About four hours after I got the collar on him, his owner texted me. His name is Ollie and he lives on the other side of the complex.
While I'm glad he isn't lost or abandoned, I'm also kind of sad. I was kind of hoping we would be able to take him in. I told his owner that Ollie is welcome to come visit my yard any time he likes. (I suspect he won't be around as much since now we won't be giving him food).
But he can still come for the catnip. And the sunflowers