There is a long term fall in the population of a fifth between 1995-2008.
The kestrel’s main food source is small mammals like field mice and voles and the RSPB claim that intensive farming is the cause.
According to Graham Madge
Kestrels depend on rough grassland where they can feed on beetles, voles and other small mammals. They are a widespread countryside bird so these figures are alarming. We also believe pesticides and cold winters are behind the losses which have happened in a short space of time and are gathering pace
It isn't all bad new for birds of prey as Buzzard numbers are increasing as are Hobby's. Totally unscientific I know but the Buzzard seems to be increasing in range over the past 8 years you seem more Buzzards over in the East than you did.
The survey showed a decline in small birds like stonechats, treecreepers, great tits and blue tits due to the cold winter.