Attila, he had these mice stored in the nest, we first spotted him in another tree then he flew to the tree with the nest, we could see his head movements to that of tearing at something, when we moved a little closer looking through the lense we could see he a mouse, it wasn`t untill I looked at the pics on the computer that I realized there were two mice, who knows maybe more. The mouse in his mouth is light coloured and I think light grey on top, so I would say are wild mice and the kestrel was storing up his bounty. I thought this to be interesting behaviour, nature at it`s best.
Steve