So I'm new. Ok. I admit it. Haven't had much training trapping ferals and am sort of flying by the seat of my pants. I learned an important lesson this week; don't leave the trap outside unattended.
I haven't had any problems leaving it in barns, sheds or garages overnight, but do NOT leave it outside in plain view and open to the elements. There are a few reasons for this.
1. If it rains the cat doesn't have any shelter and it will get wet ... that sucks and is not fair for the cat. Do you know how ornery a wet cat is? A cat will go from a 3 on the scale to a 9 in 5 seconds flat.
2. Sometimes you will catch something OTHER than a cat ... that sucks even more than a wet cat. Then you have to figure out what to do about it! (please refer to my earlier entry about trapping the striped ones)
3. If the cat is super feral and it is strong enough to roll the cage itself, you may have a long search to find the trap ... a great waste of time. (Try at the bottom of the hill first.)
4. If some human comes along and finds the trap with a cat in it, you may find it missing the next day. (Call canine control - they may have received a call about this) This is where you will start panicking.
5. If a human finds the trap and you're lucky, the cat was released unharmed and the trap taken. Usually this results in a call to the humane society (or equivalent organization you're TNRing for) where you get to explain to them how this happened. This also sucks and may result in people looking down their nose at you; never a good thing.
6. If you're not lucky and a human finds the trap, the cat may be subject to any number of terrible things including kicking, rolling of the trap; drowning the cat; shooting the cat; etc. This is worst case scenario - I have been told about it but have never witnessed it myself.
In short - don't leave the trap outside unattended. There are too many possibilities and consequences.