July 2018 Photo Quiz
Click photo to enlarge.
Flying passerines can be identified, too!
Our departing quiz bird may annoy some birders, as it did not stick around long enough to be identified. However, such birds can often be identified, either shortly after take-off or waiting for it to land, again. Since we could wait all day and this bird wouldn’t land, again, we will need to see what we can do about gathering information that can hopefully lead to its ID.
First off, the short wings relative to the body size indicates that the beast is small. This is true and oh-so-useful in determining at least rough size of an unknown bird. That is because, all else being equal, a bird that is 20% larger than another bird will need more than just a 20% longer wing span in order to equal the flight performance of the smaller bird, as body mass increases as a cube, not linearly. Granted, “all else being equal” is virtually never true in biology, but this rule-of-thumb still provides expert birders with a good sense of an unknown bird’s relative size, even if that birder doesn’t recognize the fact.
Perhaps the first important key to this bird’s ID is noticing the tail spots -- pale (usually white) patches of color on the inner webs of tail feathers, aka rectrices, that contrast with most or all of the other portions of those pale-patched feathers. Note that the boldfaced, red-font aspect of that point is critical – the white outer webs of the outermost rectrices of Western Kingbird or Horned Lark are NOT tail spots. Because of how bird tails fold, those spots are visible on the folded tail only from below. Logically, then, the central pair of rectrices does not sport tail spots, else they would be visible from above, even on the folded tail.
The bird’s small size and the presence of tail spots may start us down the warbler road, as the family Parulidae houses the lion’s share of the ABA-Area passerine species sporting tail spots. We can certainly rule out Barn Swallow, one of the few other passerine species with tail spots, as well as the various nuthatch species. The bit of yellow underparts plumage rules out gnatcatchers and the few sparrow species with tail spots.
Please submit the correct Common or English name exactly as it appears in the ABA Checklist.