Europe's fabled white stork is flourishing in some unlikely places on the Iberian Peninsula
- Howard Youth
- Aug 01, 2002
EVERY THURSDAY, you can find José Aguirre bobbing and weaving his mud-spattered green van through a grimy gauntlet of potholes, trash hunks and roiling trucks. Dressed in khakis, a green sweatshirt and sporting short-cropped dark brown hair, Aguirre looks like he could drive military vehicles. Instead, the Complutense University of Madrid biologist studies white storks living around Spain's growing capital. Some days he's sloshing across pastures, others he's in the suburbs. Today, he's surrounded by trash.
"This part of Madrid Province is not the prettiest place in the world, but the storks love it," says the 28-year-old scientist, parking in the heart of Madrid's largest dump, the Las Dehesas landfill. Apparently immune to fermenting garbage fumes, he peers through a spotting scope at 150 white, black-winged birds that dot plastic-bag-spangled trash mounds. Some of the three-foot-tall birds reach over smaller black-headed gulls, thrusting their sharp, red bills at meat scraps. But most, apparently satiated, stand like huge lawn ornaments, ignoring the smoky comings and goings of bulldozers and dump trucks.
THE HIGH LIFE: Stork nesting places in Spain range from the artistic to the quixotic. A sculpture near Cáceres is home to the birds shown here. Adult pairs often return and add on to old nests, creating behemoths that can weigh as much as half a ton.
Photo: © JOHN CANCALOSI
"One of the main reasons for the increase of storks in Madrid Province is rubbish dumps," says Aguirre, scribbling down the band numbers he spies on the lounging birds' legs.
Trash eaters? Aren't storks supposed to be stately creatures, delivering bundled babies and bringing good fortune? The creatures of myth, it turns out, bear very little resemblance to the white storks of reality. And the fortunes of the real storks have lately traced a twisting path because of pollution, habitat loss, drought--and rubbish. Spain is both a major migration stop and breeding hub for storks, and therefore provides a perfect setting for unweaving the tangled tale of the stork. And Madrid's trash dump provides an excellent, if unlikely, stage for this drama.
The story begins before humanity and garbage. Fossils reveal that white storks appeared during the Miocene Epoch, between 24 and 5 million years ago. The leggy birds stalked open, grassy areas and wetlands teeming with insects, frogs, fish, rodents and other small animals. In more recent millennia, stork-feeding acreage grew as early Europeans cut their forests, creating fields and rough, oak-studded pastures called dehesas. As settlements peppered the landscape, rooftops--particularly church steeples and other high points--attracted nesting storks seeking safety from terrestrial predators.
Villagers protected the attractive, pest-eating birds that piled their bulky stick nests atop their rooftops, weaving them into lore and legend. In Scandinavian, Dutch and German stories, storks brought babies upon their spring arrival. The white stork became Lithuania's national bird and Spanish and Ukrainian proverbs state that it brings good luck. Far south, African villagers call them "grasshopper birds" because large wintering flocks follow locust migrations through the Sahara's southern fringes.
"The white stork is known to everyone in Europe, to adults and to children," says Juan Carlos Atienza, who studies stork conservation issues at the Madrid-based Spanish Society of Ornithology (SEO/BirdLife). "It nests on rooftops. As such, it's a very charismatic bird--a very special bird." White storks also nest along North Africa's coast and into Asia as far east as Uzbekistan. Some pairs breed in South Africa, where far more winter. All told, white storks are found in almost 80 countries. While 18 other stork species live on all continents except Antarctica, only one other--Africa's Abdim's stork--regularly nests on people's homes.
It wasn't long ago that people feared they would lose their neighborhood storks. The stately birds took a dive during the twentieth century as agriculture changed, wetlands were drained and towns sprawled into cities. The tailspin accelerated after World War II and hit Western Europe the hardest. A 1984 international white stork census found declining populations in all stork-inhabited Western European countries. Even Spain's hefty population dropped by half, prompting the Spanish government to declare the species "vulnerable," a protected status that still stands.
Experts fingered various reasons for the decline, including pesticides, power line collisions and electrocution, hunting in Africa and habitat loss. But most experts agree that an almost-20-year drought cycle on the birds' West African wintering grounds played a major role. Nearly 80 percent of wildlife habitat in key stork wintering countries such as Senegal, Mali and Niger was lost during the drought, according to one estimate.
In a remarkable rebound, however, the stork population roared back during the 1990s, swelling by 23 percent--from about 135,000 breeding pairs to around 166,000, according to a 1994 95 census. While many experts attribute the recovery to the return of wet winters to storks' sub-Saharan wintering grounds, others wonder if part of the rebound stems from a change in stork feeding patterns, such as those seen in Western Europe's stork capital, Spain. Between 1984 and 1994, the country's stork population shot from 6,700 pairs to 16,600--an almost 150 percent rise. One in ten of the world's white stork pairs now nest there.
In Spain's south and center, dry and warm weather nurtures nestlings, while natural conditions favor stork-friendly agriculture--rough pastures and fields left fallow to "rest" marginal soils. But new attractions await storks lingering there. For example, during the past few decades, the red swamp crayfish, introduced from the Americas, became abundant and storks now fish them out of rice fields, irrigation channels and other habitats that have replaced wilder feeding grounds.
Then there's Spain's odiferous landfill network, which remains open all year and provides rest and refueling stops for wayward migrants and dinner hangouts for local nesters. "I'm convinced that garbage dumps in Spain are the most important resting areas for the storks," says Holger Schulz, a biologist with the Swiss Society for the White Stork who visits Spain regularly. Aguirre and his colleagues agree. "We estimate that almost 45 percent of the entire Western European population goes through the dump and stops here to eat and rest," says Aguirre.
August is high season for Western Europe's young and adult storks, which stream south toward West Africa. During this month, as many as 1,700 show up at Las Dehesas in a day. Further south, as many as 15,000 a day turn up at a dump near the Strait of Gibraltar, over which most of the birds cross en masse to Africa. (Eastern Europe's storks, which constitute a more stable and larger population, skirt the Mediterranean's other shore, crossing the Bosporus Strait in huge flocks, then working their way to East and southern Africa.)
Along the western route, many storks now cut their Africa stay short, or don't reach there at all. "About half of the birds we marked with satellite transmitters did not continue on to Africa--they stopped in southern Spain," says Schulz of 25 French and Swiss storks that he has been tracking. These days, Spain hosts at least 3,000 wintering white storks, while at least 1,000 more hang out in nearby southern Portugal. "It's easy to say that storks go to Africa and come back. Quite a few do that, but not all," says Aguirre.
Whether they journey all the way to Africa or not, adult white storks reappear on their European nesting grounds in late winter and early spring. The birds then pair up, cementing bonds through sessions of head bobbing and bill clattering, a ritual during which first one, then the other bird slowly leans back its head and neck, snapping its bill all the while. This hollow rattling often carries half a mile.
On a sunny March afternoon, Aguirre checks on the breeding progress of storks in Rivas-Vaciamadrid, a little town about a mile away from the dump. Clattering stork bills sound off all around as he swings his binoculars toward a pair mating on an easy-chair-sized mass of sticks atop the town's terra-cotta church roof. The slightly larger male straddles his mate, flapping his six-foot wingspan under a deep blue sky. Down the street, stork pairs and their nests dot radio and cell phone towers, the sign at the Metro station--even a power pole in the dusty yard of the Stork Public School.
The same pairs often nest together year after year, but not always. "For years, scientists thought they couple up for a lifetime, but we've seen that it isn't quite that simple. There are couple changes, trios, things like that," says Aguirre. Nest location, more than anything else, seems to reunite couples. "Pairs split up after the breeding season and often meet again in the following year as they prefer to use the same nest again," says Schulz.
White stork pairs nest alone or in close proximity to others, assembling bulky nests atop church steeples, towers, pylons, trees, ruins and on rare occasions cliffs or construction cranes. Frequently, pairs embellish old nests. Over the years these stick masses often become monstrosities. Some reach six feet wide, more than ten feet high and weigh as much as 1,000 pounds--heavy enough to crack an old roof or shatter its shingles. "Most priests in Spain don't like storks because they make them fix their roofs," says Aguirre, pointing out scattered broken tiles atop the church.
Both parents share incubation duties, shielding their three to five white, lemon-sized eggs from wind, rain and sun. Meanwhile, along the nests' raggedy edges, sparrows, starlings, jackdaws and other birds move in and raise their own young. After about a month, the stork nestlings hatch and parents regurgitate food onto the nest floor for them. Young stay at the nest up to two months, graduating to solid food and exercising their wings before finally flapping off to follow parents to favored feeding spots. Young storks often breed at two or three years of age. Some live 20 or more years, raising 10 to 20 young in a lifetime.
Although many of Madrid Province's 900 or so nesting pairs feed at dumps, their just-hatched nestlings receive choice tidbits caught at surrounding dehesas and wetlands. "What we have seen is that adults mainly feed their young natural foods from around here--beetles, grasshoppers and some small frogs, snakes and lizards. What they keep for themselves or older chicks is food from the dumps," says Aguirre, who along with his colleagues carefully examine pellets that storks regurgitate daily.
As the Madrid nest-lings grow, however, their willingness to sample just about anything can get them into trouble at the dump. Some eat rubber bands, sponges or other synthetic objects that snag in their digestive tracts and kill or sicken them. Toxic substances likely poison others.
NESTING INSTINCTS: Although reputed to bring babies and good fortune to people, storks can more often be seen in Europe carrying sticks for nests. Mates generally reunite at nests each spring and raise two to four young each year. While the parents may nourish themselves and older chicks with scraps from landfills, the young nestlings receive natural fare caught in fields or wetlands. But many of the storks' natural feeding and roosting habitats have been lost to drought or development.
Photo: © JOHN CANCALOSI
Ironically, dumps may soon become endangered habitats as well. In the next decade or so, Spain, via a European Union directive, hopes to compost all large towns' and cities' organic waste. While environmentally beneficial, this change will affect storks where they mass along migration corridors or where large populations nest, such as near Madrid's Las Dehesas. "We are concerned that the administration is not analyzing the effect that changing their management model for dumps might bring to species that feed in them," says SEO/BirdLife's Atienza. "They have to take into account that the white stork, like other species using the dumps, is protected by European and Spanish legislation."
Some conservationists are pondering measures that might help the birds, such as keeping parts of landfills open so that storks can feed on trash before it's sorted and recycled. Dumps may supplement stork diets and compensate them somewhat for habitat loss, but wetlands, dehesas, and other wild habitats remain vital for successful breeding.
Loss of these natural habitats is among the worries nagging scientists monitoring the white stork. But there are other dangers. Most Western European birds still winter in West Africa, so another prolonged drought there could spell disaster. Power line collisions and electrocution kill many birds, as Schulz and his colleagues found during their last visit to Spain. They found 127 dead storks littering a four-mile stretch of power pylons and estimated that at least 1,000 die there every winter. Hunting in Africa also exacts a considerable toll. Meanwhile, pesticide applications both north and south wipe out stork prey and may endanger the birds. For example, Spanish rice farmers spray pesticides to battle the in- troduced crayfish, a potentially harmful side effect of the new stork food bounty that Schulz hopes to study.
For now, however, white storks are winging their way back, a fact that's easy to see if you tag along with Aguirre as he drives around Madrid Province or lists a rising tide of stork band numbers at the dump. Fortunately for the storks, many hard-working biologists like Aguirre have dedicated themselves to demystifying the storks' wobbly status. "Some people might think everything's known about storks. But there is still plenty to learn," he says.
Back at the dump, a fiery orange sun sets behind Aguirre's van. All at once, the 150 storks take off--a spectacular flurry of white, black and scarlet headed for nearby riverside roost trees. "If you think this is great, you should have been with me a few years ago near Gibraltar. During migration, I saw a flock of 15,000 flying over my head toward Africa. I couldn't believe it," says Aguirre. "I cried."
Madrid-based writer Howard Youth frequently searches the Spanish capital's outskirts for storks and other birds.
Opposite but Alike
Europe's other stork, the black stork, avoids human settlements, nesting in trees or on cliffs hidden deep within untouched wild landscapes. Perhaps not surprisingly, the white stork's country cousin is not as well studied and also far less common. This striking black bird, with white belly and candy-apple red bill, legs and eye ring, has the widest range of any stork species, breeding on the Iberian Peninsula, in Eastern Europe, Russia, and all the way to Korea, but wintering in Africa and southern Asia. In recent years, black storks have recolonized parts of their range, including sites in France and Belgium, where farmlands have returned to forest. They also expanded their Russian range to the east, as have white storks.–Howard Youth
By expanding its range, North America's only native stork is slowly recovering from a century of swamp draining in South Florida. To learn more about the wood stork's improving outlook, see "Coming Back on Its Own Terms" (National Wildlife, April/May 1998).