Tipped or Notched Ear
The tipped ear contributes to the cat's safety as it signals to
animal control officers and neighbors that the cat has been fixed and
is being cared for.
Recognizing Feral Cats
Feral cats who have been altered have a tipped or notched ear.
This is the universal sign of a fixed feral cat.
Here are a few examples of beautiful cats with tipped or notched
Picture courtesy of Fix