On the bank of the river between the two bridges there is a small patch with no overhanging trees which has its own selection of flora. I think this is fumaria. The flowers are only around 1 centimetre long (0.4 inch).
"Will they ever learn?".... obviously not, it's their home, they are use to it, stands to reason they will always want to go back there ~ damn shame that something can't be done to help ~ if they were an endangered species they would get help from all quarters, I'm sure of that!