We once had about 20 gerbils escape at once when I was kid- and we found them all. Actually, over the years there've been multiple small animal escapes and all have been found, although some met up with the dog before we found them
Some advice- they tend to be more active at night, and when its quiet. We could spend all day tearing apart a room and not see it, but if you wait until evening, turn out the lights, and sit and watch, you're more likely to spot them.
You can make your own trap with some food, a bucket, and some sort of ramp. Place the food in the bucket, make the ramp lead up to the lip of the bucket. Gerbil has to go into the bucket to get the food, and will not be able to get back out (theoretically) no, I've never caught anything in such a trap, but they're recommended everywhere, so I assume someone, somewhere has.
If you have a good idea where the gerbil is try to seal off that room. It will be easier to catch him if he is confined to a smaller space, like the bedroom, than if he can go running around the whole house.
If you use a commercial trap, be careful what you choose- gerbils are bigger than most mice, and smaller than rats. Plus, I think most are smart enough to avoid traps. In any case, make sure you use a live trap.
It might help to put his cage on the floor, if its safe. His cage will be familiar and he is likely to return to it. Even if he cant get back in, if it attracts him, he'll be easier to spot. If you cant do that, try putting a similar cage on the floor, with food, water, bedding, and leave the door open. I have had this work, he may come home all on his own and stay, put keep an eye on it because he is likely to be attracted to it.
If you do spot him, remember do NOT grab him by his tail! Gerbil tails deglove and fall off VERY easily. I've seen numerous gerbils missing tails because someone tried to grab them this way. In the wild this is useful, because their tail detaches and a predator is left with a tail but no gerbil. At home, not so much.
you might get a large, clear rubbermaid container. If he is not very tame, or you worry you cant catch him without grabbing, pop the container upside down over him- he wont be able to get out until you can find a safe way to extract him.
As far as damage- gerbils are prolific chewers. Of all the small pets, they chew the most, by a long shot. They can go through a block of wood in a night if they want. I'd imagine if they found an expensive block of wood in your house, yes, they could do quite a bit of damage. And of course, there is always the danger he'll get into your walls, where he could chew insulation, wiring etc.
I hope you find him soon. I'm sure he'll show up!
. I hope you find the little dude before bedtime.
