Yeah, probably! because your cats can only "mark" the interior of their confines. The "outdoor" cats will likely scent mark the posts of your enclosure (to the chagrin of you and your cats). Since a physical "face off" cannot occur and be definitively decided, the posturing will be likely be ongoing, loud, and inconvenient.

That's how animals "work". "Territories" don't allow for vacuums.

Thanks Chelone for the response.

Hmm ... I've been thinking .. very soon I'll start a lil garden just outside the enclosure, so might as well fence that area off too, don't want it ruined by the strays. And maybe a transparent acrylic sheet on top of the cat's enclosure (so no spraying from the top), and as kitty encl will be within the bigger garden enclosure, the strays can't get near it. Or maybe we could separate that portion wth another acrylic sheet? Then if the strays spray the acrylic, would it be easy to remove the odour? Posturing would be on in full swing, I'm sure of that :D

I'm the pariah here, Pranj.. I actually allow my cats unfettered access to the great outdoors. ;)

I have a cat enclosure on my back patio for my 3 cats. Since we installed the enclosure I haven't seen any stray cats on our property. We now have a dog but for several years it was just the cats. Are your cats fixed?

Oh, if only I could allow my cats outside ... there's virtually no traffic around here, but the risk of infection from stray cats is too daunting for me.

Blues, yes, all our adult cats are fixed (Jaz and Coco will be de-sexed before the enclosures are set up).

Your experience is a glimmer of hope for us ... I've already got my hands full trying to get Simba to like Jas and Coco (he hisses and sometimes swats at them, but growling goes on bigtime), I want the enclosures to get done fast so they can have more space to roam around and spend their energy. The stray cat problem is worrying me no end.

What sort of infection are you referring to?

I meant, if they get into fights with strays or anything of the sort. And I always worry about kids injuring animals just for the heck of it. I've seen that happen before to stray kittens. I guess I'm a lil paranoid about these things, and the fact that my cats have always been indoors. Otherwise, this is a good place to let them roam around freely, I mean the traffic part at least isn't a problem.

There are a myriad of infections cats can pass to each other in the "wild", not just from fights, but that can be passed from sneezing via the nasal droplets, using the same "litter" areas and grooming themselves after walking over the areas, and eating from the same bowls (if you feed them outdoors and strays come up at night).
I can tell you, you have no idea how many strays are in your area unless you install a camera on your yard or porch (if you leave any food bowls out).

Of the more serious:
http://www.petcaretips.net/feline_immune_deficiency_virus.html

and
http://ezinearticles.com/?Common-Pet-Diseases-and-What-You-Can-Do-To-Help&id=517457

While there are vaccines against feline leuk., the vaccine is not without risk.

Abscesses are also an issue when cats fight. Cats have some pretty nasty bacteria in their mouths, not to mention the parasites they can pick up while wandering outdoors.

I have an indoor/outdoor cat which we rescued, the things this cat has been through.
When he found us, he was sick with infection. Green pus running from his cheek.
300.00 and surgery to have a large abscess the size of a half dollar removed from his face and a drainage stint.
Fortunately, he's only had minor issues since then.

We're going for the enclosures.

Hmm... would the enclosed kitties be separate from the 'wild' ones with window screen, or something similar?

I wonder, with all the strays about, how much of a cootie risk would still exist even though your kitties would be enclosed. I'm not as versed in feline disease info as I am canine, as I've never had a cat of my own. Would the airborne diseases be something you could vaccinate for, or is it just not much of an issue?

I'm worried about airborne diseases too; saw Rocket Dog and a couple of stray toms with infected, runny eyes. An enclosure within the mini-garden enclosure certainly won't help here. I'm not worried about fleas/ticks; never seen a single infested stray in the UAE yet (something that amazes me). I'm all for the enclosures, there'll be two sides strays could get close to my cats from, but we'll put a solid barrier there. Though all our cats get their vaccinations (Tri-vac) regularly, I guess there's no guarantee they won't contract an airborne disease. Wondering if there's some kind of airspray (kinda like Feliway, diffuser type, or like the aromatherapy diffusers for humans) that could minimise infection over a small area.

Or I might decide to go for a transparent, fully acrylic enclosure instead of wire on two sides. But I do want them to get fresh air!

Still undecided.

There are vaccines that prevent quite a few of the transmittable diseases, but like I noted, FeLuk is not without risk, actually, they're finding rabies shots aren't without risk either, but what does one do?
FeLuk takes blood/saliva transmission.
Herpes virus can be transmitted via sneezing droplets.

Fleas can also carry intestinal parasite eggs.

However, the risks are greatly reduced if you keep your cat out of fights.

The main reason I am considering several outdoor enclosures is to help reduce the feral population and rehab the ones I can to later adopt out or let them live out their lives in a safe place... and a sep. enclosure to give my indoor cats a way to get fresh air. The indoor cats won't be unsupervised and won't be out at night, which is when ferals generally travel.

The outdoor ferals will be much healthier out of the main population of strays, and hopefully, reduce the population.
Of course, they'll be tested for disease as I have them spayed and neutered and if diseased, euthanized.

We've generally been pretty lucky not to have much incidence of FeLuk.

Acrylic enclosure? I think you're probably safe to just do an enclosure where no cats get in/your cats don't get out.

Doubtful strays would pass fluids to your cats w/out a fight ensuing.
Once the ferals realize the food is not accessible, they'll move on.

Yes, I've seen the strays mostly in the evening or at night, never during the day. Cecil is the only one who visits during the day. Whenever we feed the strays, it's outside the compound.

I don't want strays spraying into the enclosures (can't avoid the posturing, though). Max (neutered) would go crazy if that happened, and then he'd wreak havoc, fighting with Simba and Jas-purr.

I'll probably start with an enclosure in the tiny back yard and start letting my cats out during the day, under supervision. If it works out, I'll put in another one in the front yard (that's where the strays usually prowl around, on top of the compound wall). I will not put food in the enclosures at all; during the night my cats will be kept indoors.

We've been thinking of spaying/neutering the strays, but it'll take some time for them to gain our trust enough to get close. If I had more space, I'd build a feral cat shelter too.

Jas-purr and Coco will be neutered/spayed in 10 days, we'll build the enclosures once they're back and settled in.

Pranjal