(Courtesy Joe Kovalchick)

A Pennsylvania family celebrating the 12 th birthday of their son got a surprise visit on Sunday when a mama bear with her cub decided to follow in the partygoers' footsteps and go for a swim.

The Kovalchick family, of Shelocta, Penn., was eating outside with birthday celebrants when they saw a bear appear from the woods.

"She was looking for bird feed to eat," homeowner Joe Kovalchick told ABC News. "She walked towards the road and a cub, maybe 10 pounds, popped up behind her."

This particular bear has been to the Kovalchicks' property - located in a woody area a few miles from the town's main road - many times before, according to Kovalchick. Her presence, he said, did not scare the dozen or so partygoers.

"She's been used to us and we're used to her," he said. "It sounds strange that we're not scared of them but we've seen them many times."

That explains why Kovalchick and his family and friends were also not concerned when the bear and her cub reappeared about 50 feet from them just a few minutes later.

By this time the party was done with the food and had moved on to swimming in the family's pool. The mama bear followed suit, leaving her cub on dry ground while she took a dip in the family's backyard pond.

(Courtesy Joe Kovalchick)

"She stayed around 10 minutes and then went back into the woods," Kovalchick said. "It was just a chance [occurrence] that we're having a party and the bears were here at the same time."

Bears are a frequent sight in Shelocta, Kovalchick said, a borough about one hour outside of Pittsburgh, so locals there know to keep their garbage inside and are not surprised if they see paw prints on their front porches overnight.

"We're sort of used to them," he said. "As long as you don't get in their way, they don't bother you, in my opinion."