German Eagle Flourishes as Farm Runoff Boosts Fish Stocks
The white-tailed eagle, Germany’s national emblem, has tripled to record levels since East joined West in 1990 as conservation programs nurtured their growth. Behind the population boom may be murkier roots: farm runoff.
The agriculture industry inadvertently boosted the fish the eagle feeds on when runoff added nutrients to waterways, helping them flourish while suppressing other flora and fauna in a process known as eutrophication. Corn farming that fuels biogas growth in Germany indirectly spurred the comeback of Europe’s biggest eagle, almost wiped out by bounty hunting 100 years ago.
“There’s nothing comparable in the past century,” said Peter Hauff, coordinator for white-tailed eagles in the Baltic state of Mecklenburg-West Pomerania, which has Germany’s largest number of eagles. “There are now probably more eagles in Germany than at any time in the nation’s history,” he said in an interview at his Neu Wandrum village farmhouse.
The fish-eating raptor with a wingspan of up to 2.5 meters (8.2 feet) isn’t the only beneficiary of the shift to biogas as fish-eating ospreys and cormorants as well as cranes also gained amid the increased use of fertilizer and crop sprays on German farmland.
Cranes profit from winter forage in picked corn fields and are also expanding. At the same time though, birds that feed on insects or require ground cover to nest including the spotted eagle, partridges, larks and other songbirds are in decline.
“As much as 40 percent more fertilizer is needed for corn using standard methods than for rye or oats,” Uwe Naujoks, director of Agro Saarmund eG, which farms 3,700 hectares (9,140 acres) southwest of Berlin, said by phone. “Modern fertilizing systems can use less and soil quality also plays a role.”
The amount of corn grown in Mecklenburg-West Pomerania rose to 151,900 hectares in 2012, up from 89,600 hectares in 1991, according to data from Germany’s Federal Statistics Office. Nationwide, corn production expanded to 2.6 million hectares in 2012 compared with 1.6 million hectares in 1991.
The number of biogas plants in Germany has almost tripled since 2005 to about 7,600 units with a combined capacity of about 3,200 megawatts at the end of last year, according to estimates from the German Biogas Association, an industry group.
“The exponential eagle increase is partly because of protection measures but it’s mainly due to eutrophication of lakes and rivers from farm-fertilizer runoff that’s caused a big increase in fish,” Hauff said. Fish, along with waterfowl, are a major food source for white-tailed eagles. The eagles are related to the U.S.’s bald eagle.
Bream, a freshwater fish that favors slow-moving waters fed by runoff, is increasing with eutrophication, Hauff said.
Hauff tallied 730 breeding pairs of white-tailed eagles in Germany compared with 15 recorded in 1900 when the species came close to extinction. Almost 2,000 pairs have been registered across central Europe, he said.
Eagles faced setbacks in the 1950s and 1960s when DDT was widely used. The insecticide, which made the birds’ egg shells too thin, was banned in 1972 by the Federal Republic of Germany.
WWF, the non-governmental conservation group still known in some countries as the World Wildlife Fund that campaigned to ban the chemical, hails the ban and subsequent population increase in the white-tailed eagle population as a “WWF success” on its German website.
Other WWF conservation efforts have included 24-hour volunteer guards posted at nesting sites to stop collectors from stealing eggs and buying habitat to protect nests.
Thomas Neumann, the WWF’s white-tailed eagle project director, balked at some of Hauff’s comments, saying “white-tailed eagles flourish in areas where there’s no pollution and they prefer bigger fish.”
“That too much fertilizer is being used is a problem, that’s clear,” Neumann said by phone from the west German city of Moelln.
Neumann’s also worried people may get the wrong message, thinking “everything’s okay with the environment” as a result of the revival. “You have to be careful what you say, otherwise farmers will claim it’s thanks to fertilizer that there are more eagles,” he said.
While the DDT ban was the “decisive turning point” for eagles and other birds of prey, Hauff said rising food supply has been the long-term motor, fueling the population growth of white-tailed eagles and other fish-eaters such as cormorants in Germany.
In contrast, he said, the lesser-spotted eagle, although also benefiting from the DDT ban, has been in a slow population decline in Germany for decades.
“They don’t have enough food in our intensively farmed country,” Hauff said. “More and bigger corn fields and fewer pastures means fewer mice, frogs and large insects that are their prey. They’re the losers of modern farming.”
Runoff and eutrophication of Baltic lagoons increased from the mid-1950s through the 1980s, according to reports on the website of Mecklenburg-West Pomerania’s State Agency for the Environment, Nature Conservancy and Geology. Runoff has since been reduced yet eutrophication hasn’t declined given the long-term effects of nutrient enrichment of marine habitats, according to the reports.
“The biggest chronic problem of the Baltic Sea is the constantly increasing eutrophication,” researchers wrote on the Mecklenburg-West Pomeranian government’s website.
Data from the state’s statistics office shows the amount of nitrogen, phosphate, potash and agricultural lime used to fertilize fields has risen. Since records were first kept in 1993-1994, nitrogen use rose from 113 kilos (249 pounds) a year per hectare to a high of 164 kilos a year in 2007-2008 before falling to 140 kilos a year in 2010-2011.
In contrast to farm runoff, sewage treatment plants built since German reunification have led to cleaner water in many areas, said Mario Voigt, deputy head of Mecklenburg-West Pomerania’s State Fishing Association.
“This has led to more trout and whitefish,” Voigt said in a phone interview.
Fish numbers in the Baltic are also increasing -- partly due to stricter fishing limits -- and more and more eagles are nesting on the island of Ruegen close to its fish-rich lagoons and coastal waters.
“The fish population in the Baltic Sea has grown,” Martin Clemm, a lawyer and long-time fisherman who this year released the fishing app “Lure-Skill” that makes recommendations based on weather, target species and fishing spot. “The amount of small cod has significantly grown.”
Hauff declined to predict what the population of white-tailed eagles in Germany may end up being. The WWF’s Neumann thinks there will ultimately be 2,000 breeding pairs in the nation, including along the Rhine River.
Chancellor Angela Merkel says her government backs measures to protect the environment. Eastern Germany is “a model for all areas of nature conservation,” Merkel said in her weekly podcast on May 18.
There’s even friendly debate over which type of eagle is depicted in the German or Prussian coat of arms. The WWF said the white-tailed eagle is the German national bird and Die Welt newspaper said it was also the Prussian national bird.
Birgit Landskron, a spokeswoman for the German parliament in Berlin, said that as a stylized depiction of an eagle, a coat of arms doesn’t represent a particular species.
“It’s a heraldic eagle and not a specific type of eagle,” she said by phone.
Hauff begs to differ. “The white-tailed eagle is in reality a lazy son-of-a-gun,” he said. “They don’t defend their food territory,” he said with a laugh, adding that he thinks the golden eagle was the model for Germany’s national bird.
Hauff, who has been working with the white-tailed eagle for 50 years, said he’s not “entirely happy” about the white-tailed raptor’s comeback.
“I cannot shout hooray or claim it’s only due to the conservation measures that I’ve backed,” he said. “Far more animals are on the defensive due to eutrophication and tackling this is a huge future task.”
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