Posted: 30/06/2015 at 14:44
If it's being eaten it won't all be eaten and will come back next year or maybe later this year. Native trees have native wildlife that eat bits of them, it's all part of the biodiversity. It doesn't kill them.
Hard to tell from the photo but doesn't look like a rowan.
If you think too many leaves are yellowing and dying off have a look at the trunk. Has the bark been damaged?