Kaz – It sounds as if the tree had some sort of blight to have lost most of its leaves.
Also the birds were unusual, and anything unusual in nature is usually a warning that something is not right.
So my impression is that this is about an illness that you need to watch out for.
Now obviously here am I pontificating about your dream, and maybe it is right, and maybe it is not. So be careful about thinking you are ill unless you can see signs of it.
Tony