My job is my excuse for my light collection..
If you have seen droppings than it is mice, what type of insulation do you have, often it is pink batts layed down, if this is the case you will be able to go directly to the area you hear the noise, peel it back and see the discoloration on the plastic barrier, as well as droppings. Often the noises are most prevelant near the nest, often near a source of heat, pot light, ceiling fan.. Or you may have a blown in style of insulation, as soon as you open the attic you will see signs of the intruders, they burrow through the stuff, it ends up looking like a gerbil cage, paths and burrows everywhere.
Glue traps will not fix the problem.
Rat droppings are far bigger, and hardly ever found, they tend to have "areas" they use for that purpose, like a cat would. Chipmunks can get into attics, but it's not as common, they tend to scale the inside of downspouts and chew through attic vents, very difficult to locate the holes. But thats not what you have.
Mice often scale the wall and enter in the tiny gap between the brick and the soffat, most often it is not nessasary to try to seal that, it is also very difficult and time consuming.
Can you get me a pic of the outside of the house? One of the dropping would be good too, if it is still where you found it.. PM me for my email addy.
9 times out of 10 mice scale the wall and live in the attic, almost everyone has them there, once they create their home they often begin to decend (or fall) down the walls, sometimes that is heard, other times it's not. From the wall they get into the basement ceiling, their quest for heat (not food) leads them to hot water lines and then quickly up under the kitchen sink, next stage is mice in the kitchen. It is not impossible that they will contain themselves to the attic though.
Try not to spend too much time in the attic, one reason is it is very unhealthy, the other is because if you choose to evict these little guys your smell may deter them, they are a very scent orientated rodent, and spending too much time up there could cause them to change their routine, and slowing the removal process.
They have to be killed, glue traps teach them to avoid glue traps, electronic deterrents have 0 affect too. It is a great time of the year to take on a tiny project like this, the weather is on your side.
Again pictures would be great..
A picture will tell me the age of the house, insulation type as well as the entry point.. We could have it over with by the weekend..