Four new reservoirs linked to rice cultivation built in the middle basin of the Guadiana river in the middle of the 1990's have allowed various migratory dabbling duck species to significantly increase in number during the winter. Researchers at the University of Extremadura propose that Vegas Altas del Guadiana is turned into a new Special Protection Area for Birds.
Many aquatic migratory bird populations are in decline and the loss of natural wetland is one of the main causes. A study at the University of Extremadura financed by the Guadiana Hydrographic Confederation has analysed the migratory patterns of this type of bird both before and after the construction of these reservoirs in the area of Vegas Altas del Guadiana.
"Between 1991 and 1994 around 25,277 ducks spent the winter in the large reservoirs of Guadiana. This number increased to 46,163 between 2007 and 2010 and the vast majority was to be found in the four new reservoirs that are a lot smaller than those in the Guadiana middle basin. On the other hand, the large reservoirs saw an overall decline in their populations during the same two periods," as explained to SINC by Juan G. Navedo, lead researcher of the study published in the 'Bird Conservation International' journal.
According to the scientists, the development of ricefields (also considered as wetlands) is key to the study since the presence of this crop nearby probably ensures that these birds do not experience significant changes in their winter migration patterns.
The researcher emphasises that "the birds only rest on the reservoirs during the day and then flee in mass at dusk to feed in the nearby ricefields. Seeing the ducks take flight is a true spectacle."
Biogeographic populations of these species show a general downward trend. It is estimated that the birds that now spend their winter in Extremadura are probably from Southwest Europe (mainly the Doana Nature Reserve) or Northwe
FECYT - Spanish Foundation for Science and Technology