The duo attended a weekend bash at Hollywood talent agent Michael Kives’s house, where they were greeted by several special guests: animals from a conservation (including an alligator and a kangaroo!).
“They were really cute,” an attendee tells PEOPLE. “They were standing near each other most of the night, playing with the animals outside.”
When they weren’t checking out the nonhuman partygoers, Perry, 27, and Mayer, 34, “definitely enjoyed each other’s company.”
“They almost acted like they’ve been a couple for a long time,” adds the source. “It definitely didn’t seem like a new relationship.”
Rumors of a romance first swirled when they were spotted last week leaving a dinner date in Los Angeles.
Perry – who split from husband Russell Brand last year and was last linked to Florence + the Machine guitarist Robert Ackroyd – told Elle in its September issue that she is “a woman who likes to be courted – strongly.”