OAKLAND (CBS/AP) — Federal officials say no protected birds died in a wood chipper this month as a company trimmed trees outside an Oakland post office.

U.S. Fish and Wildlife spokesman Steve Martarano said Tuesday that investigators made the determination after interviewing witnesses, reviewing a bystander’s video and examining the wood chipper.

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The investigation followed witnesses reporting bird chicks and their nests toppling to the ground and some being ground up in the wood chipper outside the post office in downtown Oakland on May 3.

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The Oakland Tribune reports that the finding supports previous statements from Oakland police, the U.S. Postal Service and a contractor who said no birds were killed.

But five young black-crowned herons were hurt after falling about 25 feet from the trees as workers clipped away at branches. The herons are protected species by the U.S. Migratory Bird Act.

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