viernes, 11 de marzo de 2011

A travelling Pied Crow [Un Corvus albus viajero]

© Léa Beligné, Tarragona, 4.3.2011



On 4.3.2011 Léa Beligné, a SEO/BirdLife volunteer from Riet Vell reserve, Delta de l’Ebre, visited Tarragona city and found a large white and black raven close to the roman amphiteater.

The bird could be approached and some photos were taken, two of which are enclosed here. The bird was in good shape and was carrying a green PVC ring with letters ‘CY’ on its left leg. Once shown these pictures to Josep Tantull, Roser Solé and RG at Riet Vell on 9.3 the bird was immediately identified as a Pied Crow (Corvus albus), a species that has been recorded before in other places of Spain.

Being close to the Tarragona harbour, the possibility of a ship-assistance arrival was a possibility to take into account, despite the ‘odd’ pvc ring that did not appear in any ringing webpage neither European or African. Contact was quickly made with Albert Cama, the Tarragona birdwatcher, who lives close to the sighting area. That very morning the loud and harsh call of the Pied Crow was heard through our mobile phones: the bird was still at Tarragona city that week. A later attempt to see the bird in the afternoon failed but contact with the wardens of the amphiteater demonstrated that the bird was present in the area from 2.3.2011.


A further research through the internet brought to light one particular photo on flickr of two Pied Crows caged in the collection of the Barcelona zoo, c.100 km to the North. The page of the Barcelona zoo with the file of the species clearly showed the same ring with ‘CY’ letters in one of the two birds kept there. On 10.3 it was confirmed that the Tarragona Pied Crow came indeed from the Barcelona Zoo from where one bird had escaped ten days ago.


© Léa Beligné, Tarragona, 4.3.2011


Pied Crow is an Afrotropical species that has been accidentally reported in the Western Palearctic (Lybia, Algeria and Egypt) most of the times being considered as escape but with some reliable records in E Africa where one pair has bred in the Western Sahara (Batty 2010, Dutch Birding 32:329-332). The current Spanish records have either been considered escapes or ship-assisted birds. The capability of ship-assistance by this species is clearly demonstrated by an offshore sighting on board a fishing vessel 122 nautic miles from Sahara and 125 S of Gran Canaria island on 26.11.2002 (Martínez & Baroné 2006, Alauda 74(2): 275-276). This proven case of 100 km-long distance travelling o a proven escaped bird demonstrates how powerful, despite a long-time cage staying, this species can be and that not all escapes need to come either by boat or from a nearby collection.


Acknowledgements: Léa Beligné , Albert Cama, Josep Tantull, Roser Solé and Alex Mascarell contributed in several ways to this note.


Resumen. Un Corvus albus viajero. El 4.3.2011 Léa Beligné descubrió un cuervo pío (C.albus) en un parque de Tarragona ciudad, cerca del mar. El ave tenía una anilla de pvc verde con las letras 'CY' en la pata izquierda. El día 9.3, cuando se supo de la cita, Albert Cama relocalizó el ave por la mañana, si bien por la tarde no estaba en el mismo sitio. Investigaciones por internet mostraron que era un ave procedente del Zoo de Barcelona de donde se había escapado diez dias antes. Corvus albus es un divagante accidental al Paleártico donde hay contadas citas en el norte de África si bien unos pocos ejemplares han criado en el Sáhara Occidental (Batty 2010). Por su parte el ave es capaz de aprovechar los barcos para desplazarse (e.g. Martínez & Baroné 2006), lo cual podría explicar algunas de las citas españolas, si bien la presente observación demuestra que un ave que había permanecido largo tiempo en cautividad ha sido capaz de desplazarse 100 km en pocos dias y que ante observaciones de esta especie la proximidad de un puerto importante, como el de Tarragona, no implica una necesaria divagancia asistida.


Resum. Un Corvus albus viatger. El 4.3.2011 Léa Beligné va descobrir un corb de pit blanc (C.albus) a un parc de Tarragona ciutat, prop del mar. L'ocell portava una anella de pvc verda amb les lletres 'CY' a la pota esquerra. El dia 9.3, quan es va conèixer la cita, Albert Cama va relocalitzar l'ocell pel matí, per bé que per la tarda no hi era al mateix lloc. Investigacions per internet van mostrar que era un ocell procedent del Zoo de Barcelona d'on s'havia escapat deu dies abans. Corvus albus és un divagant accidental al Paleàrtico on hi ha comptades cites en el nord d'Àfrica si bé uns pocs exemplars han criat en el Sàhara Occidental (Batty 2010). Per la seva part l'ocell és capaç d'aprofitar els vaixells per a desplaçar-se (e.g. Martínez & Baroné 2006), la qual cosa podria explicar algunes de les citas espanyoles, per bé què la present observació demostra que un au que havia restat llarg temps en captivitat ha estat capaç de volar 100 km en pocs dies i que davant observacions d'aquesta espècie la proximitat d'un port important, com el de Tarragona, no implica una necessària divagància assistida.


1 comentario:

Andrew dijo...

A beautiful bird I have never seen.
Many thanks thanks for sharing.