If the sounds you are hearing are baby birds along with adults, you might want to let them finish growing up before taking any action. It's been my experience (although I'm not a bird expert) that after the babies learn to fly, the entire bird family will abandon the nest. Then, you could try covering the vent with hardware cloth (metal mesh) so that other birds don't try to nest there again.
Once the nest is established, the majority of any "damage" is done; your vent is probably full of twigs, straw, etc., but the nest is probably not doing any additional harm to your home.
We had a bird family living under our eaves one year. Had a great view from the window of their comings & goings. It was like having temporary pets. :)
Once they flew away, we removed the nest & discovered that they hadn't really done any damage. These were small birds, sparrows, so if you indeed have turkeys nesting in your vent or other large birds, you may want to disregard my advice... :)