Saturday, September 05, 2009

5th September, 2009: Teluk Air Tawar, Penang

My main problem at the roost today was that the birds were too close! I had set up my digiscoping gear and at times I could not get a full bird in view.

A scopeful of Lesser Sand Plover! This is a juvenile, and at least this shot gives a clear view of feather wear. The feathers most exposed to the light seem to be the most heavily abraded. The lower tertials, greater coverts and secondaries look much neater and fresher than the relatively heavily worn scapulars, median coverts and upper tertials.

Another juvenile, a little further away!

I see the odd bird like this, where the old median coverts seem to have disappeared entirely, exposing the bases of the greater coverts. The lines of white-tipped feathers are the new lesser and median coverts growing. My guess is that this is a 1st summer bird moulting into 2nd winter plumage. I'm basing that guess on the extreme wear of the upperpart feathers. Odd that the outer primaries seem rather fresh though.

Many birds were panting in the extreme heat reflecting off the packed laterite, revealing the serrations along the cutting edges of the bill that help them hold onto their prey.

I was also intrigued to see that many birds appeared to be holding drops of water in their bills. The place has been bone dry, with no rain for days, so they hadn't just picked it up. At low tide the birds are feeding in saline habitats, where I doubt they can drink the water. So come to think of it, how do these birds survive without fresh water, and if they can't, where do they get it from when it doesn't rain?

I ODed a bit on Broad-billed Sandpipers!

I saw my first juvenile Broad-billed Sandpipers, Red-necked Stints and Curlew Sandpipers of the year today. The latter didn't hang around long enough to be photographed, and my shots of fresh juv Broad-bills weren't sharp. However, some of the young Broad-bills were already quite advanced in moult to first winter plumage, like this bird.

The strength of the breast band on these young birds varies from being quite heavily streaked to barely streaked at all, as on this bird.

Here's a nice angle on the juv-1st winter bird, with an adult to the right for comparison. The lines of grey feathers on the mantle and lower scapulars are the 1st winter feathers. Those beautiful pale fringes on the coverts will gradually wear away as the season progresses.

This adult has something wrong with the crown feathers, giving it a very odd head shape.

Here's something I learned today. Broad-billed Sandpipers have very long hind toes compared to most true Calidris sandpipers, as long as Long-toed Stint's! Here's a comparison with a Red-necked Stint (left).

Three adult Curlew Sandpipers at different stages of post-breeding moult.

There was another adult Little Stint today - my third of the southward migration. The bright chestnut fringes to the lesser coverts and inner greater coverts of this bird made it nice and easy to pick out. It's also long-legged and long-winged compared to Red-necked.

A couple of superficially similar Red-necked Stints at a similar stage of moult lack chestnut tones to the coverts. The blackish shaft streaks near the vent of the lower bird are diagnostic of Red-necked when present.

I noticed that the Red-necked Stints were looking unusually long-legged today. They seemed to be pulling themselves up away from the heat coming off the ground as far as possible!

A couple of plovers to finish. A nice freshly-moulted adult Greater Sand Plover - interesting how large the eye looks compared to the Lessers behind... (there are a few other Greaters in the video clip).

...and a lone Kentish - presumably the same bird as on 24th Aug.

I stayed till the birds set off for the mud as the tide fell. It was interesting to watch the build up to departure - increased restlessness and calling, and lots of wing-stretching and wing-raising leading up to take-off.

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