Saturday, 2 September 2017

Little Stint vs. Red-necked Stint

With so many moulting adult Little Stints Calidris minuta around, I have really been wanting to get a full set of images of similarly-plumaged adult Red-necked Stints Calidris ruficollis (from worn birds with a lot of summer plumage retained to those already in winter plumage) to make some comparisons. I have been hampered by the weather (overcast, rain), and also by the fact that Red-necked Stints have proven to be far less approachable than any Little Stints for reasons I have yet to fathom (a big consideration as I am only using a 300mm (+1.4 converter) lens). After a full two days on them, I have now run out of patience, though have at least managed to get shots of one individual which fortunately is in a near-identical state of moult to yesterday's Little Stint.

The bird in question (all the photos above and below are of the same individual) has a mudded bill, but with some overlap in bill characteristics anyway between the two species this is not much of a problem. Aside from a few remaining traces of orange at the breast sides on yesterday's Little Stint (which see), there really is absolutely nothing concrete plumage-wise to readily separate these two individuals. Both share a very indistinct split supercilia (with, if anything, this feature being more pronounced on the Red-necked Stint), have whitish, mottled foreheads, obvious white eye-rings, mottled breast patches (slightly larger/more extensive on the Little Stint), and are identical in pretty much every regard through the mantle and scapulars. The only plumage feature which seems to differ between the two is the shape and length of the supercilium: long and downwards-sloping in the Red-necked Stint; shorter, straighter, and abruptly flared in the Little.

It is a surprise, then, that Little Stints in Taiwan would stand out at all, but they do, regardless of what plumage they happen to occur in. This is all down to structure. In all of the images above, regardless of posture, the Red-necked Stint has a fairly large head with a rather 'full' nape. This is only matched by Little Stint when it is hunched up, and is lost in other positions (when the head is small and square). The rear end of Red-necked Stint is noticeably long, with 'plenty of body' still to go between the legs and the undertail (whereas the body of Little tapers quite abruptly to the undertail). The legs themselves are pretty sturdy, shorter than those of Little, and rather thick-kneed (on Little, the legs are thin and rather longish). The overall Gestalt of the Red-necked Stint is of an evenly-proportioned, stout, 'flat-bottomed' peep which remains relatively level when feeding and has its shortish legs set rather centrally along its 'undercarriage'. This contrasts markedly with the 'rounded ball on long spindly legs' (which can appear dainty and elegant at times) Gestalt of Little Stint, which 'tips up and down' (sometimes wildly) when feeding and, if anything, has its legs set a bit too far back! I hope the composite below adequately captures these key structural differences (which are also apparent in the much more straightforward juveniles here). 

With this single Red-necked Stint having taken so long to photograph, it's unlikely I'll have the patience for more (though nice crisp juveniles I'm always interested in). As Little Stints for some reason tend to be easier to deal with, there may well be more of those to come before the autumn is out! Above photos taken at Tu Cheng, Tainan City 2/9/17.

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