Any number of reasons I guess - the rookery was out of date, too old? They're late this Spring and will soon arrive. They chose another better place to build nests. They were disturbed by something in the area? New buildings? Trees cut down around them? Noise pollution not usually a problem. Last scenario - shot or killed but this unlikely for a whole flock.
thanks Andrew there has been building work, but trees are listed so thats less likely. i guess they are entitled to want a change of scenery. it is old at least 50 years and I'm told was the biggest in the area.
I became fascinated with the rookery across the street,
During the pandemic they would come into the garden.
They have been in the same trees for years..
I'm in a rural area..
They haven't built there nests in the trees this year .
No idea where they went.
How far would they travel ?
I wonder if there's been disturbance, or a change of ownership of the land across from you. Other possibility is their feeding areas have been developed/built on.