Please help me catch this cat

Hi,
I am a current owner of 2 tiger tabby cats I adopted when they were 7 months old back in August of 2001. Recently I bought a house in my neighborhood I live in. Since the aquisition of the house the cobuyer as started a bunch of remodeling and has removed all the registers over the vents. About a month ago my fiance' brought home two siamese cats that were only supposed to be with us for the weekend. They were supposed to be given to his aunt who backed out on the deal. By the time she backed out one of the siamese became missing. We couldn't find it anywhere. I didn't know if it got out of the house or where it could be hiding. About 2 weeks later I started smelling cat urine and such coming from the vents of the house. but as i pounded and made noise in the vents I did not hear anything move. My fear was the cat got trapped and died because I never heard any noises or anything from the vents. That was until yesterday morning. About 6AM I woke up to the distinct siamese meow/whine. As I lifted my head up I saw both siamese on the floor in the front of my bed. As I tried to move to grab the one he dissappeared under my bed but when I looked under the bed, it was gone. The only possible escape route was from the vent behind the bed. I set up a pet carrier with some food and set it up in the bathroom leaving the bedroom door to the bathroom open. About 10 mins later the cat came back out and wen into the carrier to which I was able to trap it. I had it locked up for several hours but stupid me tried to interact with it so I took it out of the carrier and was trying to so affection and interact but it wanted nothing to do with us and continuosly tried to get away. I tried to put it by food and water and it would dart to the top of the stairs where I had it blocked off. Finally after one last time it darted and hopped over the blockade and got loose in the house and I fear it went right back in the vent again. The next night I woke up about 4AM and encountered it in the stairway to which it quickly darted and I heard it go back in another vent.
What can I do to flush this cat out of the vent again to catch it. One I have it I am going to surrender it to the SPCA since I cannot get it to interact with humans.

I don't think you should say you cannot get it to interact with humans. Don't take it to a shelter yet. If he is this nervous with you he will do nothing but go downhill quickley sitting in a cold steel cage day after day. I urge you to please not do this. He is just scared and needs some time to adjust. Has the cat not eaten in this 2 week time it was in the vent?

You need to trap this cat again. Either the way you did or else borrow or buy a humane trap from a feed store or the vet. Trap him and put him into a room with no vent access. Like the bathroom. Then go around your house and block the vent entrances. Once you do that you can let the cat out of the bathroom. But until you do feed him and give him a litterbox in the bathroom (or laundry room or bedroom with no vent).

All you need to do is get the cat on a set schedule so he can rely on and trust you. Don't attempt to interact with the cat. Just provide food and water at set times everyday. Read to him sing to him talk to him but don't stare at him or apporach him. He will come to you eventually. This cat is probably terrified from being on his own so long.

Is he agressive towards you or just not wanting to be held or pet? If he is agressive then this process may take a little longer, if he is just shy it won't take so long. You cannot expect him to immediately love and trust you. He was taken from wherever he was previously, brought to a new strange place, lost in the vents for 2 weeks, trapped, released again...he is scared, calm down and give him time. That is all he needs.

Please do not take him to the SPCA, it will not be a good thing at all for a cat like this, believe me. I worked at a shelter for almost 2 years, these type of cats stop eating and very quickly lose weight and just give up and die. Please please don't let that happen to him. If anything put an ad out that he needs a new calm quiet caring home. I would not split him apart from the other cat if they are close or related at all, in fact, keep them both together in the small room I mentioned earlier and use the other to help calm this one. Are they both neutered as well? That will help with many problems too.

He didn't hiss or swipe or try to scratch when I did get him the last time (but his tail poofed out big time), but he was looking for anyway possible to get away and hide again. In fact when I was petting him and rubbing his chin he was purring amd started to play bite, but you could tell he was also very very cautious. This was even from the first time he was brought in. He just ran and hide and if you tried to approach him he's avoid you like the plague and run somewhere else and hide.

As far as eating I do not know if he ate or not but I did notice that food was dissappearing quicker the usual. I have three food bowls in the basement with a water bowl, and a small water dish and food bowl in the bedroom and each morning all of them would seem to be almost bone dry.

apparently from his last place both cats were abused and picked on by other animals not by the owners. So I feel they might be terrified of my long owned two cats whom are the sweetest things ever.

I would like to be able to put both cats in a home together but the one siamese that has opened up to us a bit more my fiance has become attached to her. The one that has warmed up will come up to us and interact but if you approach it it will shy away but not dart like it fleeing for it's life like the one thats hiding.

As far as neutering I was informed they were, as my two cats are, but there are not Tatoo's in the ears as if it was done by a shelter. I just got to get him out of the vent so I can have them professionaly cleaned and all the vents closed off with the registers installed.

I would give it time if you would like to keep them. I would suggest following some of the things I mentioned and just give them about a month and see how things are before giving them away. Actually, if your cat accepts this one, then your cat may actually help this shy one come around.

If they are not neutered you can tell just by looking at their rear end. If you just run your hand quickley between their back legs under their tail, if they aren't neutered you will clearly feel a distinct hardness back there which would be their, um, balls If you don't feel or see anything with a quick look then they are neutered. They will probably not be tattooed, I think only ferals are.

Seriously just give them a month. I can almost guarentee things will be noticably different in that time if you are patient and follow the advice on these forums. It is late and more people will be around in tomorrow to fill this thread up with suggestions. To introduce them to your resident cats, check out the sticky's on one of the forums for introducing new cats.

I forgot to mention. What you said in your first paragraph there, that he play bit, purred, etc. That is great. I bet you he wants the attention and love but he is just being cautious like you said. Not hissing or growling is great. Tail poofing is fine, he is scared. Just care for him but don't push him. This will work. You will have a great little cat in no time.

Try some warm wet tuna in a carrier and see if you can't get him that way. I keep forgetting he is still in the vents. If not then call a vet or shelter nearby and ask if you can rent a humane trap. If not they are about $50 to buy.

You might want to also pick up some Feliway Plug ins to put around your house. They are great for helping moody cats and to stop unwanted behavior (good for introduction to your housecats)