This past Saturday after my encounter with a cinnamon-colored squirrel (a variant of the Common Gray variety) in Central Park, I came upon a Mallard duck preening and he can be seen in the first image atop this entry.
I am fascinating with the preening process, which I've witnessed many birds doing, including a mourning dove when he/she alighted upon the branches of an Ailanthus tree in my courtyard (as evidenced in the second photo above).
Details re mourning doves and their preening process are included in volume one of my book series, Words In Our Beak. And information about Ailanthus trees is included in volume three.
Here's the purchase info for each book in my series:
Volume One: ISBN: 9780996378529
Book Seller Info: http://bit.ly/2q75g8e