A fast dog would be a more effective cat deterrent.

Sorry, but trees and shrubs won't stop cats. Our neighbours tried those strips of plastic spikes on top of their fence. That didn't stop the cats either.

Colletia paradoxa ought to do it! ;-)

https://www.smgrowers.com/products/plants/plantdisplay.asp?plant_id=3195

While anchor plant is pretty ferocious in appearance, I doubt it will stop cats :-) Nothing does......they will find a way through, around or over if sufficiently determined to invade. Barberries, cacti, hardy orange (Poncirus trifoliata)........none of these are any deterrent to cats (or most other wildlife, for that matter).

I really think your most effective weapon - outside of a cat aggressive dog - will be some sort of repellant spray.

Thank you, all, for your comments.

No, we will not be getting a dog. We have one cat that is an indoor cat. There is a cat in the neighborhood (no one seems to know who owns it) that will throw itself against our windows if it sees our cat inside. This neighborhood cat has also shredded a window screen, trying to get in. I don't know that this cat is "sufficiently determined to invade" our yard or if it's just too easy to get in, and, hopefully, it will decide that plowing through a dense (or sharp-leaved) bush/tree isn't worth the effort. Oddly enough, it only comes into our yard via that one fence line.

We will definitely look into getting some Colletia Paradox (Anchor plant)!

Whoa! That Colletia paradoxa looks like it has some vicious thorns. Very cool looking. I like it. In someone else's yard.

Keep in mind that if you plant that in your back yard, the annoying cat is not the only creature living there that is going to have to deal with those thorns.

Our cat is strictly an indoor cat, so we don't have to worry about him getting tangled up with that bush/tree! And Hubs and I will know not to mess with it, either. :-)

We want the protection along the Southeast fence. Strangely enough, that's the only area where this other cat accesses our yard. Our lot is oddly shaped because we're right at the curve of the street. (It's an L-shaped cul-de-sac.) Because there is a creek that runs behind our lot, there aren't any houses close to us in back. You can't build within 60' feet of the creek, and we're about 80' from the creek at the closest point. And that dang cat never comes over the fences between us and the creek - only over the fence between us and that one neighbor (and, no, it's not that neighbor's cat - they don't like it, either.)

The cat wears a collar. No tag on the collar, though, as far as we can tell.

Drats. That does add another level of difficulty.

The cat will find another way to get in if it really wants to.

You could befriend it by feeding and capturing then take to a shelter.

Chances are the owner doesn't know and doesn't care about its wandering.

Perhaps spray it with the garden hose. A couple times should be enough of a deterrent.

Or even a hose with a motion detector.

I agree that sprinklers with motion detectors would be most effective. But they would detect you and your husband's motion too...

I would snap a picture of the cat and post it on your nextdoor website.

If the problem is truly serious, it may cost less $$ to set an outdoor motion detection camera to get a photo for that purpose.

Where I live in SoCal, there really is no such thing as a "stray cat", well, for longer than one night, due to coyotes.

Additionally, it may seem to you that the cat enters only over that side of your yard, however, if you make that entrance more impassable, the cat may find another way in. So, planting vicious thorny bushes probably won't work, even if it works (if you see what I mean).

If you can catch the cat, you can take it to a local vet for a microchip read. And then present the owners with a bill for your screen.

Rather than trying to keep the cat out of your yard you might have more success keeping it away from the windows you describe. Cat Repellent

There is also a device called Mini ScareCrow but I don't know if it can be used outdoors.

If our cat sits on the sill of the dining room window, the neighborhood cat will throw itself against that window. Same thing if our cat is sitting on the sill of the living room windows, or the family room windows, or the breakfast nook windows. Sigh.

I'd vote for sprinklers set to a motion-sensor. A few encounters in that area would be quickly learned.

We have no sprinklers in the front yard. It's all drip irrigation (all plants - no lawn). And we're redoing the back yard, and I don't think we're going to have sprinklers over in that area (we have a big back yard by California standards - see image, above).

I think otcay is talking about the motion-sensor sprinklers such as the scarecrow. You only need a hose and spigot and set the water low. They've worked well for me with deer and chipmunks, so I imagine it would also work with a cat. I used to spray water at mine to keep it off things and generally, once sprayed it wouldn't come back. I think it's wrong to assume the the owners don't care what happens to their cat unless it really looks neglected so some of these suggestions seem abit over the top. However, a picture posted to a local website could help ID the owner and maybe you could talk to them and figure something out. I also think the issues with the planting for other animals was meant to indicate animals other than your own such as wildlife, etc., but they may not be a problem.

My cat climbs to the middle of barberry bushes for fun, so thorns won't work. Cats hate water, loud noises, citrus and mint.

Most cats don't like walking on rocks, all my indoor plants have a 2-3 inch topping of decorative gravel that keeps my guys away.

SSScat cat deterrent works if the can is located in a sheltered area.

If you have a hose spigot outside a temporary motion detector sprinkler should be easy to set up. Not my favorite solution, but may be necessary.

Good Luck

April

As others have mentioned, the sprinkler isn’t a regular one, it is one with the purpose of being a critter deterrent. Since it is motion activated, it only sprays when a critter is nearby. So you could set it up in the vicinity of the window your cat likes, and it will spray the unwanted visiting cat when it gets near. It is aversive to the visiting cat, but ultimately harmless.

"So you could set it up in the vicinity of the window your cat likes, and it will spray the unwanted visiting cat when it gets near."

I wrote, above, "If our cat sits on the sill of the dining room window, the neighborhood cat will throw itself against that window. Same thing if our cat is sitting on the sill of the living room windows, or the family room windows, or the breakfast nook windows."

There are at least 6 windows that would need to be "protected" with such a sprinkler.

We're just trying to help. The scarecrows can be adjusted for the width of their arc so you could possible place it so they wouldn't get so close to your windows or you may need more than one. Despite popular opinion cats can be trained and spraying with water generally works well.

I’m curious about why this cat is so obsessed with your cat.... Does your cat happen to be an unspayed female and the invading cat an unneutered male...?

DH and I volunteer at a local service dog training facility. In spring when some of the not-yet-spayed young female dogs in training go into heat, coyotes start hanging around in the park behind the fence behind the parking lot. Clearly ‘in heat’ scent travels well in air! Could that be a factor in this cat case?

Havaheart trap + 50 bucks and call animal control when you catch it.

Most cats run on a tight schedule, you can set a clock by it. They can be seen walking across the same area at the same time every day. Since your yard to close to water, kitty is probably on his way to or from the stream. Streams mean hydration and fun. Kitty comes through your yard for a reason, Food? Water? Shade? Hiding place on the way to another destination? Birds and the bees as mentioned above.

If Kitty enters your yard at the same place THAT would be the spot to put the water sprinkler. I would put an area of small gravel and citrus tree or bush.

Good luck

April

"We're just trying to help."

Yes, I know, and I do appreciate the suggestions. I just don't think a sprinkler would work in our situation/yard.

If the cat permits, maybe tie a note to the owner to its collar? Which may not solve the problem but at least you could try letting the owner know.

Is there some kind of reflective film you could put on the windows so you and the cat could see out, but the offending cat can't see in?

"If the cat permits, maybe tie a note to the owner to its collar? Which may not solve the problem but at least you could try letting the owner know."

We'd have to trap the cat in order to do this, as the cat will turn and run if you try to approach it.

"Is there some kind of reflective film you could put on the windows so you and the cat could see out, but the offending cat can't see in?"

Because our cat is strictly an indoor cat, we and the cat like to (when the weather is decent) open the windows so he can sit on the sill and enjoy the fresh air. Reflective film wouldn't help when the windows are open and the cat is sitting in front of the window screen.