The Herons have gone?!

Hi,

I have been having two Herons visit over 3 years now,with one coming every day for the last 6 months and one,just once per week.Over the last 3-4 days there has been no sight of them anywhere which I find so very odd. The smaller one of the two which came probably 3-4 times per day seemed quite at home.Do they just disappear and find new pastures?

It just does not seem the same with them not popping in!