With fistfuls of colorful sidewalk chalk and stencils of black-crowned night herons, artists and bird lovers around Oakland, California, hit the sidewalks to prevent a repeat of a gruesome event last year.

Every spring, bird enthusiasts and nature lovers remind people to avoid trimming trees, or to be extra alert when cutting down trees. Unfortunately, not everyone pays attention, including the United States Postal Service.

San Francisco Gate reported, "Officials at the downtown post office ordered nearby trees trimmed Saturday because nesting birds were defecating on the mail trucks. The result, witnesses said, was a feathery massacre that ended with nests — and baby birds — fed through a wood chipper, hysterical neighbors protesting in the street, and a call to Oakland police officers, who ordered the trimmers to stop."

While no baby birds were actually fed through the chipper, five chicks were injured after falling some 25 feet. They were taken to International Bird Rescue for care and rehabilitation. The incident caused an uproar and was even reported in the New York Times. As one op-ed writer wrote on KCET, "Black-crowned night herons are not inconspicuous creatures. The adults are two feet tall and noisy. The chicks are about half that size and, when hungry, even noisier. The trees being trimmed Saturday were less than 30 feet tall. If you can miss a bunch of noisy foot-tall birds sitting in a tree that's only 25 feet tall, you almost certainly aren't alert enough to be operating a chain saw."

Oakland residents were understandably horrified when they witnessed the event, and this year they are making a preemptive effort to raise awareness of the black-crowned night herons and they're nesting habits. And they're doing it with a beautifully artistic flare. This video of the event is sure to put a flutter in your heart:

Oakland Herons Art Flash Mob from Golden Gate Audubon Society on Vimeo.

According to Golden Gate Audubon, "About a dozen artists descended on 13th and Alice Streets just after daybreak last Friday to create the drawings. While the trees overhead thrummed with constant chirps, clicks, gurgles, and squawks, the sidewalks filled with beautiful color images of herons and egrets."

The black-crowned night herons started nesting in downtown Oakland only a few years ago. They usually nest at the nearby Lake Merritt bird sanctuary, but they've moved into the city due to either a growing double-crested cormorant population or that they prefer the leafy ficus trees lining the downtown streets, or a combination of these and other drivers.

Either way, it's an illustration of the factors at play on the species around the Bay Area. While not endangered, the herons are facing a rapid decline from habitat loss. They are also loved by (most) city residents, despite the noise and mess they create during nesting season. 

Downtown Oakland is now home to more than 45 nesting pairs of black-crowned night herons as well as snowy egrets. The art flash mob is making sure residents understand that their feathered neighbors are an important part of the ecosystem. So unless you're going to be extra, extra careful, keep the tree pruners and chain saws locked in the garage until winter. 

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Jaymi Heimbuch ( @jaymiheimbuch ) focuses on wildlife conservation and animal news from her home base in San Francisco.

Flash mob paints Oakland's sidewalks to protect urban nesting herons
After last year's traumatic nesting season, bird lovers are creatively increasing awareness of night herons.