The decline of the rook Corvus frugelegus wintering population in Spain, a nexw case of "short-stopping"?

Published:

Volume 55(2), December 2008. Pages 229-235.

Language:

Spanish

Original title:

La graja Corvus frugilegus deja de invernar en España: ¿Un nuevo caso de acortamiento en las migraciones?

Abstract:

Wintering Rooks were commonplace in Spain at the beginnings of the 20^th century. In the seventies the wintering population was still present in both the southern and northern plains and in the Ebro Valley. In the winter 2004-05, a maximum count of only 100 birds in two roosts was recorded, one in Valladolid and another one in La Rioja. In the winter 2006-07, only a flock of 50 birds wintered in the Rioja. Migratory Rook populations tend to make shorter movements from the breeding sites to new, more northerly, wintering grounds. This means a definitive isolation of the León breeding population, making it more vulnerable.