The Identification of Dowitchers in Santa Barbara County

 

Over the years I have been asked about how to separate dowitchers by a number of local birders as well as seeing requests for help with dowitcher photos posted on local on-line forums. As probably the most active birder in the county with respect to looking at shorebirds, I wanted to put down some thoughts here on my process for separating these two species. Also, as a local ebird reviewer, I would like to reduce incidences of less experienced observers making obviously incorrect claims of the species.

There is already a significant amount of published material available on how to separate these two species. This paper by Lee and Birch is pretty comprehensive:

https://www.aba.org/birding_archive_files/v38n5p34.pdf

I will cover a subset of the identification criteria presented in the above paper, so you can focus on learning a few key features. If you can effectively master these features, you should be able to identify 90%+ of birds correctly. Given that both species are regular in the county, making occasional misidentifications is not a big issue, as long as you have an understanding of their status during the year.

I will start off with some simple tips that mostly focus on habitat choice, vocalizations and status in the county and don’t require learning a mass of plumage details and associated caveats. Using these will make it much less likely that you will unwittingly report one of the species at a time or location or in a quantity that is unlikely. If you don’t bird in Santa Barbara County, note that the status of the dowitcher species is different even in neighboring Ventura County, so avoid applying the temporal and numerical data away from Santa Barbara.

Tip #1: Habitat choice

There is one very reliable rule when it comes to habitat. If a dowitcher is feeding on a beach, it’s a Short-billed. In my 25 years of birding in the county, the one time I have seen Long-billed Dowitchers on a beach was where a pipe was releasing freshwater on to the beach. Even when there is creek or river mouth, the Long-billed Dowitchers will inevitably be on this and not feeding along the beach. If you really think you have a Long-billed Dowitcher on the beach, make sure you get high-quality images or hear the vocalizations.

In any other habitat situation, you generally cannot be sure of which species is present based on habitat choice as Short-billed Dowitchers will freely utilize most suitable shorebird habitats during migration. During the winter, Short-billed Dowitchers are largely confined to intertidal mudflats. However, this habitat distinction is rarely useful in Santa Barbara, because of Tip #2 ….

Tip #2: Dowitchers in winter

A dowitcher seen in winter in Santa Barbara County will be a Long-billed. This is not as ironclad as tip #1, since Short-billed Dowitcher very rarely do winter at locations like the Santa Ynez River Mouth or Carpinteria Saltmarsh, but not more often than once every few years. I also had a one-off presumed late migrant on the beach at Coal Oil Point in mid-November one year.

I should define exactly what I mean by “winter”. Short-billed Dowitcher occurs regularly well into October and migrants can linger as late as the last week of October. Birds that linger into November are pretty exceptional and may end up wintering. Short-billed Dowitcher can appear on spring migration as early as February 10 and are regular by March. In summary, you should assume any dowitcher seen from early November to mid/late-February to be a Long-billed, unless it’s on a beach of course! If you believe otherwise, you should try to verify the identification by vocalizations, as the basic (winter) plumages are the most difficult to separate.

Tip #3: Juvenile Dowitchers in August and early September

In the next post, I will cover how to separate juvenile and adult plumages. Once you can recognize juvenile plumages, you can make a further pretty safe assumption on a bird’s identification based on the time of year. In Santa Barbara County, juvenile Short-billed Dowitcher can appear as early as the very end of July and are common through August and September, peaking in late August and early September. They are regular to about Oct 15-20. In contrast, juvenile Long-billed Dowitcher tend not become regular until September 10 onwards. They start to become common around the last week in September and will usually outnumber juvenile Short-billed Dowitchers after that date. There are earlier records of juvenile Long-billed Dowitcher in the county and I have even found a couple in very late August. However, these are unusual and any claimed juvenile before September 7 or so should be well-documented.

Tip #4: Flocks of dowitchers from July to mid September

Long-billed Dowitcher formerly occurred in good numbers (low hundreds) in the Santa Maria. However, habitat degradation there has resulted in counts that rarely surpass 100 these days. In addition, some of the better locations are not publicly accessible anymore. The lack of consistent quality habitat means that adult Long-billed Dowitchers, which have learnt where reliable feeding areas can be found, now largely avoid Santa Barbara County. In fall migration, it is now rather unusual to see more than a handful of adult Long-billed Dowitchers. The larger counts today are invariably first-year birds that arrive as juveniles and then spend the winter in variable numbers. This means that larger (>5 or so birds) flocks of Long-billed Dowitchers occur from about Sep 15-20 onwards and through into spring.

In contrast, adult Short-billed Dowitcher still occur at favored locations like the Santa Ynez River Mouth in quite good numbers (e.g, 20-30 birds or more) during July and August. Of course, any Long-billed Dowitchers will often attach themselves to such flocks, so you can’t assume a larger flock is all Short-billed. However, you can be pretty confident that most are.

In spring, flock size is less useful as Long-billed Dowitchers can in occur in slightly larger flocks, while Short-billed tend to be less common than in fall.

Tip #5: Location

Long-billed Dowitchers occur regularly throughout Santa Barbara County pretty much throughout the year except from late May to mid-July, although they are rare in the Cuyama Valley in winter due to limited and sometimes frozen habitat. As well as being absent in winter, Short-billed Dowitchers are highly coastal during spring migration. So if you suspect a Short-billed Dowitcher at Lake Cachuma or similar inland location during spring, be sure to get good documentation. In fall migration (which can start as early as late June for Short-billed Dowitchers), Short-billed Dowitchers regularly occur at inland locations, especially in the case of juveniles.

Tip #6: Vocalizations and use of playback

The easiest way to certainly separate the two species is by the calls, which are very distinctive from each other. Long-billed has a sharp ‘keek’, whereas Short-billed has a mellow ‘tu-tu-tu’. Occasionally a Long-billed Dowitcher may give a short series of weaker ‘keek’ calls that are sometime confused with those of Short-billed by less experienced observers.

In the past, I occasionally resorted to flushing difficult birds to confirm their identification. In addition to the fact you disturb the bird, there are other drawbacks to flushing a bird. First, the bird might not call when you flush it. Second, dowitchers often occur in mixed flocks and Long-billed have a greater tendency to call when flushed than Short-billed. Therefore, you might flush a mixed flock and only hear Long-billed Dowitcher calls, even when most of the flock consists of Short-billed Dowitcher!

Fortunately, I recently discovered that dowitchers will commonly respond to playback of their calls. Playback is very effective because you can see which birds in a flock call in response to it. I have instances where I have had a suspected mixed flock and used playback to confirm the birds I thought were Short-billed actually were and then confirm the Long-billeds by playback of their call. Playback is a great tool to use to elicit vocalizations to determine the identify of any bird that you are unsure about.

One final note on vocalizations. The call of Black-necked Stilts is rather similar to that of a Long-billed Dowitcher. If the former species is present, make sure that any ‘keek’ calls you here really came from a dowitcher before assuming there are Long-billeds present.

Tip 7: Do not identify dowitchers using only structural features.

I have been surprised by how many novice birders claim dowitcher identifications based on the bird having a ‘flat-back’ or some other structural feature. While there are subtle structural differences between the two species, these are best appreciated when they are in direct comparison and, even then, seem to show some individual variation. Most of these structural differences are covered in the Birch and Lee identification article but I would recommend birders master the plumage features covered first prior to delving into structural differences.

Having mentioned that I am not really a fan of using structural features, I am going to confess that I often use bill length in the identification process. I will start with a warning here: bill length is NOT diagnostic for the great majority of dowitchers. However, it is often a useful starting point. For example, I will often scan a flock looking to see if any birds have particularly short or long bills. It can also be useful for understanding the identification of distant larger flocks. For example, if a flock has no birds with very long bills and a number with obviously shorter bills, you can reasonably conclude that the flock is (at least) largely Short-billed Dowitchers.

Obviously judging what is a shorter bill and what is a longer bill takes some practice, but you can peruse on-line images to get a good idea and study wintering birds (which will almost always be Long-billed) to gain experience.