Vultures protect human life
Vultures are often associated with death. However, this attribution is not fair to these flying scavengers, as a recent study shows. In this study, the consequences of a major vulture die-off in India were investigated. The results are surprising.
It was a mass die-off of massive proportions: In the 1990s, millions of vultures died in India - and no one knew why at first. The few surviving carrion-eating birds could no longer fulfill their role in the ecosystem there. With a devastating side effect, as a new study shows: Through the lying carcasses, mortality rates among humans increased.
Vultures, in particular, are remarkably effective at leaving nothing but bones from a carcass - and thus effectively preventing the spread of disease-carrying organisms. According to Anant Sudarshan of the University of Warwick in the UK and Eyal Frank of the University of Chicago in the US, the disappearance of vultures led to over 100,000 additional deaths per year.
In areas with a stable vulture population, a carcass is rarely left undiscovered for long. The large birds with feathered heads dive into it, plunging their curved beaks into the carrion. When the vultures gather, other scavengers have nothing left. Vultures can consume an entire cow in 40 minutes, write the authors.
More street dogs, more rats, poorer water
Other scavengers, such as street dogs and rats, cannot replace vultures in their function, as they leave certain parts of the carcass behind - and thus do not solve the disposal problem. In addition, they can transmit diseases such as rabies. If these animals have more food due to the vulture die-off, their population grows - and with it, the risks for humans.
"Livestock farming will also become a source of water pollution if farmers have to dispose of the dead animals themselves," write the authors in the journal "American Economic Review" further. Farmers often dispose of the numerous carcasses of cows and cattle by throwing them into rivers and lakes, which can lead to further diseases. Other disposal methods, such as burying or burning in crematories, are too expensive or too labor-intensive for many people in India.
For years, no one knew why the vultures were dying
The vulture die-off in India began in 1994. From that year on, farmers used Diclofenac, a powerful anti-inflammatory and painkiller for their cows and other livestock. Vultures that ate the carcasses of these animals later, with traces of Diclofenac still present, suffered kidney damage - which caused the birds to die in agony. The vulture population in India fell from about 50 million to today's approximately one hundred thousand.
The connection to Diclofenac was not recognized until 2004. Although the use of the drug for livestock was banned in India in 2006, it is still used: Some farmers give human-intended Diclofenac medication to their animals. Alternative medicines are available and comparably priced, but they act more slowly.
Sudarshan, who grew up in India, witnessed the population decline himself. "As a child, vultures were everywhere. And then they were suddenly gone," he recalls. Of the nine vulture species found in India, three, which were once particularly common, are now classified as "endangered." According to Sudarshan and Frank, no bird species has been decimated so quickly in human history.
To study the impact on humans, the two environmental economists primarily examined mortality rates in various Indian communities between the years 2000 and 2005. In areas that previously provided suitable habitats for vultures, mortality rates increased after the vulture deaths. In other areas where there were hardly any vultures living before, mortality rates remained stable.
The authors calculate an increase of 4.7% in deaths in vulture habitats. This amounts to over 100,000 additional deaths per year. Given that they had observed for five years, their balance sheet totals over half a million additional deaths. "Before our study, the extent of the problem was not quantified - we knew there were health risks, but we had no concrete numbers before," says Sudarshan.
Billions of Dollars in Damages
The financial damage caused by these deaths amounts to nearly 70 billion Dollars (64 billion Euros) per year, estimate the environmental economists. They consider this a significant figure - after all, wildlife protection also raises the question of how much it can cost. "Given that the problem has now been identified as quite large, it makes sense for India to invest more money in vulture conservation and reintroduction programs, which previously had very few resources available," Sudarshan adds.
The mass construction of animal crematoria, which could potentially replace the functions of vultures, is also very costly, according to Sudarshan - but still cheaper than the health costs of the dead. Costs and benefits are now clear due to the study.
Other countries could also draw conclusions from this, Sudarshan points out. In many parts of Africa, there are still numerous vultures that are at risk of dying in masses due to Diclofenac. "Our study is therefore a warning to developing countries where vultures still exist: act quickly."
Protecting Key Species in the Ecosystem
In general, the two authors advocate in their study that humanity should decide which animals it wants to care for. After all, we find ourselves in the midst of a mass extinction of unprecedented proportions. "Unfortunately, it's impossible to prevent every extinction, so nature conservation policy must address a crucial problem: which of the many endangered species should we protect or reintroduce?"
Currently, a lot of money is being spent to protect especially cute or beautiful animals, adds Sudarshan. This includes pandas or tigers. "We're not saying that's bad, but we want to emphasize that human welfare is interconnected with that of other species." There are key species in the ecosystem that are particularly important for human health and security.
It is essential to identify these species and ensure that they can continue to play their role in the ecosystem. This should also take into account the effects of medicines on animals, says Sudarshan. "Our political recommendation is that new chemicals should be tested for their toxicity not only for humans but also for all key species."
- The decline of vultures in India has led to an increase in pests such as street dogs and rats, as these animals cannot effectively dispose of carcasses like vultures do.
- Infections diseases like rabies have become more prevalent due to the increase in street dog and rat populations, as these animals can transmit such diseases.
- Recognizing the importance of vultures in controlling the spread of infections diseases, education on the role of key species in ecosystems and the potential toxicity of certain medications for these species is crucial for public health and wildlife conservation in India and other countries.
