Posting a question on behalf of my mom (who leaves nearby). Her oak tree has been dropping clumps of leaves off the end of the branches. You can see the dead clumps scattered through the tree and all over the ground. She said she picked up about 30 clumps after returning from vacation recently. They are mostly broken cleanly from the end of the branch. Maybe squirrels? But why would they do that? She has never noticed this, at least not to this extent, before, and has lived in the same house for over 15 years. No gypsy moth, and tree is otherwise healthy. She has seen it in some other oaks in the area too. Any ideas? See photos below. Thanks!