It’s said that you will love your Sigma 50-500mm lens as long as you don’t point it up a tree. Here is proof. I shot about 20 photos of this Changable Hawk Eagle perched on an Alastonia tree but only one came well. Even then there is room for improvement.
There are certain light conditions though which allow the lens to be pointed up at a tree, a clear sky with the sun behind your shoulder is one of them.