Yes because that is very sad when you have to scoop a barn kitten out of it. I have ropes tied to my fence and they dangle in each of my tanks.Whatever you use, I recommend putting a hardware cloth (heavy screen) ramp on it. You can bend it to hang on any edge. It will save the sadness of finding drowned animals or birds in there.
I've worked on outfits that had galvanized and/or rubber tubs. Where I lease now, the owner is brilliant with tire tubs that have constant exchange of water from the many creeks.