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Swallows Arrive in European Winter |
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Many bird species are migrating early to Europe from Africa. Ornithologists believe climate change is the cause behind the new travel habits of swallows, ducks, storks and geese, and could be a threat to their reproductive cycles.
PARIS - The workers at Marquenterre nature park in northern France began noting a decade ago that the springtime arrival of migrating swallows and other birds began to occur weeks earlier than normal, a change that experts attribute to global warming.
Among the species migrating to Marquenterre, in the delta of the Somme River, there are not only swallows (of the Hirundinidae family), martins (Butorides virescens), nightingales (Luscinia megaryhnchos) and larks (Alaudidae family), but also such exceptional birds as the beautiful avocet (Recurvirostra avosetta), with its silky black and white plumage, long blue legs and a long, slender curved beak, whose movements are reminiscent of a ballerina.
But over the past 10 years, members of this species and others began to move their arrival date to early February, the middle of the European winter, when they should have remained at their warm and sunny winter homes in Africa. Other birds noted in this phenomenon include the Eurasian spoonbill (Platalea leucorodia) and the grey heron (Ardea cinerea).
The change has fed concern among ornithologists and other European researchers, who fear that the intensification of the greenhouse effect has already had a decisive impact on the behavior of migrating birds, and of animals in general.
The greenhouse effect is a natural atmospheric phenomenon that helps maintain the Earth's surface temperatures by retaining energy from the Sun, but most scientists in the international community agree that the increased concentration of carbon dioxide from the burning of fossil fuels has intensified the effect, gravely altering average temperatures and causing the polar ice caps to melt and ocean levels to rise.
"For the past 10 years we have seen that the increased clemency of the European winters has modified the behavior of many migratory species," Marquenterre ornithologist Philippe Carruete told Tierramérica.
"Many birds, including ducks, storks and geese, which normally migrated from Northern Europe to Africa in the autumn, now spend half the winter in our nature park," he said.
Scientific studies conducted in other European countries suggest similar circumstances associated with climate change, said Carruete.
"In the countries of Northern Europe, the tundra is diseappearing, threatening the survival of many species that inhabit that region. In Africa, desertification is also reducing the habitat of migratory birds during the northern hemisphere winter."
"Because the birds have memory, after years of suffering the consequences of those changes in the vegetation of Northern Europe and of Africa, they have learned to save themselves the trip, and to search for appropriate habitat in Europe during the winter," said the expert.
Storks (Ciconia ciconia), ducks (Anatidae family), grey heron and other migratory birds do not flee the cold, but rather the lack of food that arises towards the end of Boreal summer. To reach Africa, they are guided by the Sun, the stars and by the Earth's magnetic field.
The findings of the Marquenterre ornithologists coincide with those of scientists from the Max-Planck-Gesellschaft, a German research institution, and from the Sempach Ornithology Institute in Switzerland.
In a study conducted in the Bretolet Pass in the Swiss Alps, Lukas Jenni, director of the Sempach, established that many birds have begun to fly to Africa in the middle of the summer, and return to Europe in the middle of the winter, among them the bird of paradise (Apus apus), the warbler (Sylvia borin) and the pied flycatcher (Ficedula hypoleuca).
Jenni, who published his findings in the journal Proceedings of the Royal Society, based his conclusion on Bretolet Pass observations since 1965 of some 350,000 migratory birds representing 65 species.
By influencing the migration habits of different species, climate change reduces their incubation and reproductive periods, threatening their survival, according to the expert.
Ornithologists from Max-Planck-Gesellschaft also have found that many birds are returning to their European habitats an average of five days earlier than they used to.
Species like the trumpeter finch (Rhodopechys githaginea), European bee-eater (Merops apiaster) and even parrots are leaving their normal African habitats and are settling in the Mediterranean region, and even in Central and Northern Europe.
Despite the evidence that confirms the consequences of carbon dioxide emissions for the Earth's climate -- such as drought, forest fires, heat waves, torrential rains, floods and severe storms -- climate change continues to be a subject of much controversy.
There are some scientists who have called into doubt the climate change phenomenon itself, while the United States, the world's leading producer of greenhouse gases, refuses to ratify the Kyoto Protocol, established in 1997, which obligates industrialized countries to cut their emissions 5.2 percent by 2012, based on their 1990 levels.
* Julio Godoy is an IPS correspondent
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