Juvenile Pied-billed Grebes, Fernhill Wetlands, Forest Grove, Oregon on 19 August 2010 by Greg Gillson.
Last month I photographed the sinking dives of a Pied-billed Grebe at Fernhill Wetlands, in Forest Grove, Oregon. This week I photographed two birds there, one of which is probably the same individual.
These two birds have been hanging around the ponds there. From a distance I noted that they were regularly holding out their wings. So I walked closer to investigate, obtaining the photo above.
I observed that the grebe (the bird farthest back) holds its wings out about 3 seconds, fluffs its back feathers and shakes its back and tail, as in the next photo below, taken 6 seconds after the top photo. [Click photo for larger view.]
This behavior is called "feather settling." It is one of a number of maintenance behaviors that presumably gives the bird comfort. Other comfort movements are yawning, stretching, and resting. Many behaviors in birds are innate--they are instinctively performed following a constant pattern. Feather settling is often performed by raising the feathers, shaking the body, flapping the wings, and finally depressing the feathers down into proper position.
This reshuffling of the feathers was performed several times alternately by both birds. In the photo below the other bird takes its turn (6 more seconds after the second photo above). [Click photo for larger view.]
I realized that I had seen this before, without really thinking about it. Rich Ditch recently photographed a Pied-billed Grebe with its wings out. Now I know what it was doing!
This also explains the bizarre "fuzzy gull" I photographed last week at the coast. The adult California Gull fluffed itself all up as you can see in the photo below. [Click photo for larger view.]
Then it shook itself and flapped its wings. [Click photo for larger view.]
This gull was very worn. The feathers of the tail has lost most of the vanes and the tips are just bare feather shafts. This bird needs to start its fall molt and replace its old feathers very soon!
Perhaps this gull is getting new feathers and they itch? That would explain a reason for feather settling, too. As a matter of fact, the juvenile Pied-billed Grebes are also going through body molt. Itchiness might explain the repeated feather settling they are doing.