POOR marksmanship is to blame for the record numbers of waterfowl poisoned each year in Spain鈥檚 wetlands. A report commissioned by the Spanish government, following protests over the huge toll of waterbirds in recent years, says stray lead shot is responsible for the deaths of between 25 000 and 30 000 birds every year.
When large numbers of flamingos died in the Coto Do帽ana in 1991 and 1992, the National Institute for Nature Protection (ICONA) funded a survey of five wetland areas to find out what was killing the birds. The two-year survey, carried out by Rafael Mateo and Raimon Guitart of the Autonomous University of Barcelona, found that every season the country鈥檚 1.3 million licensed hunters leave behind around 3000 tonnes of lead.
For every bird bagged, at least two shots miss their target. And even when a shot succeeds, many of the lead pellets end up in the mud of marshes and wetlands. Waterbirds, which eat grit to help digest food, swallow the lead too, and are poisoned. The most frequent victims are tufted ducks, pintails and pochard.
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鈥淐ompared to statistics for other countries, the concentration of lead in Spanish wetlands is one of the highest in the world,鈥� says Magdalena Bernuez, who coordinated the survey. 鈥淎nd we suspect the mortality rate could be higher, as not all Spain鈥檚 hunting grounds were included in the study.鈥�
The survey found that the El Hondo and La Albufera wetlands in the southeast were the most badly polluted by lead, followed closely by the delta of the Ebro river in the northeast. Samples from La Albufera contained 286 pellets per square metre. This is one of the highest concentrations recorded anywhere in the world, say the authors. 鈥淚f this was Canada or the US, such concentrations would have led to an immediate ban on the use of lead shot.鈥�
Bernuez says: 鈥淲ith that kind of ratio it is virtually impossible for waterfowl to avoid getting pellets in their gizzards.鈥� Digestive juices in the gut dissolve the lead, which is absorbed into the bloodstream. Lead poisoning damages the liver and kidneys and causes muscular and nervous disorders. The birds cannot feed or fly and often fall victim to infections they would normally be immune to. A single pellet is enough to kill.
Waterbirds are not the only victims. Vultures, eagles and buzzards have died after eating poisoned birds. 鈥淭he weakened fowl are easy prey for mammals and birds of prey,鈥� says Bernuez: 鈥淪everal cases of secondary poisoning in raptors and carrion eaters have been detected, including two golden eagles, one of which had 40 pellets in its gizzard.鈥�
Hunters are also at risk if they eat the birds. The liver of a single poisoned bird can contain enough lead to push a person鈥檚 blood lead level over the limit recommended by the WHO.
According to Bernuez, the Spanish Hunting Federation has reacted unenthusiastically to suggestions that it should encourage hunters to switch to other types of shot. 鈥淭heir concern is that other kinds of metal would require the complete overhaul of the kind of weapons used and this is expensive,鈥� she says.