15 March 2012

Savi’s Warbler – Alba Marsh (Bahrain)

Whilst ringing at Alba Marsh on 9th March we caught a strange bird, for us at least. It was obviously not a Caspian Reed warbler as it was too big but was much too small for Clamorous Reed Warbler of Great Reed Warbler. Initial thoughts than turned to Basra Reed Warbler but things did not look right for this species even though I had never seen one and Brendan had only seen a single bird in the hand last year. The bill length did not look long enough for Basra Reed Warbler and the under-parts colour was not white enough either. This combined with the leg colour being reddish rather than grey and the tail shape and wing shape appearing wrong seemed to eliminate the species. It is amazing how different birds look in the hand than they do in the field. We checked details in Svennson’s ringing guide but the wing measurements and details did not fit for any of the Acrocephalus warblers. As a result we started looking at the Locustella warblers as the bird had very long under-tail coverts. From this point onwards it became clear the bird was a Savi’s Warbler which is a good bird and is classed as a vagrant for Bahrain. I had heard a singing Savi’s Warbler at the very same spot where this bird was trapped the week before (see previous weeks ringing post) and mentioned it to Howard King, who was at the site, and Brendan but did not realise its vagrant status. The sub-species of Savi’s Warbler we get in the area is fusca which is more olive brown with paler under-parts and slightly different to the European lusciniodes. Fusca breeds in Turkey & Jordon to central Asia including north & south Kazakhstan, Turkmenistan, north-east Iran and probably north-west Afghanistan and winters in north-east Africa principally in Sudan & Ethiopia. The Savi’s Warbler has bred in the Eastern Province of Saudi Arabia and has been suspected to breed in Kuwait (G. Gregory 2005).