This has been an especially prolific year for ticks in the northeastern region of the United States. We've had so many in our yard that I've given up gardening and switched to planting in pots!
We find them on ourselves frequently after filling our large number of bird feeders and bird baths. I think they're mostly in the tall grasses, wildflowers, other plants, and the regular lawn. I don't think they live in trees, though I'm not sure. Perhaps they're in the lower sections, near the grasses and vines.
There are very few deer in this neighborhood, but I know dogs and other animals, like the fox that's been wandering through every once in a while, leave ticks here for our enjoyment!
It only recently occurred to me that birds might be affected. We can clean up most of the obvious places where the ticks hide in our yard, but that doesn't mean the birds are safe. Obviously we can't clean up the woods or water sources inhabited by the wild birds.
I don't recall hearing that birds are affected by ticks, but I've never studied it either. Do ticks like birds, whether in the yard or in the wild? If so, do they bite them as they do with humans, or do they hang on and use the birds as carriers?