There are some trees that I always look at if I’m near them. I have my patch, the raptors have theirs. Standard small falcon silhouette above. I’ve never seen a Merlin on this tree, so I had to get closer to double-check. American Kestrel male, a regular up there.
Here he is again. On another perch this time, a linden. And not just any linden.
Not just the same tree, but the same spot. This is a favored tree of Merlins (it’s been at least two years now, is it more than one Merlin?).
The Merlin took off as this Red-tailed Hawk came into the tree. Earlier this month, the Merlin flew off as a Coopers landed in the tree.
Some more of this Merlin. Stropping bill on the branch right above.
Backyard and Beyond 
There is now evidence that some of the “stropping” is more about leaving scent than honing a bill. A book, The Secret Perfume of Birds by Whittaker is my source.