Otters like to potter along the river bank, and their spraints can be seen, usually in specific locations.  Advertising their presence both as a territory marker, but also as a social/mating statement.  On the opposite bank, hidden in trees is a pond in which toads live.  Every spring, they migrate to our side of the river, and provide food for the otters.  They zip them open down the front and extract the vital organs.  Not much more on a toad really, so the otters abandon the carcases.

If you look closely you can see the carcases in the rock pools.