I had to place a thin board over top of my heated buckets to keep the ducks from using them as a hot tub. you can kind of see here but it does keep them from climbing in. Plus with your temps I'd be worried my ducks would freeze climbing into buckets. :welcome
Wow we have blk bears we actually live below a bear sancutary [Mt Mitchell] and thankfully never had one try and get into our coops. They have made off with wild bird feeders [until I finally got smart enough to bring them inside at night] and even got into our trash can but thankfully never...