OAKLAND (CBS SF) – Oakland residents say rare birds were slaughtered during an Oakland tree-trimming project on behalf of the downtown U.S. Post office.

Black-crowned night herons are rare and protected by law, yet can be seen frequently on the streets of downtown Oakland, as are the droppings from the 2-foot tall birds. They have also been known to leave a mess on Post Office trucks. The city has trained work crews to leave ficus trees alone during the spring nesting season, but the USPS hired a 3rd party crew called Campos Tree Service to trim some branches.

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The person in charge of the operation told KPIX 5 that it was an accident, and he was to blame.

“We are human beings, and we all make mistakes, and I am fully responsible for it.  If I have to go to jail for that I will be more than happy to do it, because we all make mistakes,” said Ernesto Palido, a tree trimmer who borrowed the Campos truck to do the job.

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Neighbors feared the birds living in four trees were “fed to a woodchipper” in what witnesses described as an “appalling” massacre to a valued part of the ecosystem.

It was not immediately clear how many birds died in the woodchipper. Concerned residents phoned in complaints to police, who ordered the trimming stopped.

“The public was incensed, rightfully,”  Oakland supervising naturalist Stephanie Benavidez told the Chronicle.

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Several birds were rescued and brought to International Bird Rescue in Fairfield.