Tuesday, September 23, 2008

19th September 2008: Tanjung Tokong, Penang, Part 3: Sandpipers and stints and other stuff

As the tide came up a nice selection of waders congregated on the nearby sandspit.

Calidrid collection. I managed to get these four Calidris sandpipers to pose photogenically - largest at the back, smallest at the front! Ignoring the partially obscured birds, they are Great Knot, Curlew Sandpiper, Broad-billed Sandpiper and Red-necked Stint.

This pic of adult Curlew and Broad-billed Sandpipers nicely illustrates the difference in bill and leg length.

Curlew sandpipers stand out in flight due to their (mostly) white rump. Here are two with a Broad-billed and a couple of Red-necked Stints.

Actually, I hadn't realized till today that, at least in worn breeding plumage, Curlew Sandpipers can have quite extensive dark spotting on the rump and uppertail coverts. The left hand bird even seems to have the faint beginnings of a central rump stripe, more typical of other small calidrids.

I didn't see any Little Stints today, but I was pleased to see some Little-like Red-neckeds. Here. the left hand bird seemed a little more 'leggy' than its colleagues. The consistency of the leg length as it fed suggested the length was actual rather than subject to posture.

Another Red-necked that appeared to have quite a well-streaked breast - at least the sides. The dark feather shafts on the rear flank, the short tarsus and short, straight, tubular bill are all typical of Red-necked however.

A more typical and obvious adult Red-necked Stint.

My first juvenile Red-necked of the season. I was surprised to see that it was pretty worn; the buff edges and white tips to the scapulars have already largely worn away.

High tide is often the time when waders will seek out some fresh or brackish water to spruce up their plumage.

Just above the tail is the uropygial gland, which secretes an oil that the bird uses to waterproof its feathers. First it smears the oil over the bill tip.

Then it applies the oil to the feathers by rubbing them with the bill. More pics of waders and their uropygial glands can be found here.

Here's a close-up of the tail. The legendary paper on the Identification of Peeps and Stints by Grant and Jonsson gives one of the 'in-hand' criteria for separating juvenile Little and Red-necked Stints as the pattern of the pale fringe on the central pair of tail feathers. On Red-necked, if it is present at all, the fringe is confined to the outer web. The dark feather-centre is rounded at the tip.

On Little, the equivalent pair of tail feathers, viewable here, have an obvious pale or rufous fringe on both webs at the tips of the feathers. The dark feather-centre typically breaks the fringe at the tip as a sharp point.Hmm! There's something I didn't know before!

Something simpler - a juvenile Common Sandpiper creeping up on dinner!

A couple of pics to finish off showing the expansion of the roost as the tide came up.

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