Please, Please...don't use them.I have a very dear friend that discovered roof rats in the crawl space of his loft. He went to a large national chain store and was persuaded to buy glue boards to catch the rats. Catch them he did and it was horrible,...no way to catch any living creature...even if they are causing a problem.
The best way to deal with rats is to keep them out in the beginning or before they grow in number.
Walk around your loft or aviary daily for the signs of rodents or other predators. Look for tunnels and wood that has been gnawed. On the inside look for rodent droppings. The smell of rodent urine is very distinct as well so if you catch a whiff...take action.
Pick the food up every night and sweep up. Rodents are attracted to not only seed but even a pigeon dropping is a tasty treat to some rodents....the thought makes me crazy but I've seen it so I know it's true.
At the end of the day, when you sweep up, check to make sure you aren't locking rats inside with your birds.
Other than the above, I don't have any magic ideas to rid your loft of rodents. They are in our environment and attracted to birds and what we feed them. It's an on going struggle for me as well. If you do see a rat, take immediate action rather than hope the rat will go away...trust me...it won't.
Live traps work very well if you are trying to catch one or two rats. After one or two, any rats remaining become very leary and won't go near the trap for days.
Bait the trap with a piece of bread smothered with peanut butter and topped with either jam or applesauce. Once you have trapped your rat, release it to a wild place at least 5 miles away so it won't return. I always release rats in the same place, as the one before, so they can find each other. Rats live in devoted family colonies.