I wouldn't worry about the cat's comfort UNLESS it's really cold out. If it's freezing, don't spray it with a hose. If it's not freezing, spray it all you want. It'll survive.
You don't have to stand there and watch the trap. You'll probably hear it close, and just keep an eye on it every hour or so.
I have been thinking more about this and I like the sprinkler suggestion. You can get a sprinkler with a motion sensor. You can also get some motion-control lights. Anyway, as I see it you options are as follows:
- Live-trap the cat. This alone might be enough because cats hate being trapped. Otherwise, you can bring the cat to its owner saying "your cat came after my rabbits so I trapped him, please keep him indoors, if I trap him again I will have to bring him to the shelter." Or go straight to bringing him to the shelter but know that if he is not young and friendly he may be euthanized which would be sad.
*IMO this is a band-aid solution because it only deals with this one cat. I guarantee you there are more predators around that you haven't seen yet (especially with winter coming).
- Observe the cat. Is he actually hunting your rabbits? It wouldn't surprise me if he was but he might just be hanging out. At home I have an angora rabbit, two small parrots and six cats. The only ones who get attacked are the cats, by the birds
That said, I had a hungry stray cat attack my rooster. The cat came away much more banged up than the rooster.
*Again this is just a bandaid
- Speak to the neighbour. Honestly, some people are just clueless. He/she might be mortified to find out what his cat has been up to.
*Again, only deals with this one animal
- Finish your hutch ASAP. Large rabbits in a fenced area in the suburbs are relatively safe during the day. If you can put them in a safe place during dawn, dusk and night, it should be fine.
*This one doesn't address daytime predators but I don't think that is too likely.
- Use deterrents - motion activated lights and sprinkles, spraying the perimeter (outside the fence) with a cayenne-based repellant (google cayenne raccoon repellent for more ideas).
*Repellant needs to be re-applied every few days but it REALLY works. I had racoons or foxes or something trying to dig under my chicken run. It's fort knox but I still didn't want them trying so I put repellant all around every 2 days for a week and they stopped coming. It hurts like hell but it's not permanently damaging. And it doesn't bother birds.
*This is probably your best, cheapest option combined with getting the hutch up ASAP.
- Get a dog. This is kind of a far-fetched idea but if you were thinking about getting a dog, you could get a livestock dog that will protect your rabbits. But then you have to feed the dog, train the dog, vet the dog and walk the dog.
- I know I keep harping on about the run but... this is your #1, first class option that will protect your rabbits from ALL predators, day and night. You can still let them out of the run when you're home during the day. Use 1/2" solid steel mesh so nothing can reach or tear through it.
I would NOT suggest:
- Feeding the cat. If you suspect the cat is stray or feral and is hungry, the kindest thing to do would be to trap it and bring it to a shelter. Feeding it so it won't eat your rabbits will work for a day but you may end up with a cat colony in your back yard. If it's just a local indoor/outdoor cat that likes to hang around, it probably wouldn't hurt to feed it a bit, but I don't think it'll really accomplish anything.
- Standing on your deck and spraying. Mostly because that's a waste of your time and is not a viable long-term solution.
- Trap and relocate the cat. If you take the cat far enough that it won't come back, it will probably starve or get hit by a car wandering around. If it's an owned cat you would be taking away someone's pet (granted, someone irresponsible, but some people just don't know better). If it comes to that, bring it to a shelter.
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Unfortunately any way to eliminate the problem without you standing around all night is going to cost you money and/or require you to do some work, unless you can find the owner of the cat and he agrees to keep the cat indoors. With predators, there is no magic answer, and you have to do what you think is necessary to protect your pets from predators... preferably before you lose a rabbit.
Good luck... keep us posted!
Edited to ad: Just to give you an idea of how pervasive and persistent predators are... there are coyotes in Manhattan and in Queens.