They made a bit of an odd couple, but this scaup and this Pied-billed Grebe (Podilymbus podiceps) seemed happy together as they paddled around in the waters off of Occoquan Bay National Wildlife Refuge on Monday. I have the distinct impression that birds are increasingly willing to tolerate the presence of other species during the winter months and it is not uncommon for me to spot mixed flocks of birds in the water and on the land.
The Pied-billed Grebe has a very distinctive look and is easy to identify. When it comes to the scaup, however, identification is a bit more problematic, because there are Greater Scaups (Aythya marila) and Lesser Scaups (Aythya affinis). Lesser Scaups are somewhat smaller than Greater Scaups and their heads are shaped differently (the Lesser has a thinner, more peaked head than the Greater Scaup, which has a more round head), but I have never been able to tell the two species apart.
I really like the visual comparison in the photo between the size and shape of the bodies and bills of these two swimming birds as well as their very different coloration. Birds that look different from each other can live together in peace. Why is it that we humans can’t do the same?
© Michael Q. Powell. All rights reserved.
Mike Powell 
Lovely pair. Grebes are beautiful and this image is interesting with its differences in size, shape and coloration.
Thanks, Chris. We have several types of grebes in my area, but the Pied-billed Grebes, like the one in the photo, are the ones that I see most often.
The first thing that came to mind when I saw your photo was commensal feeding: the tendency of one species to feed in association with another. I see it with white ibis and snowy or great egrets. I wondered if grebes engage in the practice, and the answer seems to be ‘yes.’ I found a journal article that says, “The literature review revealed that commensal feeding Little Grebes had shorter diving times, shorter recovery times between dives, and higher feeding rates than non-associated congeners.”
There are more details in the article, which you can find here. I saw other articles listed for other grebe species; it’s all very interesting.
That is absolutely fascinating. I checked out the article and was intrigued to see that the grebes, which dive, were with mallards, which dabble. I wonder if it makes a difference when they both are diving birds, like the ones in my photo. All in all, it boggles my mind to think about the whole idea of commensal feeding.
Great photo Mike. It’s always fun to see odd-matched birds hanging out together. I like this photo because you captured their movement, too.
Thanks, Jet. Each of the two birds would dive periodically and then would swim back together. I was happy to be able to capture an image when they were both turned in the same direction. It is always fun to watch bird behavior–I never know what I may see. 🙂
Great photo, Mike. We humans could learn a lot from animals.