here in N. Ireland the main culprit is the mass killing of ivy .. Hedra helix on millions of trees ,mostly Ash .. Fraxinus exelsior . This is being encouraed by Govt. departments and the National Trust , among others , at the cost of 10's of billions of insects and 10's of thousands of tons of berries in late winter and spring .
one example is moths .. 250 of the550 species of smaller british moths are dependent on ivy during their life cycle . Overwintering bees use it as their one source of pollen and more importantly nectar in the autumn . Summer reserves went on breeding .. the winter larder is being destroyed .
Bats and birds lose food , habitat and shelter and the whole countryside (and towns ) are losing their vitality and birdsong .
Farming here is mostly grass-based , so chemicals are not a major cause of the decline.The farmers (the main ivy killers)are destroying a major ally as the ecology of ivy yields astonishing amounts of free food to the land as the trees ivy grows on are guano producing towers of plenty .
I was visited by a Department of Agriculture inspector last week who went out of her way to recommend that I kill the ivy on my trees .. I asked her to listen to the crecendo of bird song around me and pointed out how much was the result of my ivy ..