There are two main species of rats in the us the roof rat and the norway rat.
Common attic critters.
The roof rat is more common in warm areas and more likely to enter the attic.
Insects such as cockroaches spiders mosquitoes and termites.
The most common critter to enter attics in many areas including where i work in florida is the rat.
This is a good place to start because most of the time that sound is going to be one of these two critters.
Tips for removing animals commonly found in your attic.
Cockroaches will only invade your attic if you leave food in that area behind.
Common animal entry points.
Common pests possums and squirrels are rather common in florida attics and can usually be noted by droppings if you have the courage to venture up into the attic to figure out what that sound is.
But if one or two of them find their way to the attic expect an entire family or even a generation of cockroaches taking over the space.
Roof rats aka black rats often build nests in attics.
Rats and mice in the attic.
Squirrels are diurnal they re active during the day.
Raccoons are similar in habit and often do a fair bit more damage to insulation.
Most often if you have squirrels in your ceiling it s a mother who needs a safe place to give birth and raise her babies.
Because they need water daily they tend to nest where water is readily.
They chew their way in and then keep chewing once they get in making a lot of damage along the way.