Sparrow infestation in leylandii hedge
We have a serious problem of sparrow infestation on the cypress leylandii hedge. We have about 40 trees formed as a tall hedge and in the late afternoon hundreds of sparrows come in the trees to sleep for the evening. It is gaining on for several months now and the numbers seem to grow. We noticed the inside brunches of the leylandii trees are starting to turn brown and die, I suppose from the birds' excrements which are too strong. Maybe this contributes to some fungi infestation as well. On the outside the trees look very good still, but it may not last long. We tried artificial owl and hawk scarecrows, as well as putting shimmering tapes, but as the sparrows are inside the trees those didn't help much. We have several dogs that go and bark on the trees but the sparrows do not notice either. I would appreciate any suggestions, my husband put a lot of effort in this hedge.