Herons will travel far more than seven miles. Heronaries consist of up to 100 nests. The latest RSPB figures show 13,000 mating couples in the United Kingdom. They divide into 'flying zones' and will set off at dawn on a circular flight path. If they find rich pickings in one location - say eels in the Witham then they will sit patiently for hours. They can go days and days without food. But if push comes to shove then they will at dawn go after baby
Rabbits on river banks.
Also it pays to know that if your fish stock in your ponds deplete, it may not be the heron who is the guilty party. Mallards eat goldfish, so it pays to have a deep pond. Ours is nearly six feet deep!