do bluebirds in northeast in. migrate in winter?

Answer 1

Most of them do. They go as far south as needed for adequate food sources. During mild winters, a few may stay year round, but most end up from southern Virginia to Central America. I remember seeing all 3 species of North American bluebirds appear in Guatemala at the end of the year while I was living there, and then 2 species migrated back out in the early spring. When I ran a nesting box trail in Pennsylvania, we would see occasional birds stay through the season, but usually they would leave. Our banding program proved, incidentally, that the same birds would return to the same nesting site each year if given the opportunity.

Answer 2

Cardinals are a non-migratory species, they have evolved to be able to find food in the winter so they don't have to leave. My advice is stop worrying, and maybe put up a feeder so you can watch them better without them bugging your cats.