No water voles?

Up in Shropshire, Kate seems to be seeing a water vole boom - where the voles have become so brave she is even feeding them by hand (as well as getting some great photographs):

http://staggsbrook.blogspot.co.uk/2013/08/when-voles-grow-bold.html

However, along the Ock, it is a more solemn story, where last year there were water voles feeding on the arrow heads, this year they remain untouched:
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This has lack of grazing has allowed some of the river plants to flower, including this flowering rush:
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When there is an obvious decline in a water vole population the first suspect is the presence of american mink.
However, there are several young moorhen of different ages (more than last year), which are often a favourite of mink:
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So maybe the reason is more complex - perhaps this years wet winter followed by a very wet spring combined with a natural low breeding cycle has resulted in a lower population.
However, along the Lower Ock, there are signs of water vole activity, a latrine:
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As there is over 20 miles of water vole habitat along the Ock and its tributaries and as water voles are fast breeders it is very likely that the water vole population will once again increase in subsequent years.
That is of course assuming that reason for the decline is not the presence of mink....