Clamorous Reed Warbler or Oriental Reed Warbler? (1 Viewer)

[Jane Turner]

But what about the head structure?

 

[hannu]

First of all, original bird is 1cy bird, thus it's still rather fresh plumage in October. The head structure seems to vary in these juvenile birds, especially supercilium (mostly in the front of the eye).
Also the open bill in the original case possibly bluff us to believe that the bill is thinner than in reality.

 

[Jane Turner]

I mean't the bill width/length and in particular the relative size of the eye. What we really need is a Far-eastern Orthoptera specialist! Then you would have a ruler in the photo!

 

[hannu]

I mean't the bill width/length and in particular the relative size of the eye. What we really need is a Far-eastern Orthoptera specialist! Then you would have a ruler in the photo!

I admit that this case is very difficult, because the position of bird is not optimal. Also the fact that the complete postnuptial moult of A s brunnescens takes place from September to November, causes difficulties to id bird. So perhaps also the age of the bird is also difficult to estimate.

Bill length seems to overlap in these species. Also Oriental Reed Warbler has not so heavy bill than Great Reed Warbler. So in my mind, it's almost impossible to judge dependaply the size of bill in this case.

bill to nostril:
A s brunnescens 13,2 - 15,5
A orientalis 12,9 - 14,3

One difference between brunnescens and orientalis is the amount of emargination:
A ori p(7-)8,
A s bru p(6-)7-8
Difficult to see this detail too.

Perhaps it's better to leave identify for sure! However, interesting case!

 

[Jane Turner]

Of course there is one unstreaked Acro that shows intermediate characteristics between small and large species, though its a bit of a long shot and not exactly well known!

 

[hannu]

which one ?

 

[Jane Turner]

http://www.birdlife.org/images/raw/b_acrocephalus_orinus.jpg

One record from Thailand and another from India!

 

[Jane Turner]

I don't believe that this bird is A orinus. E.g. Orinus looks clearly slimmer and longer , underparts clearly whiter and also it has paler legs.

I'm not that sure we really know what the species looks like - there being one specimen, one trapped bird and that amazing set of photos taken in the field in India of a third individual.

Its not exactly likely though. It was failed attempt at humour!

 

[hannu]

There are some details, which disturb me in your proposal: e.g. the colour of underparts and legs, the length of tertials.

 

[hannu]

more pics from A orinus
http://www.bcst.or.th/eng/news/n12.html