I have a system that attracts birds and satisfies their feeding and bathing habits, and waters my trees at the same time.
My front yard is mostly pine trees, with wells dug out around the base of the trees. I scatter bird seed everywhere early in the morning, and turn on the bubblers that fill the little wells around the trees. The water attracts the birds, they splash around in the wells, and then discover the bird seed.
It's California though, so the trees only get watered twice a week at most.
I sprinkle bird seed every day though, and some of the birds remember to come back every day for meals. Watering days really attract a lot of them, though.