Young Warbler as an ID-challenge in southern Brandenburg in Germany

SumpfrohrsängerIn the beginning of August I shot the image of a drab warbler near a pond in southern Brandenburg. I did not realize the bird at that moment, as the whole willow bush in a otherwise highly agricultural land was quite busy with migrating birds, e.g. Sedge Warbler (Acrocephalus schoenobaenus) well. I think, I remember that “Marsh Warbler” was my first thinking? The slender appearance on one of the images would be a hint. But he greyish tinged legs, the shape and colour of the bill and especially the head pattern made me think of a Sylvia-Warbler. The brownish cap could be some pollution/ pollen, yes. But I thought this not very useful in August.  What really irritated me were the colour and the contrast in the tertial fringes, which was the reason I had the impression that the bird looks a hybrid between a Blackcap (Sylvia atricapilla) and a Common Whitethroat (Sylvia communis). Looking at the images with 2 month in between, I was more in the direction of thinking of a young Blackcap due to the whitish eyering and the shape of the bill. But the extent of brown on the cap was very restricted. I was unsure again, as the bird looked like a hybrid between a Blackcap and a Common Whitethroat.

I made the observation a theme in www.birdforum.net. The first response was: “…..why not a Marsh Warbler (Acrocephalus palustris)? Such greyish tinged legs are very rare in this species, but apart from this it looks good for this species. The browhnish cap can be some pollution/ pollen ? Colours, distinct tertial fringes, head pattern with short Hippolais like bill is better for Marsh than for Reed Warbler, but if someone can prove this is a Reed, I would be happy to learn, as I am very interested in this ID-challenge and …..”.

Otherwise and after a second look, the colours were just ok for the palest, less rufous, coldest Eurasian Reed-Warbler (Acrocephalus scirpaceus) that can occur.

After a fourth look, I had another argument. On one of the images, there seemed to be some uppertail coverts visible. On the few cold, less rufous Reed Warbler the expert had seen, the rump was still clearly warmer than the back. This seems to be not the case in this bird.

The author pointed out, that on many Reed Warblers with slightly less warm upperparts the rump shines contrastingly, as it has a different colour compared to the tertial fringes. The impression might be seen in this bird. On Marsh Warblers, the rump is often nearly or exactly the same colour, or you can find warmer (orange) tones somewhere on the wings or tertial fringes. As this bird seems to have the same colours to the uppertail coverts and the back/wing, the author was more or less convinced the bird beeing a Marsh Warbler.

The author got support by another user, who surely could not see a Sylvia-warbler due to the head shape and tail shape and pattern.

With this, I was convinced to have photographed a young Marsh Warbler.

To cope with the growing demand for top shots of the rarer species of the Palearctic Bird-Lens is keen to enrich the range of pictures of birds you can find in the western Palearctic. Trips to common and to remote places to capture images not only of rare birds of western Palearctic were very successful. The nice image of the blog is only a first impression, what you will find in the gallery in the “Picture Shop” very soon. Just give bird-lens.com a message, if bird-lens.com could serve you with an image needed before the new pictures are online.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.