Well, almost walking on water. Fall means there are some water plants that take over the surface of swamps and ponds. I have been told it may be some type of water chestnut. Sounds good to me.
These are tall birds, but weight hardly anything. Their big (enormous) feet grip everything.
The water is shallow so a slip means little.
I’m not sure how they see prey but they slowly work away and seem to catch plenty of small ‘slippery things’.