Gaze out to San Francisco Bay, and chances are you'll see herons, egrets, ducks and dozens of other familiar bird species.
But this summer hikers and weekend bird-watchers are all aflutter about a new, and distinctly exotic arrival: a flamingo.
That's right. A flamingo. And it's not made of plastic.
The elegant pink bird -- normally found in tropical areas thousands of miles from San Francisco Bay -- has been spotted several times, and photographed swimming off the Sunnyvale shoreline over the past month. Before that, another flamingo, probably the same one, was seen off the Hayward shoreline as far back as Thanksgiving.
"There's a buzz about it," said Larry Campbell, of San Carlos, who spotted the flamingo last week while hiking on the earthen levees near the Sunnyvale sewage treatment plant. "When you tell people, you see their jaws drop."
Where did it come from? Nobody knows.
Officials at the San Francisco Zoo, Oakland Zoo and other Bay Area wild animal facilities say they aren't missing any lanky pink residents who sleep standing on one leg.
"All of ours are here," said Cathy Keyes, a lead zookeeper at the Oakland Zoo.
After looking at photographs taken recently of the distinctive, long-legged bird off Sunnyvale, Keyes said it is a lesser flamingo. The Oakland Zoo has 16 of them. They are the smallest of the six species of flamingo worldwide, weighing about 6 pounds and standing 3 feet tall. The birds eat blue-green algae and occasionally brine shrimp, both of which San Francisco Bay has in large numbers.
Lesser flamingos aren't exactly what you'd call locals.
They normally inhabit Western Africa, along the coastal shoreline of Nigeria, Ghana and Ivory Coast as well as much of southern Africa, including Mozambique, Namibia and South Africa, and some parts of northeast India. The flamingos, which can live to be 50 years old, breed primarily in the Rift Valley lakes of East Africa in Ethiopia, Kenya and Tanzania.
"I don't think this bird came from Africa on its own," Keyes said. "I imagine it is somebody's escaped pet."
Reports of flamingo sightings have gone as far back as 2010, when several birders said they saw one near Coyote Hills Regional Park near Fremont. Last November, a lesser flamingo suddenly turned up just north of the San Mateo Bridge, in freshwater marshes along Hayward Regional Shoreline park.
"Some of the rangers named it Pinky," said Linden Rayton, a naturalist with the Hayward Shoreline Interpretive Center. "It seemed perfectly happy when it was here. It never seemed to be in danger. It never seemed to be lonely."
The bird didn't have a tag on its leg, she said. Nor does it appear that its wings were clipped, a common tactic used in zoos to keep birds from flying off. Those are clues it may have been part of a private owner's collection.
"I saw it fly several times," Rayton said. "You can't get close to it. It flies away very quickly."
Although the bird hung out in the Hayward marshes for seven months, it suddenly disappeared last month.
That's the same time the flamingo turned up in Sunnyvale, in the ponds next to the sewage treatment plant.
A Mountain View software engineer, Bilal al-Shahwany, photographed it on June 23, while walking on a public hiking trail along the earthen levees about a mile from the Sunnyvale Water Pollution Control Plant.
"I was actually going there looking for it," he said. "I saw a guy on a bicycle who said, 'Did I just see a flamingo?' I said, 'Yes, yes.' He said, 'Nobody is going to believe me.'"
Lesser flamingos are not endangered. And although the bird has food on the bay, it could face a threat from predators, like coyotes, foxes or raccoons. Keyes, of the Oakland Zoo, said if nobody claims it, the zoo may be interested in bringing it to the zoo to join its other 16. After all, flamingos are social birds and live in groups of thousands in the wild.
The pond the flamingo has been spotted in is 440 acres and used to treat sewage as part of Sunnyvale's wastewater process, said Sunnyvale city spokeswoman Jennifer Garnett. After sewage comes into the treatment plant, it is treated, and then moved to the pond, where bacteria and algae break it down before it is eventually discharged into the bay. The nutrient-rich environment provides habitat for lots of birds, Garnett said.
As for the flamingo, workers at the plant haven't noticed it yet, she said.
"It's pretty exciting," Garnett said. "Maybe we should put out some garden gnomes so he'll feel at home."
Paul Rogers covers environmental issues and resources. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN.