Thursday, April 21, 2011

4th April 2011 (pm): Kapar - godwits and dowitcher

I've finally waded (!) through over 1500 shots taken during the afternoon tide, and, since there's no way to put the best of those into one post, I'll divide them up into similar species posts, starting with the godwits and co. Numbers of both Bar-tailed and Black-tailed were well down on my March totals , just 600 of the former and 500 of the latter.

Summer plumaged Bar-tailed (above) and Black-tailed (below). People get confused between these two species, but they are really quite different from each other, structurally, in flight, and in all plumages, as I hope to show. In breeding plumage, Bar-tailed has chestnut which extends all the way to the vent, while on Black-tailed, this colour is replaced by black bars from the breast down. Note also the different bill shapes - tapered and upcurved in Bar-tailed and blob-tipped and straight (or even slightly 'drooped') in Black-tailed.

A Black-tailed with a couple of Bar-tailed behind. In all plumages, Bar-tailed has pale buff wing coverts with darker shaft streaks, a pattern reminiscent of Eurasian Curlew's, whereas Black-tailed coverts are relatively plain dark grey-brown (not very visible in this shot). The difference in bill shape is obvious here. Black-tailed bill is pink basally in non-breeding plumage, but turns orangey in breeding plumage.

Bar-tailed is substantially larger and longer billed than Black-tailed in East Asia. The races here are 'menzbieri' (Bar-tailed) and 'melanuroides' (Black-tailed). In this pic you can just about see that Black-tailed is markedly longer-legged than Bar-tailed.

A couple of pictures to sharpen your skills. One has a lone Black-tailed in among the Bar-tailed; the other has two Bar-tailed among many Black-tailed. I'm sure you can figure it out!

In flight, the differences are even more obvious. For a start, the different leg lengths give the two species very different shapes. Black-tailed looks like a flying cross, with the long leg projection behind the wings. Bar-tailed, on the other hand, looks front-heavy, with very little toe projection beyond the tail. So you should be able to see 1 Bar-tailed and 3 Black-tailed in the photo above.

In flight from above, Black-tailed is one of the most striking of all waders, with the broad white wingbar and black and white banded tail. Bar-tailed is relatively plain above, with just a white wedge running up the back. Note that the Bar-tailed in this pic doesn't have much of a barred tail, but that's another story!

From below, they are just as different. Bar-tailed has a finely barred underwing, which looks an unremarkable grey at a distance.

Black-tailed has a clear pearly-white underwing framed by a dark leading and trailing edge to the wing - quite different!

Now that we have the differences sorted, here are a few more shots of Bar-tailed.

Breeding plumaged birds have less pink on the bill than non-breeders, and in some well-marked birds (males?) the bill turns almost completely dark (see the rear bird). So a godwit-like bird with an all dark bill at this time of year is not necessarily a dowitcher!

Non-breeding plumaged Bar-tails, looking typically 'pale and streaky'!

One reason why Bar-tailed Godwits' bills look so tapered is that the upper mandible overlaps the lower by a few millimeters.

Interesting to compare bill colouration between birds in breeding and non-breeding plumage.

Back to Black-tails, looking like so many pairs of chopsticks! You can see a few plain grey-brown non-breeders here.

Caught in the low evening sun.

Assorted flying Bar-tailed Godwits.

And some Black-tailed.

I spent a total of perhaps 16 hours over four visits (two tides per day) studying and photographing the waders at Kapar. I asked myself a few times during that time - is it possible that I could have missed anything? The answer was given me when I was going through my photos weeks later!

Yup - I missed this one at least! Captured on camera at sunset on 4th, yet not seen 'in the flesh' on the 4th or the 5th - one Asian Dowitcher (lower left). Looks like it was coming into nice plumage too!

Completely fortuitously, I managed to capture all three species in one shot, albeit not in sharp focus! Note the distinctive 'tubular' bill of the dowitcher (centre), unlike either the pointed, upswept Bar-tail's bill or the blob-tipped droopy bill of the Black-tailed. The underwing is distinctively different too.

And the toe projection beyond the tail falls nicely between those of the two godwit species!

Getting tired of waders yet? Hope not - there are many more to come!


Wai Yien said...

always enjoy reading you post especially when you are detailing the differences between one species to another, always very revealing even for non waders fan like myself.

Kate said...

Wonderful images. Just superb!