heron while thula was a misnomer from a Chilean naturalist, Juan Ignacio Molina, who in 1782 named the snowy egret after the black-necked swan. This leads one to ponder Carolus Linnaeus, taxonomy, and binomial nomenclature. Think of genus and species, how these are arrived at, and you have a good start to understanding the ‘who, what, when, where, why’ of naming flora and fauna. And sometimes misnomers stick for centuries. Taxonomy is the branch of science concerned with the classification of organisms. Linnaeus developed binomial nomenclature to disambiguate the identification of plants and animals. This allowed precise identification of a species regardless of language, geographical location, or regional idiosyncrasies.
Incubation of great egret eggs takes 23 to 27 days and they commonly lay between one and six eggs. The chicks can leave the nest at 21 to 25 days but can’t fly until they are six weeks old. Snowy egrets incubate their eggs for 20 to 24 days and have a clutch of two to six eggs. Snowy egret fledglings can fly at about 30 days old. Both species are monogamous and can live to be 15 to 18 years old.
Great egrets have a wingspan of 51 inches, are 39 inches tall, and weigh 1.9 pounds. Snowy egrets have a 41-inch wingspan, stand 24 inches tall, and weigh 13 ounces. The three tall wading birds we see regularly in the Bay Area, from largest to smallest, are the great blue heron, the great egret, and the snowy egret. Each one is beautiful and fascinating to observe as individuals, foraging, nesting together, or in flight. Egrets are not cranes. One way to tell the difference is that cranes fly with outstretched necks and egrets fly with necks tucked in.
A great way to learn more about birds is to join one of the many field trips offered by the Golden Gate Bird Alliance (GGBA, formerly Audubon). Even though I consider myself a seasoned birder, I always learn something new on these outings. Plus, it’s a terrific way to get inside information about our local birds, where to find them, and the best time of year to see them.
There is more to birding than identification. Take some time to observe bird behavior. You can do this with any species in almost any locale. For years I had no idea that egrets would hunt something other than fish. Then I met a great egret at the Berkeley Aquatic Park that surprised me with its startling hunting technique. The experience forever changed my mind regarding standard behavior. The bird would stand motionless at the water’s edge and wait for blackbirds to fly into the vegetation just behind it. Then, with astounding quickness, it would turn and take a bird out of the bushes. I watched it do this several times over a couple of weeks. Through the years I have observed egrets and herons take birds, rodents, snakes, rabbits, and lizards. Now, when I see a heron or egret in a field I wonder what is moving about below its feet.
Rick Lewis is a long time member of the Golden Gate Bird Alliance and other environmental organizations. He contributes often to Bay Area and Central Valley birding groups that promote wildlife and habitat conservation.
This article is part of a series written by Friends of the Alameda Wildlife Reserve (FAWR) members, FAWR is a Conservation Committee of Golden Gate Bird Alliance (formerly Audubon). To find out more about birds and GGBA’s free guided field trips, visit www.goldengatebirdalliance.org.
