Is there an Animal Shelter or Vet near you? If so, get her in one or the other and have her scanned for a chip. If she has one, that may lead you to her owner.

We adopted a wandering stray this winter. But first I put notices in mailboxes of nearby homes; in grocery stores; in Vet's offices and at the Humane Society. Nothing worked, so Red now belongs to us.

Good Luck - Matilda sure is a pretty thing.