my backyard is facing a lake with a lot of ducks. I rescued 3 ducklings, they are 3 weeks old. can I let them free in the backyard? I have been keeping them inside the house at night and during the day, in a playpen area (fence with door) with sun shades, so they can't get out to go to the water, I place 2 wading pools in the playpen. I want to let them free but not sure if this is right thing to do. If they get to the water, how long they can swim? i build a ramp for them, not sure if they will use it. Any suggestion?