Some Useful Fieldmarks for Identifying Dowitchers

 

In this post I am going to discuss a few fieldmarks for separating the two dowitcher species from each other. I will start with adults in alternate plumage and then discuss juveniles. The two species are extremely similar in basic plumage and given the rarity of Short-billed Dowitcher in the county in winter, I am not going to discuss the slight differences in detail. You should always try to confirm a winter Short-billed Dowitcher by call.

To reduce the learning curve, I will be covering a subset of the available fieldmarks and focusing on ones I find especially useful or easy to use.

Alternate Plumage

When first viewing an adult dowitcher in alternate plumage, I start by assessing the overall tone of the reddish underparts and how extensive this coloration is on the underparts. In Long-billed the underparts tend to be more brick-red and this color extends all the way through the vent. Short-billed, on the other hand, has more orange-toned underparts and this coloration extends to belly, but the vent and rear flanks are white. The local subspecies of Short-billed Dowitcher also tends to average heavier dark flank barring, which is accentuated by the whiter background. However, note that Long-billed Dowitcher, especially in spring, can often show heavy flank barring as well.

Once I have used the above criteria to make a provisional identification, I then try to confirm the identification by looking at the sides of the upper breast/lower foreneck. These have short dark-barring in the case of Long-billed Dowitcher and dark spotting in the case of Short-billed. This feature seems to survive plumage wear on the breeding grounds and is usable in both spring and fall migration. Note that, especially in spring, both dowitcher species can show spotting and barring on much of the underparts, so it is critical to look in the correct place. I have highlighted exactly where to look in the photographs below.

 

Three alternate (or mostly alternate) Long-billed Dowitcher (BH). Note the more brick-red tone to the underparts and short dark barring on the sides of the upper breast/lower foreneck (ringed in green). Avoid getting distracted by spotting on the center of the breast/foreneck.

 

 Two alternate Short-billed Dowitcher (PS, LS). Note the more orange-red tone to the underparts and spotting on the sides of the upper breast and foreneck (ringed in green). Avoid getting distracted by all the barring on the sides of lower breast and flanks.

 

Juvenile Plumage

In juvenile plumage, there is a significant average difference in the brightness of the overall appearance of the two species, at least by the time they reach Santa Barbara County. This is due to two factors: firstly, Short-billed Dowitchers are brighter on average; secondly, Long-billed Dowitchers have a more rapid molt from juvenile plumage and are more advanced into (duller) basic plumage when they arrive in the county.

In particular, the orange-buff markings on the back and scapulars (and tertials and greater-coverts and even the crown) are more extensive on the Short-billed Dowitcher.  In contrast, these feathers on juvenile Long-billed have duller darker rufous markings that are also less extensive on average. The net result of this is that at long range, juvenile Long-billed tends to look rather dull and uniform above, whereas juvenile Short-billed shows an obvious bright ‘saddle’ or back. I do occasionally see a juvenile Long-billed with more extensive and more buffy scapular markings, very similar to those of Short-billed, but such birds are a small minority.

A second factor impacting the relative brightness of juveniles is the breast and upper flank color. Juvenile Short-billed is usually extensively buffy, sometimes very bright. While these buff tones are subject to fading from mid-September onwards, they are typically brighter even then than most Long-billed Dowitchers. Juvenile Long-billed tends to have more restricted buffy tones and often quickly molts the breast to the gray of basic plumage, generating an even duller appearance.

Two juvenile Short-billed Dowitchers (ringed in orange) and two juvenile Long-billed Dowitchers (ringed in white) (PS). Although these Short-billed Dowitchers are rather faded this late in the season (October), note the orange-buff spots in the tertials, the brighter and more extensive orange-buff markings on the back and the more obvious buff wash on the breast.

Beyond the general brightness, the specific “go-to” feature to separate juvenile dowitchers is the pattern of the tertials. On Long-billed Dowitcher, the tertials are plain unmarked gray with a very narrow pale fringe. On Short-billed, the tertials are gray-brown with some orange-buff internal markings.

Juvenile Short-billed Dowitcher (BH). Note the obvious orange-buff markings in the tertials (ringed in white)

Juvenile Long-billed Dowitcher in transition to basic (PS). Note the plain gray tertials with a narrow pale fringe (ringed in white). These are the juvenile tertials, not basic ones. Generally, the tertials seem to be among the last juvenile feathers to be lost on both species.

As ever with these two species, there are some caveats with this feature. I have on a couple of occasions seen juvenile Long-billed Dowitchers show a few small reddish dots or dashes just inside the edges of the tertials. This is so infrequent that you can assume that a juvenile dowitcher with internal markings on the tertials is a Short-billed. If these markings are minimal and the bird has other features favoring a Long-billed, then I would suggest trying to hear the bird vocalize.

More problematic are juvenile Short-billeds with relatively or very indistinct markings in the tertials. Very rarely (certainly <1%) I have come across juvenile Short-billed Dowitchers with completely unmarked tertials. Much more frequent (10-15% of juveniles) are birds where the internal markings are quite dull and are difficult to see at medium-to-long range. However, the markings are there if you can get good looks or photographs.