Wednesday, October 14, 2009

A Tale of Two Redshanks

Going back to that odd Common Redshank I photographed in Singapore recently, Prof Bill Hale has helped me to age the bird as a first winter.

The ultra-close views which Sungei Buloh allows of Common Redshanks reveal some interesting variations in plumage.

These are two adults in non-breeding plumage, yet the pattern of the non-breeding coverts is quite distinctly different, as shown by the two isolated median coverts. The upper bird has rather plain brown coverts, with a thin whitish fringe and barely discernible subterminal marks. The lower individual has rather obvious blackish subterminal notches on most median and greater coverts.

Here's a juvenile in what I would call 'typical' plumage. The coverts are dark brown with warm buff edges, and median and greater coverts have dark notches.

Now back to the puzzling bird!

The lesser coverts and uppermost tertial are 'typically patterned' juvenile feathers, proving that this is a bird hatched this year. The scapulars are all non-breeding feathers, showing that it has undergone its first head and body moult into '1st non-breeding plumage'.

These inner greater and median coverts also seem to be '1st winter' feathers, being similar in pattern to the lower of the two adults above.

And finally, what about these feathers?? Presumably, they are juvenile coverts, but quite significantly different from the pattern of those on the juvenile above.

So, I wonder if these represent merely individual variation, or whether they might be indicative of different populations (present sub-species). Something for the wader-banders at SBWR to look into!

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