Ageing Greenshanks: Teluk Air Tawar, Penang, 28 Jan 2013

On my way back today to try to get a better count for the Asian Waterbird Census, I stopped at the mouth of the Sg Abdul.

Bagan Belat low tide_280113_IMG_0167

I love the moonlight on the mudflats.

Bagan Belat low tide_280113_IMG_0277

The same view a couple of hours later.

Common Greenshank_280113_IMG_0264

Common Greenshank_280113_IMG_0233'Common Greenshank_280113_IMG_0233A small flock of Common Greenshanks fed very close by, catching the light as the sun rose.Common Greenshank_280113_IMG_0266

I find Common Greenshanks among the most  difficult waders to age at this time of year, as their plumage is so variable. However, adults should have fresher primaries than 1st years, having undergone a full moult last autumn (whereas juveniles do not moult flight feathers in their first autumn.)

Common Greenshank wing_280113_IMG_0216 Common Greenshank wing_280113_IMG_0264 Common Greenshank wing_280113_IMG_0207

These adults all show fresh, evenly-rounded, blackish primary tips. The fresh and old tertials both show the many-notched pattern of adult plumage.

Common Greenshank wing_280113_IMG_0237 Common Greenshank wing_280113_IMG_0233These two first winter birds show worn, brown primary tips (retained juvenile feathers), and the fresh tertials are ‘weakly’ patterned, lacking the well-defined ‘pencil mark’ notches of adults. The base colour of the tail feathers also looks browner than the crisp white of the adults. Another difference evident in the pictures above is that the primaries on juv/1st winters extend only marginally beyond the tail tip, whereas on adults, they clearly project beyond. However, this difference may not be apparent when juveniles have fresh primaries, as here.

Using these features, it is possible to age the bird in the topmost frame above as an adult, and the second one as a first winter.

Common Greenshank_280113_IMG_4078An adult (front) and 1st winter (rear). Though the first winter looks obviously darker and browner than the adult, this is not a good ageing feature in itself. Some adults can look brown and dark, while some first winters look grey (refer to the top two pics in this series!)


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