Thursday, May 20, 2010

Isabelline Warbler (Western Olivaceous Warbler)

A singing Isabelline Warbler (Hippolais opaca) doubtless was the highlight of today's trip around Faro. We found the bird near the hide at the Quinta do Lago Golf-course this morning, where it has been singing out of the dense crowns of the Umbrella-Pines at this place. After a while we also got views of this bird climbing through the dense vegetation and sitting in the open every now and then just for a moment. The bird lacked any yellowish or greenish color-tone of the possible confusion-species Melodius Warbler (Hippolais polyglotta). The song also differs - it resembles a bit a Reed Warbler (Acrocephalus scirpaceus) which does not sing out of the crowns of Pine-Trees and shows some reddish-brown in the plumage.

João Tiago Rocha Tavares managed to get the following photos of the bird:

A link to an external site on the ID of Melodius Warbler versus Olivaceous, including sound files, is here.

This his apparently a bird on spring migration - they are very late migrants.
There is only one known breeding-record for Portugal over the last years (Alentejo). This bird is rare - but also easy to overlook, and ID in the field is very difficult, especially when the birds don't sing (autumn-migration).

Links about the splits of Hippolais-Warblers are here and here.

This is also interesting.


  1. I was on this tour. To identify the bird, by call initially was most impressive as the location is noisy, very close to a lagoon with much bird noise from young ducks/coots/moorhens etc.
    I then saw the bird very clearly in full sun for 10-15 seconds-certainly long enough to know that without Georg I would never had identified the bird from my Collins Guide as it is most unremarkable! The call however was precisely the same as played by Georg on his very clever little MP3 player. Our group (I am embarrassed to say) were probably more impressed by seeing the beautifully marked nearby black headed weavers and the overhead black kite.

  2. Thank you for your comment. I also remember a clear sight on the head of bird - which was the head of a "Hippolais"-Warbler and not of Reed-Warbler. Higher, more of a "crest", bill not as long. There has been still a discussion about the bird, and based on the photos alone, I can understand this. However, moulting, light conditions (photo) and individual variation have to be considered. Best regards.

  3. There may be discussion aboiut the bird-but I saw the bird very clearly, and heard it singing for fully 5 minutes exactly the same call as on Georg's player. The bird was 100% correctly identified.

  4. I have been talking with myself about this bird for a long time. Especially the undertail proportions (rectrices and coverts) seemed weird relative to what I would expect. But searching the web for pics, I found that western olicaceous (isabelline) warbler can have apparent slight graduation on rectrices (regardless of moult) and actually have longish lower flank and undertail feathers. The width of the bill was not easy to see i the photographs, but it is visible at close inspection (believe me, I have watched it closely, and pics from reed warblers are certainly thinner). Put it together with what I have seen with binoculars and heard and you get a WOW: western olivaceous warbler.