Europe’s eagles under threat from vulture-killing drug

A drug that has already obliterated many of India’s vultures is now threatening eagles and vultures in Europe and Africa. Golden eagles may be among the species at risk.

India’s Gyps vultures began disappearing in the 1990s. They were succumbing to a painkiller called diclofenac, which was given to cattle. The drug lurked in the cattle carcasses that the vultures feasted on, got into the birds’ bloodstream and destroyed their kidneys.

Now it seems diclofenac has the same effect on eagles, which also feed on cattle carcasses. Yet the drug has recently been approved for use in Spain and Italy, home to some of Europe’s biggest populations of vultures and eagles.

Dying raptors

In February 2012, two dead steppe eagles (Aquila nipalensis) turned up in a dump for cattle carcasses near Bikaner, in Rajasthan, India. Anil Sharma and his colleagues from the Indian Veterinary Research Institute in Izatnagar found telltale signs of kidney failure such as uric acid crystals.

Kidney failure is also typically seen in vultures that have died after eating cattle treated with diclofenac. Sharma also found traces of diclofenac in the eagles’ tissues, at the same levels seen in killed vultures.

This does not prove that diclofenac killed the eagles, says Sharma, but this is how the drug kills vultures. If the drug is to blame, it is bad news for steppe eagles, many of which winter in India and rely on cattle carcasses.

Family affair

Steppe eagles may not be the only birds at risk. At least five of the eight species in the Gyps genus are susceptible to diclofenac. If the steppe eagle is susceptible, the rest of its genus Aquila could be too.

There are 14 Aquila species including several more in south Asia, a few in Africa, and Europe’s golden and Spanish imperial eagles. All scavenge cattle carcasses.

And all are now exposed. Diclofenac was registered for use in cattle in Italy and Spain in November 2013. It has been sold in Africa for veterinary use since 2007, and conservation organisation BirdLife International says the drug is already affecting vulture populations there.

Diclofenac dieback

The Vulture Conservation Foundation (VCF) wants diclofenac banned in Europe and has set up a petition. But they say officials are only offering to change the drug’s label, to recommend it not be given to cattle that are likely to be eaten by vultures.

Europe has spent millions of euros to bring back vultures and eagles, and in 2012 authorised farmers to leave dead animals out for the birds to eat. ” We do not think that a warning will ensure the safety of vultures and eagles,” says Sharma’s colleague Toby Galligan of the Royal Society for the Protection of Birds in Sandy, UK.

Such carcasses may pose a particular threat to eagles. They range widely, particularly golden eagles, whereas European Gyps vultures are restricted to limited feeding places. Toxicologists have calculated that the liver of one treated cow can kill 15 vultures, and eagles are smaller so probably need less to die.

Journal reference: Bird Conservation International, DOI: 10.1017/S0959270913000609

Electronic Smog Disorients European Robins

Radio overload. AM radios and electronics emitting low-intensity electromagnetic waves interfere with the European robin’s magnetic sense of direction.

The traffic reports on AM radio might help humans navigate, but the electromagnetic waves they travel on could have the opposite effect on birds. A 7-year investigation has discovered that radio waves disrupt the piloting systems of migratory European robins. The work, experts say, provides convincing evidence that such transmissions can alter animal behavior.

For decades, people have feared that cellphones, power lines, and other sources of electromagnetic radiation might harm both human health and nature. But don’t fret. Your cellphones are still safe to use in the wild. “Modern-day charlatans will try to exploit this study to claim that cellphone radiation causes damage, but it’s not screwing up the robins,” says geobiologist Joseph Kirschvink of the California Institute of Technology in Pasadena, who was not involved in the study. “It’s telling them to use a different sense.”

European robins, like many migratory birds, can navigate via Earth’s magnetic fields—but they don’t have to. Scientists have known for 30 years that robins’ magnetosense deactivates when it might lead them astray, for instance if they hit a spot where Earth’s geomagnetic field dramatically changes strength. Low-intensity radio waves now join this group of negative triggers.

Biologists at the University of Oldenburg in Germany stumbled upon the phenomenon by accident in 2004 while they were testing a basic feature of European robin behavior. During the spring and autumn, the birds’ urge to travel is so strong that captured individuals will reflexively start jumping in the direction of their migration, even scratching up the bottom of their cages. But when the robins were held in wooden huts on campus, they were suddenly clueless as to which way they were supposed to be going.

So the researchers started experimenting to see why the birds’ compasses appeared to have shut off. Change their food? No difference. Tweak their sleep cycles with artificial lighting? Nada. Finally, they started wondering if the magnetic fields produced by electronic devices on campus might be the culprit.

To find out, the researchers installed aluminum wallpaper inside the birds’ wooden huts. The metal sidings were linked by means of wires to metal rods buried in the dirt outside. When electromagnetic noise struck the aluminum, it was soaked up and passed into the land. Known as “grounding,” this canceled out the electromagnetic noise coming through the huts’ walls, leaving a signal from only Earth’s magnetic field. After the screens were built, the robins aligned in the right direction, the team reports online today in Nature. But when the shields were switched off, the birds became disoriented again.

Given the skepticism surrounding prior research into electromagnetic noise and animal habits, the project leaders used double-blind experiments to replicate the finding. Undergraduate and graduate volunteers ran the trials. Some worked in wooden huts with the shields turned on, while others had them off—but to eliminate bias, the students didn’t know who was working where.

“We added a number of securities to protect ourselves from wishful thinking,” says neurosensory biologist Henrik Mouritsen of the University of Oldenburg, who led the study. “The conditions were repeated with different generations of students, and experiments were blinded on all levels.”

Artificially reintroducing magnetic fields into a screened hut allowed the researchers to pinpoint possible sources of the misguiding noise. The most disorienting electromagnetic noise had frequencies matching those produced by AM radio stations and small devices like electronic article surveillance—those little magnetic tags for clothing at department stores. This is 1000 times less powerful than the frequencies emitted by cellphones and 400 times higher than those produced by power lines. Moving the birds to a rural location without electronic noise immediately restored their navigation skills.

European migratory bird populations are declining. Though habitat destruction is the main suspect, the findings raise questions as to whether humanmade electromagnetic pollution from radio stations and home electronics is a general problem across Europe, or if this phenomenon is specific to Oldenburg.

“I just wonder where this strong field originates,” says retired zoologist Roswitha Wiltschko, who co-discovered the avian magnetic compass with her husband Wolfgang in the 1970s and who was not involved in the work. “We were doing these experiments in the central district of Frankfurt, a major city, and we never had problems with magnetic fields disrupting the orientation of our birds.” Wiltschko feels the study is “really well done” but thinks more research is needed before claiming that this is a general occurrence.

If it is, the effect should be short-ranged and limited to within 5 to 10 km of AM stations, says Kirschvink, who thinks that birds may have evolved this off switch for their magnetic compass long before Guglielmo Marconi invented the radio in order to combat radiation fluxes created by the sun’s activity.