Feral cat Evidence of Intrusion is mainly linked to the cats territorial instinct. Marking their territory is priority number two (2), after finding food of course, and your yard and garden my show on or more of the following signs of intrusion.
Feral Cat Evidence of Intrusion-Foul smelling plants and objects
All cats spray urine to mark their territory or if they are stressed. The smell is much stronger than human urine and if you smell it once, you will most likely never forget it! Spraying is particularly common in un-neutered males and with most feral cats not neutered, this can be a big problem!
Feral Cat Evidence of Intrusion-Holes dug in gardens and flower pots
Cats will dig in your garden for a couple of reasons. The first being territorial. This is perhaps the most detrimental and unsanitary for you because they will defecate to let any other cats in the neighborhood know that your yard is their territory. Secondly, and much less unsanitary, Feral cats will dig in your gardens to sleep. This is done either to keep cool in the summer or to keep warm in the winter when the air temperature is much cooler than the earth's temperature.
Feral Cat Evidence of Intrusion-Smaller Population of Rabbits
While not a territorial action, a sure sign that feral cats are visiting your yard, or worse have taken up residency in your yard, is the sudden absence of smaller rodents. Rabbits, chipmunks, etc. are often breakfast, lunch or dinner for Feral cats (or your neighbors well feed domestic cat, too!).
Feral Cat Evidence of Intrusion-Scat
Feral cat scat is left not only as a consequence of digestion, but to mark territory as well. Unfortunately, it may end up in your potted plants and vegetable gardens. Cat scat are tubular with blunt ends and look like the photo below:
Feral Cat Evidence of Intrusion-Tracks
Cats are light footed, but they will leave evidence of intrusion in your gardens. Look for these tracks in the soft dirt of your garden beds:
Feral Cat Evidence of Intrusion-Fence and Post Scratches
Cats will reach up and scratch trees and posts in order to show to other cats their size and strength. These are much easier to locate in your home, normally resulting in a scolding towards your pet, but they can also be found outdoors as well. Look for these scratches 18-24" above the base of the tree.
It is clear to see that territorial marking is the culprit for the majority of the many types of Feral cat evidence of the intrusion.