Photo Quiz #6 Answer
By Jim Burns
A) Good photo, easy pair
We've already tackled Empidonaxes, Accipiters, and sparrows without color. Why not waders? Arguably there's never much color to work with anyway, even with the bright rufous tones many juveniles bring through our state in mid to late fall. It's usually just dark over light, and you should be keying on bill size and shape, body size and shape, and leg length. Think about it this way--when was the last time you mistook a Common Snipe for a Long-billed Curlew? We all need to gain more confidence in the jizz tools we instinctively use in less-than-subtle identification situations.
This pair certainly looks like a matched set, though the foreground bird is facing us and we have the background bird in profile. This is a small-headed, long-necked wader with a long, thin, needle-shaped bill, uniform gray above and unmarked white below. That said, we've already eliminated most of the shorebird familiesóplovers, godwits, the calidris sandpipers or "peeps", and the dowitchers. The bold head patternódark crown, wide, bright supercilium, dark post-ocular stripe, and bright white cheek eliminate those with similar shape and posture - Willet, the yellowlegs, Stilt Sandpiper.
What you may not recognize about this photograph is that we typically see this bird swimming rather than standing, and rarely do we see this bird standing still. Spinning, whirling, stabbing and slashing with that bill - now you've got it. These basic (winter) plumaged Wilson's Phalaropes were photographed September, '97 at the El Mirage ponds.
B) Good photo, difficult pair
Here's another pair of wader buddies, sharing a dry spot out of the water. Compare them to the phalaropes. The bills are shorter, thicker, blunter, lighter toward the basal half. The birds are shorter legged, shorter necked, and have a more horizontal posture. The upperparts appear uniformly dark from the forehead all the way to the tail, though perhaps not as dark as the preceding pair, and the underparts are light with heavy but uniform dark barring from the base of the bill all the way to the undertail coverts. The supercilium is light and the lores (the area between the eye and the base of the bill) are dark.
That said, we've already eliminated most of the shorebird familiesóplovers, godwits, the phalaropes and dowitchers. The short legs eliminate Willet and the yellowlegs family, the tringa. As we cursor through the calidris family, the peeps, there are some possible matches: juvenile Red Knot seems close, but the barring on our birds' underparts is much heavier and more uniform than the knot's spotting or streaking; Rock Sandpiper and Dunlin seem close, but our birds' bills are not drooped. The turnstones and Surfbird all have bills shorter than their head length, while our birds' bills appear to approximate head length.
The uniform, dark upperparts and heavily barred dark-on-light underparts really eliminate everything but these breeding plumaged tattlers, photographed in Alaska, June, '89. Despite a few scattered state records, these guys are unlikely in Arizona. If I told you the location in Alaska was the far western Aleutians, would you double take and look more carefully? Is the supercilium on the left bird really wider, longer, and more pronounced than his buddy's, or is it the angle of their heads? Is his barring really finer and less extensive, or is it the angle of the light? Is he really a little smaller, or is it the camera angle? All good questions, and a photograph, even a good/close one, can never answer questions as well as actually seeing the birds. Sometimes "photographic proof" can almost seem oxymoronic.
Here are the answers to those questions. That's a Gray-tailed Tattler on the left. Don't expect him in Arizona. His buddy, on the right, is a Wandering Tattler. Don't expect him either, but there are a few records.
C) Bad photo, easy pair
Well, the suspense is over now, and you know that both these birds are the same species. But, since this is a bad photograph, that may be hard to see. Because this pair was much farther away than the phalaropes and the tattlers, we are dealing with smaller images, more grain in the film, less detail in the birds. In fact, the birds were so far away in the original photo I would have to call it a "habitat shot." It's hard to isolate one or two waders in a large flock, especially since they tend to be frenetic feeders, constantly moving. This was one of my initial attempts to include two birds of one species in the same photograph.
These are slender bodied birds with long bills, long necks, and long legs, a combination which eliminates all the waders except Willet and the tringa family. The former, included by some with the tringines, is heavier bodied and thicker billed than our quiz birds. Solitary Sandpiper, in the right family, would show this color pattern and prominent eyering but would have much shorter legs. Unless you can convince me we might find two vagrant Asian tringines in the same pond, these have to be yellowlegs, but are they Lessers or Greaters?
These yellowlegs appear to be in somewhat different plumages, and the graininess of the photo is not helping us discern whether this is just an anomaly attributable to the angle of light. The bird on the right appears shorter legged and heavier, but notice it is deeper into the water. Its chest markings appear heavier and its bill appears slightly longer, but notice it is turned at more of a profile to the camera.
In exploring visual differences between the two yellowlegs, easily the most reliable diagnostic is the billólength, shape, and color. In Lessers the bill is the length of the head or slightly longer, whereas Greaters' bills are obviously longer than the head, sometimes half again as long. In Lessers the bills is two-thirds to three-fourths the length of the tarsus (lower leg from "knee" to foot), whereas Greaters' bills are only slightly shorter than the tarsus. Lessers' bills will be straight, slender, and all dark, whereas Greaters' will be slightly upcurved, thicker at the base, and lighter colored along the basal half.
These are both Greater Yellowlegs, photographed in September, '91 at the El Mirage ponds. If you have a chance to see the yellowlegs together, size difference should be obvious. Here are a couple interesting comparisons based on size: Lessers, in body bulk without legs taken into account, are smaller than dowitchers, and they are also smaller than Killdeer! Greaters are much bigger than those species. This wader season work more on jizz and try to rely less on the markings and colors in your guidebook. You know the old saying--"the birds haven't looked at the book". They aren't carrying cameras and shooting self-portraits either.