July dowitcher


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Posted by Dennis Paulson (192.124.98.228) on September 03, 2002 at 14:32:56:

Hello. Joe asked me to comment on the dowitcher photographed 27 July 2002 in San Diego, CA. I posted a response to Matthew Kenne's comments about what I had written in my 1993 shorebird book, but I'm new to this format, and I'm not sure whether I actually sent it correctly!

If my life depended on a correct call for this bird, I'd come down on the side of Short-billed. If a normal adult bird, I think it's in full body molt way too early for Long-billed, which starts molting as much as a month later than Short-billed, at least in my part of the country (Pacific Northwest). In our museum, we have lots of fall LBDO, and those from late July are in full alternate plumage, while we don't see much really obvious molt (of the type shown by the bird in question) until late August.

I think I can see enough of the tail that it looks like a Short-billed tail. However, it's often difficult to know if you're looking at the rectrices or merely the upper tail coverts.

I commented in my earlier (lost?) message that the wing projection isn't a diagnostic field mark to distinguish these species, so I wouldn't make anything of the fact that the wing and tail seem equal.

The bill is in the range of either species. I also don't think much of the mark that was mentioned by one contributor concerning the curvature of the bill. I don't think that little droop toward the end is characteristic of either species but instead is a mark of individual variation. Has anyone ever got the impression that we may try too hard at times to find differences among species?

I don't see anything about the plumage, with the possible exception of the tail, that's a dead give-away to species. There are not enough new breast feathers to be sure whether they will be typical of the plain LBDO or the often spotted SBDO. On the other hand, the feathers on the upper sides that are diagnostic of species have been replaced!

How about the lower sides? Well, I'm not sure if those spotted feathers are left over from alternate plumage or represent fresh basic plumage, so it's hard to use them as diagnostic. I don't think there is any real difference between the species in the feathers of the lower sides anyway.

How about the belly? Again, I'd say that not knowing how many of the feathers have been replaced, we can't know exactly what the full alternate belly pattern was, so we can't distinguish between the more heavily spotted SBDO and the more lightly marked LBDO.

I'm afraid I'm left with the state of molt on that date as my only reasonably good criterion for identification!

Dennis Paulson


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