On Saturday the 9th, Sandy spotted two squabbling flycatchers as we heard the clear call of the year's first Least from a different direction while we were walking up the bridle trail from the Ross Drive bridge toward the maintenance yard in Rock Creek Park. After consulting Sibley I'm convinced the squabble was between an early Eastern Wood-Pewee and an Acadian. One had an eye ring and flicked its broad tail; the other sat more horizontally (when it wasn't squabbling) and had no eye-ring at all. We fantasized about a Willow but I doubt it.
The important detail is that the two birds were both about the same size. It's worth remembering that wood-pewees are little larger than Willow, Alder, and Acadian Flycatchers -- in fact, that helps explain the squabbling as it seems to break out most frequently among similar-sized birds, anything else tending to fall in the categories of harrassment (large on small) or mobbing (small on large).
It reminds me that on recent trips out west I've started to find size one of the best guides to empids. Apart from Buff-Breasted, they seem to me to fall into three discernible categories: 1) Hammond's, Dusky, and Least the smallest with the narrowest and most tapered tails; 2) Pacific-Slope, Cordilleran, and Yellow-Bellied a bit larger and all brighter-colored yellow than the rest, the bright coloring perhaps selected because differentiation by size would be hardest for these birds; and 3) Gray, Acadian, Willow, and Alder the largest with the broadest, straightest tails.
The size categories turn out in retrospect to be the best argument for an Acadian rather than a Least squabbling with the early pewee on Saturday, at any rate.
As for the recently-aggrandized equitation field, no less an authority than Claudia Wilds described it as follows: "Passing the entrance to Ross Drive, you reach an even larger lawn with a corral." Hmm, how did that endearing corral become an intimidating equitation field? Will the maintenance yard become a resource management operations sector?
David Apgar |