I am a bit frustrated. Four days ago, we dug in a 150 gallon Rubbermaid stock tank for a pond in our duck pen with a 2x8 ramp to get in and out. The first day, everything went fine and the ducks loved it. The second day, I went out in the morning to find three ducks floating listlessly and making unhappy duck sounds. When I pulled them out, they couldn't stand, so I warmed them up in the truck until they were happy again. I added a second 2x8 ramp, running in the opposite direction so that no duck had to go very far to get out of the water. The third morning, I found a dead duck and the other two in similar chilled condition that had to be rewarmed. I figured that there must be something wrong with my ramps, so I puled them out, drained the tank, and put in a pile of 12x12" pavers at a slight incline, right up to the edge of the tank. I watched the ducks use the pavers to easily climb in and out and figured I had the problem licked. This morning, two unhappy ducks floating in the tank again. I thought one was a goner, but she revived after three hours in the truck. It has always been the same three ducks. The one that died was never quite right physically or mentally, so I figured that was nature taking its course. The other two seem normal and healthy, other than apparently having a death wish. Am I missing something? Should I change my ramp design again? Should I just let survival of the fittest kick in?