Went to check the rafts at Prees Branch Canal again, and almost immediately found a dead water vole on the path. It didn't seem marked in any way, which to me suggested a cat had killed it, and when I mentioned it to the lady who lives in the end cottage, she said she'd seen one hanging about. So many things will take a water vole - herons, swans, rats, all mustelids (weasels, stoats, mink, polecats, otters, pine martens), many birds of prey, pike and foxes - so it's depressing to have to add cats into the mix as well. At least when an owl takes a vole, it's to feed itself. I'd ask all cat owners to fit their pets' collars with a bell, and to keep them in between dusk and dawn (cats are safer kept in at night anyway, as this is the time of day a lot get run over).
Anyway, I was able to get close-up photos of the hind feet, tail and teeth, and to measure it; this water vole was 11cm from nose to rump. The orange teeth are a characteristic of adult water voles, and can be seen on my earlier post about the skull. Water voles' teeth are used for digging, so they do have to be very large.
Still quite a lot of feeding going on down the canal length, including again some nibbled snails (see fourth photo down), and when I checked the lower raft, there were fresh water vole droppings on the wood section and on the clay.
I include the top picture to show good landowner practice: this farmer has allowed a protected margin of vegetation along the side of the canal, and built a cattle drinker so his bullocks can come down to the water without trampling the banks into a muddy mess. I've done survey work round this farm ( http://staggsbrook.blogspot.com/2007/06/whixall-hall-farm.html ) and the owner is very keen on nature. Three cheers for people like this!