Ron-Nature-Adventures: Shorebirds at Kapar site and their plumage terminology

It has been almost 10 months since my last shorebirds survey trip. So I am very glad to be back in action. This time I join a group of 'new' birders to this shoreline. Naturally at this time of the year, the newly arrived birds are still having their colourful breeding plumage and they didn't disappoint us.

Tibetan Sand Plover with a Red-necked Stint

Anarhynchus atrifrons & Calidris ruficollis

Tibetan Sand Plover

Anarhynchus atrifrons

Apparently there are two types of 'Lesser Sand Plovers' which have been described as two distinct species of their own. One of them is the above. Majority of the waders seen here were from this group/species (A.atrifrons).

Tibetan Sand Plover

Anarhynchus atrifrons

Some of them are still very much in their breeding plumage.

The other one which Dave Bakewell described as "having shorter, more blunt-tipped bill and slightly shorter legs. In flight, looks long-winged; white wingbar is typically less extensive than on other sand plovers" is the Siberian Sand Plover (Anarhynchus mongolus) of which is reported not being seen in Malaysia as yet ! Note: All the above Sand Plovers are Tibetan Sand Plovers and the blurry one in the foreground is actually a Broad-billed Sandpiper.

Initially I thought this Plover might fit the description of a Siberian Sand Plover but experts say nope.

Here's another one.

It appears like one of those A. mongolus race of Stegmanni.

Naturally the most attractive ones will be those with their red hot plumage and none is more prominent than the ones shown by the Curlew Sandpiper.

Curlew Sandpiper

Calidris ferruginea

Speaking of plumage, I found out a word called 'Transition Plumage' which the literature described as "the temporary feather condition when a bird is molting between its non-breeding (basic/winter) plumage and breeding (alternate/summer) plumage". During this transition process, their feathers will look like the above bird - 'patchy', 'scruffy', 'smudgy' and 'oddly patterned'. Scroll further down to learn more about their plumage terminologies.

Here are a few more photos showing the various 'transition' plumage of some Curlew Sandpiper.

It looks like having speckles of jewels on its back.

Two Curlew Sandpipers showing two different plumage profiles.

This Curlew Sandpiper as do the other birds above are most likely experiencing what is called a 'staged pre-basic moult'.

As usual, each trip would produced some 'unusual' looking shorebirds.

When I posted this photo in FB, many experts have refrained from commenting but I think it was just a Great Knot (Calidris tenoirostris).

Eventually all of them came and landed safely.

Great Knot (Calidris tenoirostris).

Ruddy Turnstone

(Arenaria interpres)

They are actually common but their numbers are only a handful here. That makes them one of those a must-see shorebirds.

Ruddy Turnstone

(Arenaria interpres)

In flight

Ruddy Turnstone

(Arenaria interpres)

In this trip, I only saw four of them.

Broad-billed Sandpiper

(Calidris falcinellus)

Here's another wader which population has probably reduced. I only saw three at this site.

We also saw these duck-liked waders 😃

Terek Sandpipers

Xenus cinerues

Their numbers are just slightly more than those of Broad-billed Sandpipers

This is probably the third largest number of waders seen at this site after the Tibetan Sand Plovers and Curlew Sandpipers.

Red-necked Stint

Calidris ruficolis

They are always at the forefront if you see them together with flock of mix waders.

Red-necked Stint

Calidris ruficolis

Red-necked Stint

Calidris ruficolis

Only a small number of them are showing their summer plumage.

Red-necked Stint

Calidris ruficolis

90% of them are already in their basic/winter plumage.

Red-necked Stint

Calidris ruficolis

Looking neat and sharp.

Here's another plover which is not easy to find although they are not uncommon.

Greater Sand Plover (Charadrius leschenaultii)

As in the case from my previous waders surveys, I have noticed that there are quite a number of juvenile birds accompanying adult birds in their long journey to their respective wintering grounds. These observations are probably in contrary to the earlier saying that adult birds will arrived earlier than the juveniles. These observations may also meant that there are likely some irregularities in the waders' breeding patterns/timing which may also indicate the effect of climate change.

Greater Sand Plover

(Charadrius leschenaultii)

Juvenile

Here comes the rest of the smaller juveniles.

Tibetan Sand Plover

Lesser Sand Plover (previous common name)

Anarhynchus atrifrons

Charadrius mongolus atrifons (previous scientific name)

Tibetan Sand Plover

Anarhynchus atrifrons

Charadrius mongolus atrifrons (previous scientific name)

Juvenile

Tibetan Sand Plover

Anarhynchus atrifrons

Charadrius mongolus atrifrons (previous scientific name)

Juvenile

Another juvenile.

Tibetan Sand Plover

Anarhynchus atrifrons

Charadrius mongolus atrifrons (previous scientific name)

To appreciate more the beauty of these shorebirds, one can dive deeper into their plumage formation. Here are a few common terminologies in the avian literature which describe the various formations. I hope I am able to show them in a pictorial form.

Pre-formative plumage according to the avian literature involves the transition of juvenile plumage to a more adult-like appearance. The above is a juvenile Tibetan Sand Plover (A.atrifrons).

According to Dave Bakewell (a local resident bird expert here), the prefix 'Pre' can't actually be used with a plumage. I think what he meant was that to describe a bird's plumage, you can use/describe them as either an 'Alternate Plumage' or a 'Basic Plumage' but not as "Pre-alternate plumage or "Pre-basic plumage". However, you can use the word 'pre' to describe the feather moulting process such as Pre-basic moult or 'Pre-alternate moult. To illustrate the above meaning, have a look at the photo below:

To describe the plumage of the bird on the left, we can't describe it as having a 'pre-basic plumage' but we can describe it as having a pre-basic moult (as per Dave Bakewell's suggestion). Anyway since some literature did mentioned / include the word 'pre' in their explanations, so the word 'pre' is included here just for my general knowledge to understand the feather transformation process.

Once the juvenile birds reached from 2cy bird/adult staged, their feathers will then transit to their pre-alternate plumage.

Pre-alternate plumage - usually occurs before breeding season whereby the feathers will eventually become their alternate plumage which is actually their breeding plumage. There is also another term which is called a partial pre-alternate plumage which involves only some partial feather replacement. Unfortunately I am not able to find any suitable or rather reliable photos to depict this moult.

Note: in Dave Bakewell's gospel, the correct term to describe the above bird should be it is undergoing a Pre-alternate moult which will eventually leads to its alternate plumage.

Also note that because these post and photos here were taken in the month of August, the above bird is actually in its alternate plumage undergoing a pre-basic moult.

Here is a Tibetan Sand Plover showing its breeding / alternate plumage.

After breeding season, the waders' feathers will then moult into a 'Pre-basic Plumage'.

Pre-basic plumage usually occurs after breeding season whereby their feathers will eventually moult into basic/winter plumage.

Note: in Dave Bakewell's gospel, the correct term to describe the above bird should be it is undergoing a Pre-basic moult which will eventually leads to its basic/winter plumage.

Here's another example.

The bird on the left is showing an 'Alternate Plumage' while the bird on the right is having a pre-basic moult which its overall plumage will eventually turn into Basic/Winter plumage.

Avian literature as well as experienced birders are mostly suggesting that most birds adopt a 'Proximal Replacement' approach in their Primary Moult process i.e from inner primary feather (P1) to outer primary feathers (P9 or P10).

An Eurasian Curlew showing some primary moult from 'proximal' to 'distal' as well.

The highlights of watching shorebirds/waders does not only confine to seeing rare birds. It is also involve finding banded birds. To me, being able to spot a banded bird is equivalent of seeing a rare bird.

A Curlew Sandpiper with a 'White-over-Yellow' VN tag.

Here is what Catherine Leung, an expert ringer from the 'East Asian-Australasian Flyway' (EAAF) group has to say about this bird:

"Curlew Sandpiper white-over-yellow VN was banded by my team at Mai Po Nature Reserve, Hong Kong on 7-Apr-2023 as adult. It was observed in Luannan, Hebei, China for 3 consecutive spring: May-2023, 2024, 2025 and reported once in Kapar, Selangor, Malaysia in Aug-23"

Coincidentally this Curlew Sandpiper was also seen at Kapar and I believe this same bird could have also visited the same area in 2024. It is probably not seen by the shorebird spotters.

Here are a few flight photos. Most of them were taken from a distance.