[Richard Klim]

Mátrai, Bakonyi, Gyurácz, Hoffmann, Raijmakers, Neto & Mátics (in press). Do the European Great Reed Warblers (Acrocephalus arundinaceus) reach South Africa during wintering? J Ornithol. [abstract]

[jacana]

Lots of maybes and mights in that abstract...

[MJB]

Originally Posted by Richard Klim

Mátrai, Bakonyi, Gyurácz, Hoffmann, Raijmakers, Neto & Mátics (in press). Do the European Great Reed Warblers (Acrocephalus arundinaceus) reach South Africa during wintering? J Ornithol. [abstract]

A useful baseline work to which future studies of the poorly-studied Middle East populations (eg Syrian wetlands if that political crisis can be resolved) can refer.
MJB

[Richard Klim]

Hansson, Tarka, Dawson & Horsburgh 2012. Hybridization but no evidence for backcrossing and introgression in a sympatric population of Great Reed Warblers and Clamorous Reed Warblers. PLoS ONE 7(2): e31667. [pdf]

[MJB]

Originally Posted by Richard Klim

Hansson, Tarka, Dawson & Horsburgh 2012. Hybridization but no evidence for backcrossing and introgression in a sympatric population of Great Reed Warblers and Clamorous Reed Warblers. PLoS ONE 7(2): e31667. [pdf]

Richard,
An intriguing paper! Now, I wonder, first, what might transpire between sympatric populations of GRW (any taxon) and ClamorousRW taxon A.s. stentoreus, and second, where GRW does not occur, across the extent of the CRW stentoreus/brunnescens shared distribution (cline/stabilised hybrid zone - take your pick)?
MJB

[Richard Klim]

Ion, Bolboaca, Ciorpac, Stefan & Gorgan (in press). A Great Reed Warbler × Reed Warbler hybrid (Acrocephalus arundinaceus × Acrocephalus scirpaceus) in northeastern Romania. J Ornithol. [abstract]

[MJB]

Originally Posted by Richard Klim

Ion, Bolboaca, Ciorpac, Stefan & Gorgan (in press). A Great Reed Warbler × Reed Warbler hybrid (Acrocephalus arundinaceus × Acrocephalus scirpaceus) in northeastern Romania. J Ornithol. [abstract]

Richard,
I've seen very occasionally around the Neusiedlersee reedbeds (which I've visited many times, the next in May) and once at Hortobagy fishponds intermediate-sized 'reed' warblers. Only one I heard sing - it sounded like a GRW on a bad day. After a few days, a full-size GRW seemed to have taken over that territory.

Now to speculate. If any of the anomalous birds were hybrids, then I suggest that males would be outcompeted by both species on song when trying to attract females, outcompeted physically by GRW males for territory, outnumbered hugely by males of both species (territory size can be astonishingly small in prime habitat) and therefore unlikely to add successfully to the gene pool. That's begging the question as to whether hybrids are first/second generation fertile, of course.
MJB

[Richard Klim]

Originally Posted by MJB

Only one I heard sing - it sounded like a GRW on a bad day.

Mike, the 'song' of Great Reed Warbler is hardly musical on a good day!

[MJB]

Originally Posted by Richard Klim

Mike, the 'song' of Great Reed Warbler is hardly musical on a good day!

Richard,
Don't I feed you the best lines!
MJB
PS The odd call perhaps is better described as an inauthentic 'Gurk!'.