sábado, 5 de febrero de 2011

Leucistic Red-billed Chough in S Lleida [Chova piquirroja leucística en el sur de Lleida]

Leucistic Red-billed Chough (P.pyrrhocorax). Mas de Matxerri, Castelldans, Lleida. 4.2.2011
(© Ricard Gutiérrez)



Alerted by fellow birdwatcher Sergi Sales who had been watching the bird along the week, on the 4th of February 2011 afternoon we payed a visit to the Mas de Melons nature reserve, an steppe area in S Lleida comarque of Garrigues. When heading to the Matxerri valley of such reserve, we saw a flock of >40 Red-billed Choughs (Pyrrhocorax pyrrhocorax) which were foraging in the area. One of them, near the main group but somewhat to the edge of it, was showing the characters Sergi had told us: large milk & coffee coloured wings with otherwise regular coloured bare parts and black body. An aberrantly coloured Chough. While approaching the flock, two Red-legged Partridges (Alectoris rufa) flushed and soon afterwards the choughs followed them. Only in-flight record shots could be obtained (Emma Guinart, Ricard Gutiérrez).


Leucistic wing feathers included secondaries, greater coverts, primary coverts and outer primaries, while some innermost primaries (2-3), lesser & median coverts and alula remained normally coloured. Note that the included photos were taken in strong afternoon sunlight, thus showing very bright feathering.


Species identification was straightforward despite colour aberration since bare parts and structure were not affected, bird e.g. showing largest outer three primaries of almost equal-length and typical bill colour. Besides, voice was that of Red-billed Chough (Madge & Burn 1994). Leucism may be the commonest of colour aberrations since it does not compromise birds' eyesight because eyes (and bareparts even some parts of plumage) remain normally coloured (van Grouw 2006). As far as we know, this is the 1st reported leucistic Chough at least in NE Spain.




Leucistic Red-billed Chough (P.pyrrhocorax) following nine 'normal' birds . Mas de Matxerri, Castelldans, Lleida. 4.2.2011
(© Ricard Gutiérrez)



Resumen. Chova piquirroja leucística en el sur de Lleida.
El 4.2.2011 y después de haber sido alertados por Sergi Sales que había visto el ave durante la semana, se pudo observar y fotografiar un ejemplar leucístico de chova piquirroja (P.pyrrhocorax) en Mas de Matxerri, Castelladans, Lleida (E.Guinart, R.Gutiérrez). El ave presentaba partes decoloradas en las alas: secundarias, cobertoras mayores, cobertoras primarias y primarias externas, mientras que las primarias internas, alula y cobertoras menores y medianas eran normales. No se conocen casos previos, al menos en el NE Ibérico, de chovas leucísticas.


Resum. Gralla de bec vermell leucística al sud de Lleida. El 4.2.2011 i després d'haver estat alertats per Sergi Sales que havia vist l'ocell durant la setmana, es va poder observar i fotografiar un exemplar leucístic de gralla de bec vermell (P.pyrrhocorax) al Mas de Matxerri, Castelladans, Lleida (E.Guinart, R.Gutiérrez). L'ocell presentava parts decolorades a les ales: secundàries, cobertores majors, cobertores primàries i primàries externes, mentre que les primàries internes, alula i cobertores menors i mitjanes eren normals. No es coneixen casos previs, al menys en el NE Ibèric, de gralles de bec vermell leucístiques.


References


  • van Groow, H. 2006. Not every white bird is an albino: sense and nonsense about colour aberrations in birds. Dutch Birding 28: 79-89
  • Madge, S. & Burn, H. 1994. Identification of jackdaws and choughs. British Birds 89: 99-105



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