Hi Richard,
Oh I know that there are rats about - bound to be but it was the sheer number we were seeing that was the problem 2 years ago and why we had to deal with this years sighting quick smart.
I will never quite forget the utter disbelief my OH and I felt the
first time we wondered out into the garden during summer 2010 and counted
7 of them sitting in the veg patch just looking at us

They didn't even run when we came towards them!!!! That was not good and it happened on an almost daily basis.
On several occassions we caught 2 juveniles at a time in the trap and when an adult female was eventually poisoned (nuclear strength stuff put down at the school by the pest control people when the colony spread that way) she was 25 inches from snout to tip of her tail!!!!
The problem was only solved when the houses at the back of us, who had a grandstand view into the back garden of the neighbour with chickens, contacted environmental health and asked them to investigate the garden as they were convinced it was the source of the problem.
A huge warren was found under the garden with dozens of entrances, so I was told by one of the families involved and the chicken keeper was told to tidy up, get rid of some of his birds (he had in excess of 40) and to put bait down at each entrance, repeatedly, until it was no longer nibbled!!!
The money we had all been spending on rat poison had been wasted because the rats were eating vit k rich chicken pellets which was then counteracting the effects of the bait which they were also eating!
Incidently we've sited our composters on concrete to prevent unwelcome squatters and introduced worms etc from spent compost used in tubs and pots.
VPM
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