Sunday, January 27, 2013

Oatka Creek Park • January 26


Pileated Woodpecker. Today's hike in Oatka was taken during the midday due to the cold single digit temperatures of the morning. The Pileated Woodpeckers were still out and about, briefly calling to each other from different parts of the woods and hammering away at the trees. Though alert to my presence as I made my way through the trees, this female tolerated my approach and never left her perch. She clearly was more interested in excavating the tree.

Pileated Woodpecker. These birds have an interesting investigation technique that I have not noticed with other woodpeckers: first they hammer for a bit, then they turn their heads fully ninety degrees as if to put their cheek on their shoulder. They first turn to one shoulder, and then the other. They appear to be triangulating on the area in the tree they are evacuating.

American Black Duck amid Mallards. Being cold, the shallower ponds of water in the area are frozen over. At these times the raft of Mallards on Oatka Creek grows noticeably. (The current of the creek is strong enough to prevent freezing.) Once you have a dozen or more Mallards, it seems the American Black Ducks and its hybrids will show up, too. This duck looked like a "mostly pure" male American Black Duck. (Due to its frequent hybridization, truly pure American Black Ducks might be hard to find, but see below.) There was an obvious American Black Duck x Mallard hybrid out of shot to the left that wasn't being cooperative photographically.

American Black Duck amid Mallards. Though the American Black Duck is looking away in the background, it is easy to see the differences with the female Mallard in the foreground: the biggest and best difference is the color of the bill - dark yellow for the Black Duck and orange with black for the Mallard. I have heard a lot of talk about American Black Ducks breeding so much with Mallards and other similar duck species that they might "disappear" from the genetic landscape. Cornell's Birds of North America, however, seems to say that is not likely: "Hybridization of an abundant species with a less abundant and declining one can lead to genetic extinction of the species with the smaller population. American Black Duck seems not so threatened because it is not geographically isolated, not limited in habitat, and its losses due to harvest are now decreasing." In other words, American Black Ducks appear to be safe because they are spread over a large portion of eastern North America, can exist in a number of habitat types, and are being successfully protected with hunting restrictions (take limits).