I have a 16-300, and few of my wildlife shots from it are as nice as that! I was able to view the pictures on a different computer finally.
One thing I did notice in the Tufted Titmouse picture was the green fringing on some of the branches. It is chromatic aberration, and is pretty easy to fix with Lightroom’s built-in lens profiles. Good job getting down to the rabbit’s eye level! That blade of grass sticking up in front of its nose- I found a fawn once, and got some really nice pictures of it, only to find that a troublesome weed was growing in front of it. I was able to brush it out, but it would have been nicer if I had framed it better to avoid the edit.