Common Merganser - Preening

As Yogi Berra said, "You can see a lot by looking...". Often I see even more by taking a photo, as when in the field our eyes are drawn to the most obvious/attractive features of the subject and we may overlook or ignore some interesting subtleties.

On a recent trip to the Las Gallinas Ponds 4 adult male Common Mergansers vied for resting space on the guano-covered pipe, and one of them provided an entertaining display by actively preening. I counted 18 rectricies (tail feathers).

I was mesmerized by the feather display, with wings half spread and tail fully fanned. Viewing the photos later I saw how the uppertail coverts were partly erected. Most of my photos showed even more of what was hidden underneath at the base of the tail, as shown below. Also check out the toothy grin.

Whoa! Not sure I liked what the photos revealed, until it suddenly clicked that when birds preen they often reach back to rub their bill on the preen (uropygial) gland at the base of the tail, collecting oily/waxy secretions that can be spread on the feathers while preening, perhaps to reduce wear and provide water-proofing. This  can be best accomplished if the feathers overlying the gland are lifted up.

You may not enjoy a closer view, so you can skip this last shot, cropped from the above.

Geez, only took me 20 years of watching birds to finally see this important feature!