Influence of farming activities in the Iberian Peninsula on the winter habitat use of common crane (Grus grus) in areas of its traditional migratory routes

Farming activities can influence bird habitat and wintering patterns. Chang es in the wintering habitat use of common crane (Grus grus) were related to changes in land use on this species' traditional migration route in the We stern Palaearctics. The study was conducted in the Orellana area (Extremadu ra, SW Spain), the most important wintering area on this route, where the c ontinued availability of natural food resources (acorns, bulbs, invertebrat es) represents a more balanced diet than agricultural resources alone. The presence of crops such as corn (Zea mays I,.) is, however, not a critical f actor in the area, since the two types of resources, natural and agricultur al, are available in the same period of time. The increase in area dedicate d to irrigated crops, especially rice (Oriza sp.), affected the growth in t he numbers of wintering cranes in the Orellana area. In the past the peak w intering period was in December and was positively correlated to acorn prod uction, whereas the peak period is now in January-February, coinciding with the use of rice-held stubble as feeding places. Dehesas (Mediteranean scru b), cultivated or not, may replace rice-field stubble as feeding places. Th e existence of intensive farming activity in combination with traditional l and-uses is suggested to be the cause of these changes. (C) 1999 Elsevier S cience B.V. All rights reserved.