Sep 19, 2024 Vultures in India & Bats in USA: Impact on Animal Welfare & Human Health
A report by Frank and Sudarshan, ecological economists at the University of Chicago, provides an excellent example of how human and environmental well-being is connected to the well-being of animals – in this case, to the health of the vulture population in India. Ecological economics, which integrates economic principles with environmental issues, is the lens through which the authors approach their study. The authors note that the economic cost of a population collapse in a wild animal species is hard to estimate, even if we had reasonable initial estimates of the population of a particular species. Furthermore, the experimental manipulation of an entire ecosystem is likely unethical and not generally feasible. However, the recent catastrophic collapse of the vulture population in India has created a natural experiment enabling Frank and Sudarshan to calculate the economic impact of the loss of vultures.
Vultures provide essential sanitation services by rapidly consuming the carcasses of dead domestic and wild animals. They also play a significant role in an ancient funeral rite of the Zoroastrian faith, where the bodies of deceased adherents are left in a ‘Tower of Silence’ to be consumed by vultures. However, the vulture population in India has dropped by more than 90% as a result of poisoning by diclofenac. This relatively new anti-inflammatory drug began to be used to treat farm animals when generic (and cheaper) drug versions became available after 1993. Even at relatively low residue concentrations in the carcasses of dead domestic livestock, diclofenac proved lethal for vultures. The first reports of declines in the Indian vulture population began to appear in 1996.
The collapse of the vulture populations in India has not only led to a significant increase in all-cause human death rates in areas suitable for vultures but also resulted in substantial economic and ecological losses. The Chicago economists found that districts suitable for vultures saw an average increase in all-cause human death rates of 4.7% in the years following the collapse. They calculated that 430 million people in India lived in vulture-suitable districts and that an average of a little more than 100,000 additional human deaths a year occurred in these districts after the vultures disappeared. The additional annual mortality damages were calculated to amount to $69.4 billion, underscoring the far-reaching impact of the vulture population decline.
The authors concluded that the “vulture is not a particularly attractive bird and evokes rather different emotions at first sight than do more charismatic poster animals of wildlife conservation such as tigers and panda bears. Our results suggest that subjective existence values alone may not be the best way to formulate conservation policy.”
Frank followed up this study with another (published recently in Science) that looked at the economic and human mortality impacts of bat white-nose syndrome in the USA. This fungal disease was first observed in bats in 2006 in New England and has spread westward across the United States. More than 70% of affected bats die, leading to a dramatic drop in local bat populations and a consequent loss of the insect pest-control services provided by bats (who consume their body weight in insects every night). The bat die-off created another natural experiment that Frank has exploited. He examined the county-by-county use of insecticides, farm revenue, and internal infant mortality (excluding deaths from accidents and homicides). On average, in counties where bat populations had fallen due to white-nose syndrome, insecticide use (but not fungicide or herbicide use) increased by 2.7 kilograms per square kilometer of farmland and infant mortality increased by 0.54 deaths per 1,000 live births, reflecting mean increases of 31% and 7.9% respectively relative to the averages for those counties before the advent of white-nose syndrome.
According to Frank’s calculations, the decline in bat populations was associated with a lower farm revenue and a total loss to farmers of nearly $27 billion from 2006 to 2017.
Frank’s findings astonished several scientists who commented on the paper. Paul Ferraro, a sustainability scientist at Johns Hopkins University, stated that the findings are “pretty dramatic” and will “get a lot of attention.” Tracey Woodruff, an environmental health scientist at the University of California San Francisco, stated that the increase in infant deaths is “huge.”
Frank’s report will likely stimulate a resurgent concern about the impact of industrial chemicals on human health and mortality. In 1985, Edith Efron’s book, The Apocalyptics, examined the concerns and regulation of industrial chemicals and their connections to cancer incidence in the United States. She argued that environmentalists and government regulators were overstating the dangers of industrial chemicals. However, Frank’s findings indicate that we might wish to re-examine the regulation, use, and costs of insecticides.
For WellBeing International, the findings on the importance of vultures and bats to human well-being reinforce the need to consider the well-being of not just humans but also of animals and nature in examining sustainable development because we are all part of the same ecology and adverse impacts to one of the people, animals, environment triad will likely lead to adverse effects on the other two. There are additional examples besides those described for bats and vultures. By now, most people are probably vaguely aware of the threats from insecticides to natural pollinators, the global food system and insectivorous bird species. Pollinators provide an estimated $500 billion of value to the global food system. Wolves are another example of the connections between animal and human well-being. Wolves provide value by reducing the frequency of car crashes and associated human injuries with deer. At the same time, Island Conservation demonstrates that removing invasive species such as rats from islands benefits the seabirds that nest on the treated islands and enriches the biodiversity and productivity of the sea around those islands.
Research has shown that the absence of biodiversity services provided by vultures and bats can put humans at risk. Understanding the complex connections between humans, wildlife, and the environment is important. If we investigate and comprehend the indirect losses resulting from disruptions in these connections, we may take advantage of opportunities to address harmful changes earlier and at a lower cost.