Mostrando entradas de julio, 2018

Apparently 'brown' Reed Warbler in Alicante [Aparente carricero común 'brown' en Alicante]

© Juanma Ferreira En castellano más abajo On 21 July 2018 a 'pale' Reed Warbler ( Acrocephalus scirpaceus) aged EURING 3 (born in 2018) was trapped and ringed at Algar river, Alicante (Toni Zaragozí, Juanma Ferreira, Paco Galindo). Its identification was straightforward thanks to biometrics and its structure and general shape. However, the bird was extremely pale, diluted, compared to a regular Reed Warbler (see enclosed photos). The bird presented a colour aberration in which apparently the pigments responsable for black coloration (eumelanins) were missing. Brown pigments were present (originated by phaeomelanins) and the regular eye colour discarded an albino, which would also present a full white coloration.  This pale bird would apparently be showing a 'brown' aberration. This colour variation is caused by a qualitative reduction of eumelanin. The whole amount of pigmentation does not change but 'black' is missing. A leucistic b