In the high mountains of the American West, there’s a tree called the whitebark pine that both humans and other animals have come to rely on. Another practicality: Humans have recorded bird populations for generations. Birds often meet the technical criteria, such as sensitivity to environmental changes. (India has the world’s highest human rabies rate.) McCarty is among the researchers who have used tree swallows to study the impact of a wide range of toxins: PCBs in the Great Lakes and Hudson River, pulp-mill effluent in Western Canada, petroleum in Wyoming’s North Platte River, metals in New Jersey. There are no safe pesticides that kill the insects, and attempts to control them with parasitic wasps show, at best, limited success. Right? As the climate starts warming, are we seeing birds arriving earlier? The boxes attracted insect-eating birds, which in turn devoured 3.5 times more larvae than in control plots with larvae but no boxes. Borers are the bane of coffee farmers, many of whom are small landholders in developing countries. But personal incomes are so meager in Jamaica that without sufficient bird populations “it might render the coffee enterprise not viable for a small farmer.” At the time of the study, the average per-capita gross national income in Jamaica was $3,400, which made the $1,500 in services that birds delivered to a 12-acre farm substantial. Pest control, public health, seed dispersal, ecotourism, environmental monitoring—these are some of the ways birds benefit humans. “I look at them and go, ‘Thank you for working for us.’ ”. Birds are the prime source of food for humans. He calculated that the sites generated $26 million and created 283 jobs in 2011. Are the Trump Administration's Environmental Rollbacks Built to Last? Their presence reduces the danger of avalanche. • Birds possess skills that historically made them useful to militaries. Sometimes their interests coincide perfectly with a tree’s. The collective term for the many ways birds (and other animals, plants, and landscapes) support and improve human life is “ecosystem services.” Understanding these services, and quantifying their dollar value, has been a growing priority for scientists worried about the unprecedented loss of biodiversity we’re now seeing—by one popular estimate, some 27,000 plant and animal species each year, many of them driven extinct by human activity. Fortunately, farmers can enlist help from wintering waterfowl that travel along the Pacific Flyway. • Pollination is often the realm of bees, bugs, and butterflies. Halsey, who now lectures at London’s University of Roehampton, says energy levels might have to increase if climate change or overfishing makes food more scarce. They keep the furniture industry supplied with timber. They assist germination when they eat fruit by removing the pulp and scratching the seed coat. The tiny insects take over individual berries and spend almost their entire life cycles inside, rendering those beans unsellable. “For better or worse, economic arguments tend to get more attention in political debates,” says Geoffrey Heal, a microeconomist at Columbia University Business School. In the 1990s a New York Zoological Society biologist computed that in the jungles of Peru “a single free-flying large macaw might generate $22,500 to $165,000 of tourist receipts in its lifetime.” Around the same time, researchers estimated the annual value of flamingo viewing in Kenya’s Lake Nakuru National Park at $2.5 million to $5 million. Vultures are particularly valuable in India because Hinduism prohibits the slaughter and consumption of cows. Their work has shown that contaminants that land in aquatic sediment don’t remain there; they work their way up the terrestrial chain. They produce eggs and also meat. Bald Eagle. Birds, spiders, and dragonflies rely on bees as their source of food for generating the energy they need to survive. Scientists use bird abundance to measure everything from wetlands health to radioactive contamination. This guano leaches into the ocean and fertilises nearby communities such as coral reefs. Economist Anil Markandya has estimated almost 40 million additional dog bites in India between 1992 and 2006, resulting in about 48,000 extra deaths. “The people were in despair. One hypothesis suggests that without palm wood to build fishing canoes, a culture advanced enough to carve the island’s iconic stone statues fell into steep decline.