Warblers of JEO - Part 3

Week 35, 29 August 2014 - Jahra East Outfall

And so the Warblers continued to show themselves for a few hours after sunrise, whilst I continued to 'leak' profusely in the unusually humid conditions.

This post continues with 'Acro' Warblers, but the smaller and quite often (at least at this time of the year) the more challenging to ID.

We have the nominate Eurasian Reed Warbler (Acrocephalus scirpaceus) as well as the race Caspian Reed Warbler (Acrocephalus scirpaceus fuscus) together with Marsh Warbler ((Acrocephalus palustris). According to Peter Kennerley, at this time of year it is very difficult to separate the nominate Eurasian from Caspian as they are not as warmly toned as European birds although the location of Kuwait would suggest fuscus. Also, you have to consider that the effects of light, camera settings and even processing can subtly affect colour - so to be 'safe' it is better to leave them as Eurasian Reed. But, to be really sure, the best way to identify is netting and measuring the different species.

The images taken of these two species are all young (1st year) birds, so appear brighter/warmer than they would by the time they reach their African wintering grounds. Bear in mind again that light conditions affect the colour tones and differences are subtle. So, even with the luxury of time and using static images, identification is not so straight forward; as you can see for yourself below.

The Eurasian Reed is an Old World Warbler that breeds across Europe into temperate western Asia, as well as Kuwait. It is migratory and winters in sub-Saharan Africa. It is a monogamous species found almost exclusively in reed beds. It is similar in appearance to the Great Reed Warbler, but is obviously much smaller with a long slimmer bill and with a less prominent supercilium.

Eurasian Reed Warbler (Acrocephalus scirpaceus), showing a long slender bill

Eurasian Reed Warbler (Acrocephalus scirpaceus)

Eurasian Reed Warbler (Acrocephalus scirpaceus)

Eurasian Reed Warbler (Acrocephalus scirpaceus)

The Marsh Warbler (Acrocephalus palustris) is also an Old World Warbler with the similar breeding distribution as Eurasian Reed, but Marsh winters in south east Africa in dry well-vegetated areas. It is an excellent mimic and is notable for incorporating striking imitations of a wide variety of other birds into its song (31 European and 45 African species have been recorded in its repertoire). It is insectivorous and can easily be confused with several close relatives such as Eurasian Reed. However, the Marsh tends to avoid the stands of pure reed habitat, which are the Eurasian Reeds favoured habitat. Marsh is generally more olive green-brown in colour and so appears 'colder' in colour than Eurasian. Marsh in these images shows a substantial primary projection and a slightly more robust bill structure.

Marsh Warbler (Acrocephalus palustris)

Marsh Warbler (Acrocephalus palustris)

Marsh Warbler (Acrocephalus palustris)

Marsh Warbler (Acrocephalus palustris)

Marsh Warbler (Acrocephalus palustris)