Rescued egrets, herons take wing at Oakland marsh

A young snowy egret flies to its freedom after being released in the restored march area of the Martin Luther King Jr. Regional Shoreline August 19, 2016 in Oakland, Calif. A young snowy egret flies to its freedom after being released in the restored march area of the Martin Luther King Jr. Regional Shoreline August 19, 2016 in Oakland, Calif. Photo: Leah Millis, The Chronicle Buy photo Photo: Leah Millis, The Chronicle Image 1 of / 7 Caption Close Rescued egrets, herons take wing at Oakland marsh 1 / 7 Back to Gallery

One by one they hobbled out of their cages, wincing in the harsh sunlight that glimmered over a marsh by the Oakland estuary.

The five snowy egrets and three black-crowned night herons flapped their wings, glided over a small bog and landed in the muddy wetland. Rescued from a dangerous life on the streets of Sacramento and Sonoma, they are now free to roam the Martin Luther King Jr. Regional Shoreline.

Their release Friday morning helped commemorate a successful three-way partnership between the Oakland Zoo, the International Bird Rescue and the Golden Gate Audubon Society, whose staff and volunteers saved 21 young herons from injury or death this year in the similarly tough environment of downtown Oakland. Those birds were healed and liberated earlier this summer; the Sonoma and Sacramento birds were among the last to go as nesting season wraps up.

“I call it an urban intervention,” said Cindy Margulis, head of the Golden Gate Audubon Society. She said the birds often nestle in the ficus trees in Oakland’s Chinatown district, where they can fall on concrete or get hit by cars. When birds fall in the wild, they usually land on a soft tree canopy or patch of grass, and can easily climb back to their nests, Margulis said.

But in a busy downtown area, what would normally just be an embarrassing tumble becomes a potential death sentence.

With development picking up in Oakland and more buildings brushing against the birds’ natural shoreline habitat, many of them are migrating downtown and finding “the kind of trees they like,” said Ilana DeBare, the society’s spokeswoman. The wild birds gravitate to Chinatown because it abuts Lake Merritt and the waterfront, where they hunt for fish.

During the spring and early summer, volunteers counted more than 140 nests downtown, mostly along 14th Street and in a cluster of trees at 12th and Harrison streets.

Some of those birds survive and return to the wild, but many face grave harm: concussions from falls on the street, broken wings, malnutrition because they can’t get back up to their nests to eat. Two years ago, tree trimmers lopped off dozens of tree branches near the Oakland Civic Center Post Office, sending nestlings careening to the ground with bruises and fractures.

Last year, Golden Gate Audubon dispatched a team of volunteer docents to educate people about the birds. This year, they teamed up with veterinary experts from the zoo and International Bird Rescue to do triage. When the docents saw birds on the ground, they called the zoo to perform emergency rescues. Zoo staff then shipped the injured fowl off to the bird rescue facility in Fairfield for rehabilitation.

“Some need wing wraps,” said JD Bergeron, who heads the Bird Rescue. “Others just need to be raised and fattened up.”

Each of the eight birds that flew out Friday had an identification band to track its success over time. Most likely they will stay in the Bay Area, Bergeron said; wildlife experts have found the birds nesting on the shoreline seven years after their release.

Yet there is a still a danger that the rescued birds will gravitate to downtown Oakland and roost in the ficus trees that line its sidewalks.

“One of the things Golden Gate Audubon has been working on with the city is to trim those trees after nesting season, so that the birds no longer want to stay there,” Bergeron said. “It’s a concern that we all share — the city doesn’t want dead birds on its sidewalks either.”

Long term, the best solution is to create more sites where the birds can nest away from traffic, DeBare said. Until that happens, she said, Golden Gate Audubon will continue its rescue effort.

Rachel Swan is a San Francisco Chronicle staff writer. Email: rswan@sfchronicle.com Twitter: @rachelswan