18 Oct 2013

Great Reed Warbler & Clamorous Reed Warbler - Alba Marsh (Bahrain)

Whilst ringing at Alba Marsh (Bahrain) in the early morning of last weekend we caught four Great Reed Warblers Acrocephalus arundinaceus and a single Clamorous Reed Warbler Acrocephalus stentoreus. We caught a Clamorous Reed Warbler and a Great Reed Warbler in the same net on the same net round allowing me to take a few photographs of both species in the hand together, something that has probably not happened too often. The Clamorous Reed Warbler is mainly sedentary, although some perform short distance migrations, and the Great Reed Warbler is a long-distance migrant throughout its range. The Clamorous Reed Warbler is largely a breeding resident in Arabia with the only positively identified race occurring in the Eastern Province of Saudi Arabia as Bahrain is A. s. brunnescens which has a longer primary projection and shorter thicker bill than A. s. stentoreus making it look more like a Great Reed Warbler than many people think. We do trap birds on passage in autumn with much narrower and longer bills with shorter wings, such as the one shown below. These birds may be from the northern form A. s. stentoreus? Although currently this subspecies is only recorded as occurring in Egypt, including Sinai and Levant. They are darker/warmer and more buff coloured over most of the under-parts with a very restricted whitish area on the mid-belly, throat and chin, which is sometimes absent. Breeding birds in the region prefer phragmites reed beds rather than mangroves which is their preferred habitat in the United Arab Emirates.
Great Reed Warbler (left) & Clamorous Reed Warbler (right)
Clamorous Reed Warbler (left) & Great Reed Warbler (right)
Clamorous Reed Warbler
Great Reed Warbler
Great Reed Warbler

Above are a few photographs of both Great Reed Warbler and Clamorous Reed Warbler with side by side birds in a couple. All photographs were taken in Bahrain in October 2013. A good way to identify the two species are the wing shape and primary length with Clamorous Reed Warbler A. s. brunnescens having a short primary projection about two thirds the tertial length (half the tertial length on A. s. stentoreus) and Great Reed Warbler A. a. arundinaceus having a longer primary projection as long as the exposed tertail length. The longest primary is normally p3 for Great Reed Warbler and P3/4 for Clamorous Reed Warbler.

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