Answer:

From the bill shapes alone we can immediately eliminate many possibilities: they are not finches, sparrows, blackbirds, thrushes, swallows, flycatchers, or other passerines. Likewise just from the bills we can rule out raptors, doves, gulls, ducks, seabirds, and most other bird families. Of those bird families that might have long thin bills, most of them (like hummingbirds, ibis, storks, grebes, herons) have a very different overall shape than these birds, which are horizontally-oriented, short-necked, and walking on thin legs. So we arrive at shorebirds, a group of birds that often (but not always) forages at the edge of the water.

It’s always hard to get a feel for the size of birds in photos, but these seem very small. Compare the size of the birds to the bubbles in the water. So we are looking at small shorebirds.

The smallest shorebirds are the smallest sandpipers (often called “peeps”) and a few small plovers. Compared to the quiz birds, the smaller plovers (Semipalmated Plover, Snowy Plover, Piping Plover) have smaller, shorter bills, larger eyes, and different plumage (including neck rings or partial neck rings). Even the larger plovers (like Killdeer or Black-bellied Plover) have shorter bills that aren’t pointed downward. So we turn to the peeps.

But wait…before we move on to the peeps we should consider another shorebird that is slightly larger than peeps and similar to them—the Sanderling. Sanderlings in basic (nonbreeding) plumage are easy to identify: they are very pale gray on top and white below, with some black at the bend of the wing, and black wingtips. But in alternate (breeding) plumage, Sanderlings have rich rufous on the head, neck, and breast, often with a ‘speckled’ look. And in summer there can be Sanderlings molting from alternate to basic, which can look confusing. Neither of the quiz birds has the rufous speckled look of a Sanderling. The right bird has some rufous on the cap and cheek, and a little on the back, but the breast streaking is more brownish. It also has little dark chevron markings that go all the way down the sides of the breast partially onto the belly and past the legs; even breeding Sanderlings are all white below the breast. And the right bird’s bill is a little too long and droopy and thin at the tip for a Sanderling. The left bird has too little rufous and too much brown in the plumage, with too even of coloration and not speckled like Sanderling. Also the left bird has a hind toe, which Sanderlings lack.

So let’s get back to peeps. First look at the right bird, the one with the longer downcurved bill. Baird’s and White-rumped Sandpipers would have long primaries extending past the rear end, which we don’t see. The other North American peeps, as well as the Stints, all have much smaller bills. So we are left with Western Sandpiper, which is common in LA County in fall. Adult Western Sandpipers have rufous on the head and cheeks, mottled backs, black legs, and can have chevron markings on the underparts.

Now what about the bird on the left? It has a much shorter bill than the Western Sandpiper, and looks smaller and a bit browner overall. It has some streaking on the breast that looks like a slight dark wash. It seems to have slightly lighter-colored legs. So it is tempting to call this bird a Least Sandpiper. However, look carefully at the bill. A Least Sandpiper has a small bill that is very thin and pointy at the tip, but this bird has a short but blunt bill. And Least Sandpipers are even browner than our bird. Finally, the partially-webbed toes can be seen on the left leg of our bird. The short blunt bill, the uniform brownish-grey upperparts, and the slight breast streaking are good for Semipalmated Sandpiper. It seems the lighter-colored legs might be a result of light-colored mud or dryness; notice that the feet are darker. See the photo below, which shows the same Semipalmated Sandpiper on the left, and a Least Sandpiper on the right. Notice especially the difference in bill shape.

It is often possible to tell the age of a shorebird even if you don’t know its species. In fall (and for many shorebirds “fall” includes what we usually think of as summer), juvenile shorebirds have not had their feathers for very long, so they generally have very neat-looking upperparts, clean and crisp with every feather nicely outlined, often producing a scaled appearance on the back. Fall adults, on the other hand, have messier-looking upperparts. Based on those characteristics, these two birds are adults.

Congratulations to Calvin, Frank, Patricia, and Susan for figuring out the correct species!

–Mark