Visiting a winter wader roost on near enough midsummer's day may seem the height of folly, but the large number of waders recorded at Kapar in late May made me wonder how many birds were actually not actively migrating, but were choosing to oversummer at Kapar.
I arrived at the site at about 2pm, and the ashponds were completely devoid of birds - a barren wasteland. Within an hour though, the first Eurasian Curlews began to drift in, and, by 5 o'clock, there were over 3,500 waders (and 17 species) present! Unfortunately from a photographic point of view, the majority did not roost at the usual site, but chose instead to feed not far from the inflow pipe. Here's a selection.
All the birds I could age were in '1st summer' plumage. Birds which hatched last breeding season would have undergone a body moult into 1st winter plumage last autumn, and then another body moult into '1st summer' plumage. This means that most of their flight feathers would be around a year old, and extremely worn and bleached. In theory, these feathers are not replaced till the second autumn of the bird's life, when it moults into its second winter/adult winter plumage.
However, what was interesting was that most birds had already begun to moult their primaries.
This Bar-tailed Godwit has just begun its primary moult; the inner two are full grown, and the third is still growing. The primary covert moult is happening in parallel. Note how much paler and more bleached the old feathers are.
Another Bar-tailed Godwit in the same flock has almost completed its primary moult (only the longest outermost two are still unmoulted), though it doesn't seem to have started secondary moult yet.
This Whimbrel shows clearly the difference in colour between the outer unmoulted primaries and primary coverts, and the fresh inner ones.
Another interesting variation on view was the range of barring on the underwings of Whimbrels. Unbarred white underwing coverts are supposedly a feature of the race 'phaeopus', while barred underwing coverts should indicate 'variegatus'. However, this photo shows that there may be some intergrades.
Here's a composite of the three birds with raised wings in the photo above, which nicely illustrates the gradation in degree of underwing covert barring.
Another noteworthy observation was the count of Ruddy Turnstones - 42 being double my previous highest count in Malaysia. Some of these birds seemed to be in pristine breeding plumage, which made me wonder whether some were already on their southward journey, possibly failed breeders??
Overall totals were:
Grey Plover 50
Pacific Golden Plover 3
Lesser Sand Plover 300
Greater Sand Plover 180
Eurasian Curlew 650
Bar-tailed Godwit 400
Common Redshank 450
Common Greenshank 36
Terek Sandpiper 50
Ruddy Turnstone 42
Red Knot 15
Great Knot 200
Red-necked Stint 100
Curlew Sandpiper 160
Broad-billed Sandpiper 1
Grey Heron 25
Purple Heron 2
Little Egret 75
Great Egret 1
Little Tern 8
Gull-billed Tern 15
As I was leaving the site I had one more pleasant surprise - the sight of a leucistic Javan Myna feeding among some cows.