By Kiet Do

MENLO PARK (CBS SF) — A crew working on a home in Menlo Park got quite a surprise Tuesday morning when the removed a mural from the side of the house.

Nestled behind the mural was a colony of 83 Mexican free-tailed bats.

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“A group of workers hired by the home owner were preparing to power wash the side of the house,” said PHS/SPCA’s Communications Manager Buffy Martin-Tarbox. “They removed a mural of St. Francis attached to the side of the house when they noticed a large colony of bats that had been nesting behind the mural.”

As the bats began tumbling to the ground, the startled workers quickly called animal control.

“When the bats started to fall to the ground, the workers called us for assistance,” Tarbox said. “Our staff quickly arrived and were concerned the bats may have been injured so we carefully scooped them up and brought them to our wildlife center for evaluation.”

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The bats were given oxygen at the wildlife center and put them into incubators to help with circulation and increase their body temperature. They soon were healthy enough to be were returned to the wild Tuesday night.

Wanting to make sure the bats were comfortable with their surroundings, they were released near the Menlo Park home. Many returned to the mural.

“The irony of these bats being found behind a mural of the patron saint of animals was not lost on us,” said Tarbox.

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Mexican free-tailed bats are native to California and are a species of special concern in California as a result of declining populations. They are medium size bats, on average 3.5 inches in length. Their name is derived from the size of their tail, which is almost half their total body length.