I have finaly done it! Something that can remove and replace a block! So many exclamation marks IT SEEMS LIKE I AM YELLING!!
3 ice torches near a water block.
Place another and the water will turn into ice quickly.
There you go, when there are only 3 ice torches dodos can’t cross; when there’s 4 they can.
I haven’t tried a larger scale or if this is affected by the outside environment.
Also I found out dodos can’t walk into tiny slithers of water. Com’ on it’s only bath time!