I think hares can evolve in a few generations, we used to run the fens twice or sometimes three times a week. Some places, every man and his dog knew about, Sunday mornings were like the Waterloo cup ! Now these hares were very hard to catch, only the best survived to pass on their genes to the next generation. From time to time we would stumble on places that others knew nothing about, this was obvious by the fact that the dogs would wipe the floor with the hares, simply because the weaker ones had not been weeded out, they lived to pass on their inferior genes. As a side note, the best hares