Being an island with many inland waterways, Alameda is home to a variety of water birds, including several species of herons and egrets. Many of these species are frequently seen by birders as well as casual observers, as they walk the numerous trails along the waterfront and lagoons. Even while driving along the street and crossing one of Alameda’s bridges, herons are a common sight.
Bay Farm residents are familiar with the great and snowy egret colonies near the lagoon. With their spectacular white plumage, they are hard to miss. Great blue herons, sometimes mistaken for cranes, are not as numerous, but standing four feet tall, they are a known presence at the waterside parks such as Crab Cove and Elsie Roemer Sanctuary. A smaller cousin, the black-crowned night heron, is famous for its large nest colony in downtown Oakland.
In addition to the well-known herons, there is another shy, secretive member of the family, rarely seen but always around, skulking along the edges of the bay or other bodies of water, hiding in the reeds, or just sitting unnoticed in a tree overlooking the water. This is the green heron, a small, plump heron with short legs. Colors that blend in with its surroundings make it inconspicuous and hard to spot. At 18 inches long, it is the smallest heron with the exception of the rare least bittern.
At first look, you may wonder what is green about the green heron. The most prominent color is the deep chestnut neck and dark cap, but if you get a close look in good light you can see that its back is laced with green and blue-gray. Its food is primarily small fish, which it catches by standing still at the water’s edge waiting patiently for a fish to come within reach, then quickly snatching or spearing the prey with its long heavy bill.
In the past, I would come across a green heron in Alameda maybe once or twice per year, often on the northern waterfront at Shoreline Park near Marina Village. This changed last year when I was part of a team of Friends of the Alameda Wildlife Reserve members monitoring the bald eagle nest at Corica Park Golf Course. As we were checking on the Eagles every day, we also noticed that a green heron almost always made a brief appearance, somewhere along the waterways. When we began leading field trips there, sponsored by Golden Gate Bird Alliance, the heron was often one of the highlights.
On one of our field trips this spring, we were lucky enough to spot a green heron carrying a stick, a sure sign of nesting behavior. Green herons typically lay three to five eggs in one or two broods per year. They incubate for 19 to 21 days, and both adult herons feed the chicks until they fledge three to four weeks later. By closely watching the bird, we were able to find its nest in a Eucalyptus tree next to a canal. The nest was so well hidden that only a small corner of it could be seen from the ground.
On a later field trip, we found the nest again. Standing next to it was a fuzzy brown fledgling heron, inconspicuously blending in with the surrounding branches. Searching with a scope we found two more fledglings on nearby branches.
Another pair has been observed at Crab Cove near the little pond, but that nest was apparently not successful. Like many bird species across the United States, green heron numbers have declined by about 50% over the last 30 years. It is good to see some breeding success here in Alameda, and hopefully our Corica Park heron family will continue to thrive.
Doug Henderson has been birding Alameda and the surrounding area for many years and is a member of the Golden Gate Bird Alliance.
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 trips see www.goldengatebirdalliance.org