Feather wear and moult in Waders: part 3 - Juvenile to 1st winter

A long time ago now I did a couple of blogs on moult in waders. Part 1 dealt with the basics of wear and moult, and looked at this process in an adult Curlew Sandpiper.

Part 2 looked at juveniles. It included the comment: " By this time, the bird is ready to undergo its first moult - into '1st winter plumage'. But that will have to wait for another post!" Well, it's been a long wait, but I realize that I did do some more pictures showing the progression from juvenile to first winter plumage which I never published, so here they are - not the complete set...watch this space (but don't hold your breath!)











Animated version here.

Up to this point the bird is still in complete juvenile plumage; the differences in appearance can be explained by the gradual wearing away of pale feather edges, which makes the bird's overall appearance plainer and darker.















In this series of pictures, two processes are going on. Wear is still occurring to the old juvenile feathers, making them duller and the patterning on them less distinct. At the same time, these old feathers are gradually being moulted or replaced by new, fresh non-breeding plumage feathers. On Curlew Sandpiper, these are generally plain and grey.The head and body feathers (including the mantle, scapulars and underparts) are completely replaced, and a variable number of wing feathers are as well.

Some of the changes are rather subtle, and might be more easily seen in the animated version here.

By November, first-winter birds look very similar to adults in non-breeding plumage (I haven't completed the sequence yet!), but they can usually be aged by the presence of a few old juvenile feathers (coverts) which retain their distinctive pattern, albeit much faded. Even where juvenile feathers lack distinctive patterning, they can often be differentiated from adult non-breeding feathers by their more ragged, heavily worn appearance. Moult proceeds assymetrically, so it's always advisable to get a good look at both sides of a bird as often, the 'give-away' juvenile feather may only be present on one wing.

Peninsular Malaysia 500 Club update

Choy Wai Mun has been rocketing up the charts lately with the addition of three lifers - Pied Imperial Pigeon, Java Sparrow and Mountain Scops-owl (can't believe you hadn't seen those already Mun ;)!), so he leapfrogs Carol.

So - any other updates from 500 Club members out there, or any potential new members??? Chin Hock? Dennis? Mike Chong? Yang Chong? Kim Chye?... there must be others...

...Noted James! Any more takers?

18th September 2010: Ipoh, Perak

I finally managed to get a couple of hours birding in on my drive back from KL to Penang yesterday.

I had two goals. One was to try look for nests of mystery swiftlets Kim Chye, Connie and I caught while doing the whistling-thrush project field work in May 2009.













































In May 2009, we caught a number of these birds in nets we had set up to catch whistling-thrushes in caves. They are very dark - the rump is blackish and concolourous with the rest of the upperparts, and the underparts are dark brown. The extent of tarsal feathering and measurements all indicate that these birds are most likely Mossy-nest Swiftlets Aerodramus salangana, a species which breeds in West Sumatra and Borneo but has yet to be recorded in the Peninsula. The nest is, as the name suggests, made of mosses and other vegetable matter, and is usually sited on a ledge in a cave, since the saliva is not sticky enough to attach the nest to the roof of a cave. For an idea of what the nest site looks like, have a look at this pic.

Anyway, frustration - no sign of either swiftlets or nests. Despite my own personal blank, the birds continue to be seen regularly, so I am quite sure they are breeding somewhere in the Ipoh area. So - Ipoh birders - your mission, should you choose to accept it - is to track down this potential new breeding species for the Peninsula! In the field they should be easily distinguishable from the typical Germain's Swiftlets by their all dark rump and dusky underparts (so they may appear all black).

My other goal was to check up on the Blue Whistling-thrushes we colour-banded back in May 2009. I have been busy over the last month writing up the final report on the project, so I've been thinking a lot about these birds lately!



It was good to see one of our colour-banded males and his mate busily feeding young. We sexed him on the basis of his brighter, richer plumage colours and more extensive metallic spangling compared to his mate.





I found that he was regularly returning to the same spot to collect... fish for his offspring! Looks like I need to re-edit that report to add another food item!







Serving up sushi!



And here's the lucky recipient!

I got a lifer today - not a bird, but a dragon!





What a beauty! This is Camacinia gigantea, which looks like several much commoner Neurothemis species but is much bigger. Apparently it's quite rare.



There were also some Java Sparrows about. Before I got married (in fact, as a condition for getting married!), my wife-to-be insisted that I show her a Puffin. I had to take her all the way to Anglesey in Wales, UK, to meet this condition. Just in case there are any other poor fellows out there in a similar predicament, and short of cash, you could try taking her to Ipoh and showing her a Java Sparrow...



...she might just be fooled! Thanks to George Diko for permission to use his great Puffin pic. More of George's pics can be seen here































































Finally, I had the good fortune to photograph this roosting Large-tailed Nightjar. From the size of the whitish tail tips, comparing them with this pic, I would say that this bird is a female.



Here you can see that the middle claw is strangely curved and has what appears to be a comb along one side. This is not a deformity, but a special adaptation possessed by some birds, such as nightjars, herons and some owls. It's known as a pectinate claw, and is thought to be used to help with preening.


.

Some old shots

I just had chance to download some pictures from my digiscoping camera, so here are some random shots from last month.




This Paddyfield Pipit was my only source of amusement during several hours in the hide in the hot sun while waiting for waders to arrive at a high tide roost on 15 August (they didn't!).

It was in the process of moulting from juvenile into first non-breeding plumage. The inner three greater coverts and all visible median coverts are adult-type feathers, while the outer greater coverts are old juvenile feathers (compare with this pic). The body moult is already more or less complete. The bill is typically rather 'weak' for a large pipit.






















In fresh plumage the entire underparts are a fairly uniform peachy-buff.

























Some more shots from the 18 August trip to Sungai Sedim

Interesting Waterbirds Part 2

The stakes are considerably higher in assessing the identification of Ang's mystery tern. After all, possible contenders include River Tern, which would be a first for the country, and Chinese Crested Tern, one of the world's rarest birds, for which there are no certain records away from the breeding area for close to a century!

Helpfully, Ang captured two other terns, which we can identify, in the same pictures - a Gull-billed (right) and a Little (left). Even allowing for the fact that the mystery tern is not on the same plane as the other two, we can confidently say that it is about the size of the Gull-billed Tern, which means that it is too big to be a River Tern.

Going back to first principles - eliminating the default common species - the only large terns which commonly occur on the West coast of Peninsular Malaysia are Gull-billed, Great Crested and Caspian Terns.

None of these should show a bill pattern like the bird in the photos, so does the bird fit with Chinese Crested Tern?

Close inspection of the photo, even though it is blurred, reveals that the yellow colouration appears to be limited to the lower mandible, rather than both, which should be the case with Chinese Crested. Futhermore, the head shows no hint of a shaggy crest, but is smoothly rounded in shape, with the black markings limited to an isolated block on the ear coverts. All of these are wrong for Chinese Crested Tern.

So, back to our default species again! In fact, the bird looks in all aspects except the bill like a 1st winter Gull-billed Tern. A brief scan for Gull-billed Tern images on the web turns up this picture (scroll down) and this one. Mystery solved! It seems 1st winter Gull-billed Terns can show a yellow base to the lower mandible, something I didn't realize before!

Interesting waterbirds Part 1

Thanks to Alfred, Jason, Tsu Shi and Tun Pin for your comments.

When faced with a potential rarity, the first step is always to eliminate the 'default' common species.

In the case of the small calidrid, the default species is Curlew Sandpiper. So, is it one, and if not, why not?

Ang picked it out at first due to the shorter-than-usual bill. This in itself is not enough to rule out Curlew Sandpiper, as some males can show shortish bills, but it does at least put us on the alert. Are there any other features which are 'odd' for Curlew Sandpiper?

Well, the overall body shape is rather 'dumpy' for a start. Curlew Sands tend to look elegant and slender, a combination of longish legs and a quite attenuated 'back end'. This bird has a short primary projection (very little black visible beyond the tertials), and the wingtip appears to fall just beyond the tail tip. Again, this is suggestive rather than diagnostic of Dunlin . Most Curlew Sandpipers show a longer primary projection beyond the tertials and the wingtip tends to fall well beyond the tail, but this isn't always the case (as, for example, with this bird).

Unfortunatetly the bird is wading in deep water, which doesn't help us to asses the leg length easily. However, the visible tibia (between the body feathers and the leg joint) is very short, and in the shot I posted yesterday, Ang has managed to capture one leg raised momentarily above the water, revealing a very short tarsus. This is the first solid indication that this cannot be a Curlew Sandpiper.

Going back to the bill and head, the bill curvature is not quite even - not as kinked as a Broad-billed Sandpiper - but not as smooth a curve as is typically the case with Curlew Sandpiper, and this is also a feature of many Dunlin. The face pattern is rather bland, with the supercilium virtually disappearing behind the eye. Curlew Sandpiper should show a much more prominent supercilium behind the eye, whereas non-breeding plumaged Dunlin is typically bland-faced. Finally, Dunlin tends to show a high forehead and rather domed crown (see the pictures here to see what I mean).

So we can give a number of reasons why it isn't a Curlew Sandpiper and why it IS a Dunlin:

1. Very short tibia and tarsus
2. Dumpy body and short primary projection
3. Bland face and indistinct supercilium behind the eye
4. Slightly kinked bill
5. High forehead and domed headshape

Aging this bird is not easy from the picture we have, but the lesser coverts (visible just below the scapulars) seem to have diffuse grey-brown edges and the wing coverts as a whole do not appear in neat rows. Both of these features suggest an adult. This is confirmed by the presence of black flecks on the ventral area, which must be the last vestiges of breeding plumage.

There are lots of races of Dunlin worldwide - up to ten depending on which taxonomy is followed. There's a helpful map showing the breeding ranges of the various races here, from which I conclude that five: actites, kistchinski, sakhalina, articola and pacifica, could potentially occur. Which one this is I wouldn't like to speculate - perhaps someone with more experience of Asian Dunlins can help.

Dunlin is a genuine rarity in Malaysia, with probably fewer than 12 records in the whole country. So congratulations to Ang on a sharp piece of spotting!






















Another picture of the Dunlin (below) with a first winter Curlew Sandpiper (above) taken by Ang on the same day, which illustrates the structural and plumage differences between the two species very nicely.

Some interesting waterbirds from Kapar

Since I haven't managed to get into the field for almost a month, I've asked permission from Ang Teck Hin to post some of his recent discoveries at Kapar Power Station, Selangor, the country's prime migratory waterbird site.



The first is a small calidrid sandpiper with a shortish downward-curved bill.





The second is potentially even more interesting - the large, pale-mantled tern on the left of the picture with a mostly yellow, black-tipped bill!

Before I say what I think they are, I thought it would be interesting to hear other people's opinions!