The calls of egrets that nest in trees within Google's Mountain View headquarters are louder than the shuttle buses and bikes that pass through campus.
If the migration patterns of egrets at the colony are any indication, more voices will soon join those that are already there.
Six orphaned snowy egrets were released at Charleston Slough on Tuesday, July 15, at the end of a rehabilitation effort that began soon after they fell from trees on the campus earlier this year.
The egrets' release was a collaborative endeavor between city of Mountain View officials, the Santa Clara Valley Audubon Society and the Wildlife Center of Silicon Valley.
According to the Audubon chapter's executive director, Stephanie Ellis, over 40 egret nests are in trees along Shorebird Way within Google headquarters. Mountain View city biologist Philip Higgins said the population is regionally significant and one of the largest within the southern Bay Area.
According to Higgins, both snowy egrets and great egrets have taken up residence at the aptly named Shorebird Way for at least nine years. They typically arrive around March at the beginning of their nesting season and leave around August at the season's conclusion. Snowy egrets have yellow feet and black beaks; great egrets have black feet and yellow beaks and are generally bigger than snowy egrets.
Since the beginning of June, 15 egrets have reportedly been rescued after falling from their nests at the Shorebird Way colony. According to Ellis, many of the falls result from sibling fratricide, in which the older, more robust egret chicks push their younger and weaker siblings out of the nests. Ellis said that sibling fratricide is a natural behavior, given the limited availability of food.
"It ensures that at least some of your chicks will survive rather than having to feed them all at once because they're developing," Ellis said.
Google officials who spot fallen egrets notify city officials, who, with Audubon representatives, determine whether the egrets can stay on site or require rehabilitation.
"If they're uninjured and they can fly, we leave them alone," Higgins said.
If the egrets are young, injured or otherwise vulnerable, either the Silicon Valley Animal Control Authority, Wildlife Emergency Service or the Audubon Society transport the birds to Wildlife Center.
At the Wildlife Center, it's determined whether the egrets can be nursed back to health. Of the 15 rescued egrets, two have been humanely euthanized, according to wildlife rehabilitation supervisor Ashley Kinney.
After employees check them for any parasites, the egrets are transferred to a confined area. The center provides medical support the egrets and staff ensure they develop the ability to fly, scavenge and hunt live prey on their own.
"We want them to be fully self-sufficient before we release them," Kinney said.
According to Ellis, the six egrets released last week had temporary bands attached to their legs that will wear down over time.
"Most of the wild population is not banded," Ellis said. "Just to be able to track these individuals as individuals will tell us a lot."
Higgins said that many of the injured egrets city officials pick up suffer broken legs or wings, and that the concrete underneath the trees poses a serious safety hazard. Kinney said that most of the egrets taken to the wildlife center are too young to care for themselves.
"The majority of the egrets that come in are orphaned and only a small percentage are actually injured," Kinney said.
As of July 22, seven egrets remain at the Wildlife Center, according to Kinney. Kinney said she expected more egrets rescued from the Shorebird Way colony to arrive shortly, and she hopes to release more rehabilitated egrets within the next few weeks to make room. Some egrets get transferred to International Bird Rescue Research Center for this reason.
Earlier this year, Google and city of Mountain View officials agreed to close a section of Shorebird Way to motor vehicles at the recommendation of Audubon Society environmental advocate Shani Kleinhaus, according to Ellis. The closure came as a result of concerns that motor vehicles could run over fallen egrets, killing them, injuring drivers and damaging vehicles. Higgins said that one egret at the colony was killed by a motor vehicle last year.
City officials said they hope to re-open the closed section of Shorebird Way in mid-August at the end of nesting season.
According to Higgins, it is unusual for egrets to nest in an urban area like Shorebird Way they typically nest in areas closer to water.
Ellis said she believes the egrets' choice of residence within Google headquarters is an exciting natural anomaly.
"I'm honestly thrilled that these birds nest in such an urban environment because it gives most people who don't even know what an egret is an opportunity to view them up close," she said.
More information about the Santa Clara Valley Audubon Society is at www.scvas.org, and more information about the Wildlife Center of Silicon Valley is at www.wcsv.org.