the infamous Del Mar whitish-backed Whimbrel (and how to eBird the record)

Many of you went to see the odd Whimbrel on the beach in Del Mar that was present from 11-13 July. While it was last reported early on the 13th, it may or may not in fact still be around, as there have been no reports since then suggesting any careful search. This bird had white on the lower back (not truly on the rump), which begged the question as to whether it was one of the Old World forms, presumably Asian (Siberian) variegatus based on range and on the somewhat limited amount of white. (European phaeopus is even a bit more distinctly different from our North American hudsonicus.) Some of you eBirded it as “Whimbrel (White-rumped)” which covers all the Old World taxa. Some eBirded it specifically as “Whimbrel (Siberian).” Some as just generic “Whimbrel.” And perhaps a few of you just threw your hands up and haven’t submitted it yet as anything! It is the consensus of a good number of us that this bird does not fit neatly into any category. It is not a typical variegatus, as the amount and shape of white seems off, and virtually all other characters seem OK for a typical North American Whimbrel, including the underwing pattern and the obvious buffy tones to the underwing and tail. Yes, the bird did look slightly paler/colder in overall upperpart body tone than most of the many Whimbrels assembled, but there were certainly at least a small number of other North American birds present there that were a match in exact color. As those present at the site know, it was virtually impossible to know which bird it was until you could see the white on the lower back, and then follow it around. Suggestions on what the bird was range from an intergrade/hybrid between hudsonicus and variegatus (although precious few other characters looked intermediate), to a true variegatus, to simply an aberrant-plumaged regular hudsonicus Whimbrel. Add to these issues the fact that eBird currently does not have any way for a user to submit such a bird without declaring it one taxonomic group or the other or to submit it simply as a generic Whimbrel and then conceivably have this interesting bird “lost” amongst the thousands of records of typical Whimbrels.

We San Diego County eBird reviewers are, in fact, asking all of you who submitted this bird as some form or another to please change it to just generic Whimbrel for now, as that is the only safe entry. As a reviewer, we may be able to “tag” any photos associated with this record in the Macaulay Library, and/or via “MerlinVision,” as “aberrant” or some such so easier to find at any later time. But the bottom line is: if this record needs to be revisited, it would not be difficult to simply search out all Whimbrel submissions from Del Mar between 11-13 July 2024.

So, to repeat, if you have submitted this bird via eBird, please change it to generic Whimbrel. Any reports remaining as something else after a week will be sent back to the observer to be changed, and then, in the end, invalidated if still remaining.

Thanks for your understanding!!

–Paul Lehman and fellow eBird reviewers, San Diego