Economics is for the Birds

There used to be a recognized academic field of “economic ornithology”.

It emphasized the economic benefits of birds to agriculture, in their role reducing bugs and weeds.

But with the advent of pesticides, economic ornithology had become obsolete by the 1940s. Robert Francis tells the story at his “Bird History” substack: “Economic Ornithology: Before pesticides, birds were a farmer’s best defense against bugs. And the government’s economic ornithologists could tell you exactly how much each bird was worth” (January 10, 2024).

Francis points out:

[The] US Department of Agriculture established the Section of Economic Ornithology in 1885. The following year it became the Division of Biological Survey, and was upgraded to the Bureau of Biological Survey in 1905. …  In 1903, the Saturday Evening Post, for example, published a request that `every person in the United States who kills a bird is requested by the United States Government, not in a mandatory way, but as a matter of courtesy, to send the stomach and its contents to Washington.’ By 1916, the Bureau of Biological Survey had collected and analyzed the contents from more than 60,000 bird stomachs, which they used to determine whether each of the 400 species they studied was, on balance, helpful or harmful to man. Researchers divided the stomach contents into “good,” “bad,” and “neutral” categories, based on whether the partially-digested bug and plant matter was beneficial or harmful to farmers. …

According to the Bureau of Biological Survey, native sparrows, who are “specially efficient destroyers of weed seeds,” saved farmers $35 million in 1906 by eating ragweed and crabgrass seeds. And during Nebraska’s 1874 Rocky Mountain Locust infestation, a single Marsh Wren was calculated to have fed her brood of chicks enough grasshoppers to save $1,743.97 worth of crops. The Bureau of Biological Survey even helped rehabilitate the reputation of some birds that were historically seen as enemies to the farmer. By examining over a thousand crow stomachs, the Bureau found that while crows did in fact pull up sprouting corn and nibble corn on the stalk, they ate more “noxious insects and mice,” meaning that “the verdict was therefore rendered in favor of the crow, since, on the whole, the bird seemed to do more good than harm.”Owls, which were long considered poultry thieves, were proven to eat enough mice to earn back “the small commission they collect” by nabbing the occasional chicken.

This kind of information was distributed not just by the US Department of Agriculture, but also through groups like the Audubon Society and the League of American Sportsmen. For those who would like more history of economic ornithology, Theodore S. Palmer of the USDA provides an overview of the development of the field from the 1850s up through the end of the 19th century in his 1899 monograph: “A Review of Economic Ornithology in the United States.” H.J. Taylor (no relation) provided pocket autobiographies of five “Pioneers in Economic Ornithology” (The Wilson Bulletin, September 1931).

It wasn’t just pesticides that killed off economic ornithology. A deeper issue was that it wasn’t clear that adding birds to an agricultural area actually reduced the number of insects and weeds, at least not in a reliable way. And yet, some occasional modern studies suggest that certain birds in certain settings do have considerable economic value.

My favorite recent example is the “The Social Costs of Keystone Species Collapse: Evidence From The Decline of Vultures in India,” by Eyal G. Frank, and Anant Sudarshan (Becker Friedman Institute Research Brief, February 2, 2023). They tell the story of how a painkiller called diclofenac went off-patent, and as its price declined sharply, veterinarians in India began to give the drug to sick cattle. Although the drug was fine for cattle, it is severely toxic to vultures. Thus, when some of these cattle died and their carcasses were eaten by vultures, the vultures in this area became almost extinct. The authors write:

Vultures are efficient scavengers and feed only on carrion. In India, a country with over 500 million livestock, these birds provided an important public health service by removing livestock carcasses from the environment. In the mid-1990s, vultures experienced the fastest population collapse of a bird species in recorded history. The cause of death was unknown until 2004 when it was identified as poisoning from consuming carcasses containing traces of a common painkiller, diclofenac. The expiration of a patent led to a dramatic fall in the price of medical diclofenac, the development of generic variants, and entry into the veterinary market in 1994. We exploit this event to study the costs of losing vultures. Using habitat range maps for affected species, we compare high- to low-vulture suitability districts before and after the veterinary use of diclofenac. We find that, on average, all-cause human death rates increased by more than 4% in vulture-suitable districts after these birds nearly went extinct. … As vultures died out, the scavenging services they provided disappeared too, and carrion were left out in the open for long periods of time. Ecologists have argued that this may have led to an increase in the population of rats and feral dogs, which are a major source of rabies in India. Rotting carcasses can also transmit pathogens and diseases such as anthrax, to other scavengers. In addition, these pathogens can enter water sources either when people dump carcasses in rivers or because of erosion by surface runoff …

More generally, there continues to be a modest literature in environmental economics that carries on the “economic ornithology” tradition of looking at birds as providers of ecosystem services. Christopher J. Whelan, Çağan H. Şekercioğlu and Daniel G. Wenny provide an overview in   “Why birds matter: from economic ornithology to ecosystem services” (Journal of Ornithology, 2015, 156: 227-238). They point to a few specific studies:

For instance, Mols and Visser (2002) investigated effects of bird control of herbivorous insects in Dutch apple orchards, and reported that increasing bird density through deployment of nest boxes led to a 50 % reduction in apple damage and an increase of about 60 % in total apple crop yield. Koh (2008) attributed bird pest control to prevention of 9–26 % fruit loss in oil palm (Elaeis guineensis). Johnson et al. (2009) found birds significantly reduced damage by coffee berry-borer beetles (Hypothenemus hampei), with higher coffee yields resulting in increased income from US$44 to US$310/ha.

The authors also point to birds as providing pollination and seed dispersal services, controlling populations of mice and rats and other services. But the overall tone of the article is that there is still a lot of research to be done, not in the dissection of bird stomachs, but in understanding the role of birds within ecosystems–especially as bird populations rise or fall and ecosystems adjust accordingly. The authors write:

Yet the economic relevance of birds is not widely appreciated and the economic relevance to human society of birds’ ecological roles is even less understood. Quantifying the services provided by birds is crucial to understand their importance for ecosystems and for the people that benefit from them. In this paper, we briefly review the rise and fall of economic ornithology and call for a new economic ornithology with heightened standards and a holistic focus within the ecosystem services approach. Birds’ ecological roles, and therefore, ecosystem services, are critical to the health of many ecosystems and to human well-being.

For my bird-watcher friends, no, I’m not suggesting that all birds should be reduced to quantifiable factors of production. But when it comes to protecting and restoring bird habitat, having some dollars and cents on your side of the argument doesn’t hurt.