Ducks flock to Extremadura thanks to its ricefields

Oct 30, 2012
This image shows the Northern Pintail (Anas acuta). Credit: Doviende

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 do not experience significant changes in their winter .

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 Doñana ) or Northwest Africa, where the population of migratory dabbling ducks has also been in decline in recent decades.

Natural versus manmade wetlands

In the 1960's, various large reservoirs were construction for crop irrigation in Extremadura. Then, the relatively small reservoirs were built from the 1990's onwards near the ricefields.

For the purposes of the study, the team first designed and carried out monthly boat trips at specific times with the help of the Guadiana Hydrographic Confederation. In the case of the medium and small sized reservoirs, the birds were counted from the land at places were the whole wetland could be seen.

"We are by no means advocating the construction of new reservoirs to conserve migratory dabbling duck populations. Natural wetlands, in this case the tributary headwaters of the Guadiana River and its flood lands, are vital for biodiversity conservation. They also play a key role in the conservation of aquatic flora and fauna, especially some plants and invertebrate species as well as other aquatic bird species dependent on the marsh habitats of lake and damns," outlines the researcher.

The area making up these four 'new' reservoirs (Sierra Brava, Gargáligas, Cubilar and Ruecas, along with the associated ricefields) is home to an average of more than 1% of Western Europe's biogeographic populations of dabbling duck species such as the Northern Shoveller (Anas clypeata), the Northern Pintail (Anas acuta) and the smallest duck in Europe, the Common Teal (Anas crecca).

"According to numerical criteria established by the Ramsar Convention and adopted by the EU Birds Directive regarding the nomination of Wetland of International Importance (a place that regularly shelters at least 1% of the different biogeographic population), the four reservoirs and the nearby ricefields should become a new Special Conservation Area for Birds (ZEPA), named Vegas Altas del Guadiana," conclude the researchers.

Explore further: Policy action urgently needed to protect Hawaii's dolphins

add to favorites email to friend print save as pdf

Related Stories

Philippines creates haven for endangered duck

Sep 05, 2011

The Philippines has created a protected area to save a species of endangered wild duck, with just 5,000 of the birds remaining, government documents released on Monday said.

New host species for avian influenza identified

May 11, 2007

An eight-year surveillance study, which included more than 36,000 wild migratory birds tested for low pathogenic avian influenza, details new data on host species, prevalence, and temporal and geographical variation of avian ...

North American birds in avian flu study

Oct 23, 2006

U.S. scientists say they've found the common wood duck and laughing gull are susceptible to the H5N1 avian influenza virus and could transmit the disease.

Building a better dam map

Jun 02, 2011

Humans have been building reservoirs and dams for thousands of years. Over the past few decades, their construction has spiked as our need to harness water – critical in flood control, irrigation, recreation, navigation ...

Recommended for you

Protections blocked, but sage grouse work goes on

43 minutes ago

(AP)—U.S. wildlife officials will decide next year whether a wide-ranging Western bird species needs protections even though Congress has blocked such protections from taking effect, Interior Secretary Sally Jewell said ...

Uphill battle to tackle Indonesian shark fishing

9 hours ago

Sharks are hauled ashore every day at a busy market on the central Indonesian island of Lombok, the hub of a booming trade that provides a livelihood for local fishermen but is increasingly alarming environmentalists.

Virus causing mass Cape Cod duck die-offs identified

Dec 16, 2014

Since 1998, hundreds and sometimes thousands of dead eider ducks have been washing up every year on Cape Cod's beaches in late summer or early fall, but the reasons behind these cyclic die-offs have remained ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.