Strictly speaking, bats and birds don’t carry bed bugs. They carry related types of insect parasites with blood sucking behaviors similar to those of bed bugs.

If you have bats in the attic, they may be bringing bat bugs into the house, which are then crawling in the inhabited areas and biting you. Similarly, birds can bring chimney swift bugs and swallow bugs into the house. It takes a professional to tell the difference between these bugs and a bed bug, and the methods of treating them are different. Nonetheless, if you have any critters in the house, you have to get them out and seal up their entry points.