Bird populations have been declining over the past half century. Perhaps 40 percent of North America’s birds have disappeared during that time – over 3.5 billion birds! According to the IUCN Red List, 23 percent of the world’s birds are threatened or near-threatened, and 44 percent have declining populations.
On field trips I used to point out a Yellow-headed Blackbird marsh as a perfect example of territoriality in a polygamous species. The marsh is still there but no blackbirds. I would draw attention to the flight song of the ground-nesting Horned Lark. I can’t remember the last time I saw one. Fascinating was the sound of the “bullbat” as some people called the Common Nighthawk. Circling far above, the male would go into a dive and just before hitting the ground spread his wings to produce a booming sound. Haven’t seen one in years.
I could name more species but you get the idea. We bemoan the loss of individual birds and our diminished field trip lists, but let’s look at the gaps they leave in the ecological and economic world.
Birds are predators on all sorts of insects. “In New England they once thought blackbirds useless, and mischievous to the corn. They made efforts to destroy them. The consequence was, the blackbirds were diminished; but a kind of worm, which devoured their grass, and which the blackbirds used to feed on, increased prodigiously . … they wished again for their blackbirds.” -Benjamin Franklin, 1749.
Several bird species have been identified as predators of insect pests, eating as much as 400-500 million tons of insects a year. About 220 species of birds in North America eat invertebrate agricultural pests. In Australia small orchards were screened in to exclude birds; the crops were more damaged by pests than the orchards open to birds. During Mao’s revolution in China in the late 1950’s, farmers were encouraged to kill House and Tree Sparrows, which they did, in horrific numbers. A few years later famine followed on the heels of a major locust invasion on the crops.
Birds are important pollinators of wildflowers, especially hummingbirds in North America. In tropical regions birds like honeycreepers, honeyeaters, and sunbirds are critical for pollination of crops like papayas, nutmeg, and bananas. In some tropical forests, birds disperse up to 92 percent of all tree and woody species, including 85 timber species, 182 genera of edible plants, 153 medicinal plants, 146 ornamental plants, and 84 genera with other economic or cultural uses.
Vultures dispose of dead and decaying carcasses of wild animals as well as cattle, helping to limit the spread of disease and saving considerable money that would otherwise be spent disposing of the bodies.
And birds themselves are major economic drivers, generating perhaps $82 billion a year in North America from bird-watching related activities – travel, lodging, binoculars, and other gear. Researchers in Kenya estimated the annual value of flamingo viewing in Lake Nakuru National Park at $2.5 million to $5 million.
I could go on, but the point is that you can use these facts to convince non-birders that our feathered friends are well worth protecting for reasons other than the enjoyment of birdwatchers.