Impact of heavy rainfall on wading bird numbers

22nd February 2011

Last week we had a lot of rain, high winds and some very dramatic thunderstorms. I’ve commented in recent posts on the noticeable effect this winter’s heavy rains have had on the water levels of the Guadarranque and Barbate reservoirs and a visit to the estuary and lagoon here in Sotogrande at the weekend confirmed there to be high water levels there too. It was interesting then to come across this article in this week’s  ‘Sur in English’ newspaper on the  effects of  the exceptional rainfall levels on the wintering wading bird populations. Although the article quotes numbers of birds and species counted in the neighbouring province of Malaga, I’m sure similar patterns will have occurred here in Cadíz too.

bird numbers in malaga’s wetlands have doubled this year due to heavy rainfall

Figures show an increase in the number of aquatic birds this winter in Malaga province. But at what cost to other species?
22.02.11 – 12:26 – George Prior |Axarquía
Malaga province’s unusually high level of rainfall this winter has meant the numbers of aquatic birds have soared to figures not seen since 1998, according to the Junta de Andalucía.
Remedios Martel, the Junta’s Head of Environment, reports that water levels at the majority of the province’s 28 wetlands are at a ten-year highs and there are more than 60,000 bird wintering in these areas. The census registers 53 different species which is also the highest in a decade.
The investigation shows that more than 60 per cent, or some 37,000 birds, are at Spain’s largest lake in Fuente de la Piedra, including 6,500 flamingos, a particularly high volume for this time of year.
Bob Wright, founder of the association, Birding Axarquía (birdingaxarquia.blogspot.com), says the weather has been a boon for the area’s aquatic birdlife.
“The wet winter we’ve had has certainly attracted water birds. Recently, for example, there were thousands and thousands of Mediterranean gulls on Lake Viñuela; and everything suggests it will be a good season for the breeding pairs of flamingos over the next few weeks too,” explains Bob.
“We’ve registered at least a dozen White-headed Ducks, which are one of Spain’s native, endangered species; it’s a good sign as at one time there were only 11 pairs left in Andalucía. There has also been a significant number of sightings of coots as well as diving birds such as cormorants, as the water is so deep.”
On the flip side, the bird enthusiast warns the picture is not as rosy for other species.
“The Junta de Andalucía is right in its findings that there are significantly more water birds this winter due to heavy rain and high water levels in the marsh and wetlands; but it needs to be stressed that this has also been to the detriment of other species.
“High levels of water in lakes, streams and rivers have meant there are not as many small waders, such as the Common Sandpiper, as there should be, as they feed off small invertebrates and insects in the mud or exposed soil at the edge of a river or lake. Larger waders like storks and herons, are more numerous in comparison this year,” he confirms.
Temperatures
Not only has the winter been wetter, it has also been averagely two degrees colder than the norm. This too has had a knock-on effect for the province’s birds.
“The cooler temperature have prevented many of the migratory birds coming back to this part of Spain,” says Bob Wright.
“We are only just beginning to register species like House Martins and Swallows, which we’ve starting to see again over the last few days; last weekend we also noticed the first Grey Wagtail. But it’s probably still too cold to see swifts just yet though.
“It’s an exciting, if not crucial, time of year for the native and visiting birds of southern Spain. And the latest figures highlight what a huge impact weather patterns have on our wildlife.”
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