Friday, April 22, 2011

4th April 2011: Kapar - Tringa sandpipers

Sandpipers belonging to the genus Tringa are medium-sized, elegant waders, often called 'shanks' on account of many of their names, and due to the fact that the colour and length of their 'shanks' (ie legs) is one important key to their identification.

Seven species have been recorded in Malaysia, all as migrant or vagrant visitors: Common Greenshank, Nordmann's Greenshank, Marsh Sandpiper and Common Redshank are pictured here - just about - too bad the Marsh Sandpiper wouldn't cooperate!

Nordmann's Greenshank is exclusively found in coastal habitats, Common Redshank mostly so, while Common Greenshank and Marsh Sandpiper are equally happy in brackish and even freshwater environments; Wood and Green Sandpipers are both freshwater-preferring species (the latter is a vagrant); while Spotted Redshank is probably more likely in intertidal areas, but is a very rare visitor. Nordmann's Greenshank is classified as Endangered by BirdLife, having an estimated world population of around 500 birds.

There are three 'Tringa-like' sandpipers to complete the Malaysian picture - Grey-tailed Tattler, Terek Sandpiper and Common Sandpiper. All have much shorter legs than genuine 'shanks'.

Common Redshanks (seen here with two Tereks) are the default Tringa in Malaysian coastal environments. In fact, in terms of numbers, they are the second commonest wader species after Lesser Sand Plover. Easily identified by their red 'shanks' and generally brown upperparts, though these can be a wide range of brown tones, from cold dark mud-brown to a rich foxy chestnut, depending on plumage and race.

A breeding plumaged 'craggi' race Common Redshank, at the foxy end of the brown scale!

Occasionally you'll come across a Redshank with less red legs - usually there's a least a hint of orange. These may be young or sick birds.

In flight, they have a broad white trailing edge to the wing and a white wedge running up the back...

White underwing...and red-orange legs!

A few more here! In amongst them, you should be able to find: Whimbrel, Black-tailed Godwit, Common Greenshank, Terek Sandpiper, Curlew Sandpiper...did I miss any?!

Common Greenshank and Marsh Sandpiper are a similar pair that are often the cause of differences of opinion amongst birders! They're essentially grey and white waders with olive-grey to greenish-yellow legs.

The structural differences are sometimes obvious, sometimes less so! Here it's clear that Marsh Sandpiper is a)much smaller b) has a finer bill. What's less clear is that the legs are proportionally longer and thinner on Marsh Sandpiper than Common Greenshank. In non-breeding plumage, Marsh has a more marked head pattern (see this post), but that's much less obvious in breeding plumage. In breeding plumage, Marsh Sandpipers have beautiful, unique black arrowheads on the scapulars, greater coverts and tertials.

If you squint your eyes a bit, the marks look a bit like a flock of flying waders!

A coupe more shots of both species together.

Marsh Sandpiper is rarely mistaken for Common Greenshank; it's usually the other way around, when a Common Greenshank contrives to make itself look thinner and more elegant than usual, as here. Note the diagnostic pattern of 'pencil marks' on the tertial edges.

The two species are probably most easily confused in flight. These three are Common Greenshanks.

From below, Common Greenshank usually has a more strongly barred underwing (see this pic) to compare the two.

The upperpart pattern of both species is basically similar. Note the longer, thinner tarsus of the Marsh Sandpiper (lower pic) which means that the legs project further beyond the tail than on Common Greenshank. Other subtle differences - on Marsh, the tail is whiter and less barred, and there is more of a contrast between the pale inner wing and the dark outer wing.

Common Greenshanks calling. Both this species and Marsh sandpiper are very vocal, and learning their very different calls makes things much easier!

Of the three grey-and-white shanks, Nordmann's has the shortest leg projection of all.

They can also look ghostly pale too, with a virtually white tail and pale head. This one's tagged onto a flock of Grey Plovers, Great and Red Knot.

The underwing is clean, unbarred white.

The difference in tail and underwing patterns between Nordmann's (front) and Common Greenshanks (back) is pretty clear in this lucky photo.

The different appearance of adult and first year Nordmann's is striking! Apart from plumage differences, the bill becomes darker and the contrast between the colours less on adults as they acquire breeding plumage - a bit like Bar-tailed Godwits! Check the bill on this bird (which I believe must be an adult rather than a first summer).

When you can't see the legs (which happens quite often - Nordmann's love deep water when roosting), id comes down to plumage and other structural details. Nordmann's has a very 'square' body shape, with a flat, deep chest and pronounced 'ventral angle'. Compare this to the more slender lines of the Common Greenshank behind. The bill is decidedly thicker, especially toward the tip, more banana-shaped, and very much broader when viewed head-on. Note also the obvious and diagnostic patterns on the breeding plumage scapulars and tertials.

A videograb showing the differences in bill breadth between Nordmann's (front) and Commmon Greenshank (rear).

So, how many Nordmann's here then? My answer at the bottom of the post.

Some more NG shots.

One NG flying in to join another. If you have difficulty identifying the two godwits in the background, go to this post!

I'll end with this one. "You've been framed!"

And here's a video of a couple of birds preening.

ANSWER: I make it four - two adults and two first years (including the one that seems to be sneezing!).


Anonymous said...

Love to read your post while I am having my breakfast on holydays. Good for the body and the spirit. :)

Jose Gomez

Unknown said...

So do i Jose. Amazing thread, very usefull to distinguish these similar species.
Jesus Diez

digdeep said...

Thanks Jose and Jesus!

As you are sitting down to breakfast I am just thinking about dinner!


Tun Pin Ong said...

Hi Dave, I agree with your answer is 4. This is the most challenging comparisons between NG and Common Greenshanks I have seen. Mainly because at this time both species can be equally spotted. Need to know the spot patterns of tertials also. Tun Pin