Date: 6/19/20 11:12 am
From: larspernorgren <larspernorgren...>
Subject: [obol] Re: White-rumped vs. Semipalmated Sandpiper?
This came up with curlews 2 months ago. Bill length among individuals of the same species varies a great deal and much of it is gender-based. It is common to see a flock with some bills 30% longer than others. Very tempting to ascribe multiple IDs.Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Noah Strycker <noah.strycker...> Date: 6/19/20 10:59 AM (GMT-08:00) To: Robert O'Brien <baro...> Cc: obol <obol...> Subject: [obol] Re: White-rumped vs. Semipalmated Sandpiper? In spring, a White-rumped Sandpiper (in breeding plumage) would have dense, crisp lines of streaks across the breast and down the flanks, and the base of the lower mandible would be light fleshy colored. A White-rumped's bill should be more tapered toward the tip, and appear a little droopy. As Bob pointed out, the structure of this bird also doesn't fit the long-winged, drawn-out profile of a White-rumped (which is structurally closest to Baird's, befitting those two species' long-distance migrations).There is some variation in bill length/shape in Semipalmated Sandpipers (though not as variable as Westerns); relying on bill proportions to ID calidris sandpipers is tricky at best.Good birding,NoahOn Fri, Jun 19, 2020 at 9:09 AM Robert O'Brien <baro...> wrote:Now maybe since we mostly see juvenile Semi Sands in fall in Oregon, perhaps juvenile Semi Sands have blunt billsthat later get pointed as they mature? Or is this going off the deep end?Bob OBrienOn Fri, Jun 19, 2020 at 9:00 AM Robert O'Brien <baro...> wrote:Well, I dunno.  That is a often-mentioned mark for White-rumped, but I think this guy fits into that slot OKHere is an overlay with a White-rumped from Macaulay library, sizing more or less the same and lining up the eyes.Has anyone ever seen a Semi Sand with a sharp bill like this in Oregon?  Any photos?Bob OBrienOn Fri, Jun 19, 2020 at 8:48 AM Bob Archer <rabican1...> wrote:Hi:Structure is wrong for a White-rumped, they have long primaries well past tertials and  the tail. Bob ArcherOn Fri, Jun 19, 2020 at 8:39 AM Robert O'Brien <baro...> wrote:While looking for something else I accidentally came across this photo, taken this month in British Columbia as a Semipalmated, I'd suggest a White-rumped, based upon the narrow, sharply-pointed bill.But, seems like I recall some discussion some time suggesting that eastern Semipalmated have more pointed bills than the ones we get here on the West Coast, which can usually be IDed from Western just by their blunt bills.No discussion of the ID in the eBird report and an easy mistake to make, unless you looked for the rump in takeoff/flight.  And since White-rumped would not be expected, who knows?What do people think?Bob OBrien  Carver OR

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