Sealing up all the entry points can help, but there are things you can do as well.
For example, many people get rats or rodents because they don’t do a good job of keeping outdoor garbage bins secured. This attracts them in the first place. Then they target the attic, where insulation and a lack of human traffic provides them with a warm, dry nesting environment.
If you feed birds then you need to use a feeder basket and reduce the amount of food you’re using. Try to put in just enough to feed the birds during the day, ensuring nothing at all is left behind at night.