海角大神

Imagine being out in nature. Maybe you鈥檙e in a forest, or your backyard. The sun is shining and a light breeze blows through the trees. Perhaps a squirrel runs by. A hawk or gull soars overhead. Songbirds dart from tree to tree.

Now, remove a quarter of the birds. What changed?

That scenario isn鈥檛 a stretch of the imagination. That鈥檚 exactly what鈥檚 happened in the United States and Canada since 1970, according to a study published today in the journal Science. In just 48 years, bird populations have declined by 29%. That鈥檚 nearly 3 billion birds.聽

This is not the only staggering statistic about life on Earth. Just in the past year, there were reports that聽all insects might vanish within a century. In May, a United Nations biodiversity report warned that 1 million animal and plant species are at risk of extinction, many within decades. And now, it鈥檚 the birds.

Still, 鈥渋t鈥檚 kind of a proactive message,鈥� says Ken Rosenberg, lead author on the new study and applied conservation scientist at the Cornell Lab of Ornithology in Ithaca, New York. 鈥淲e鈥檙e seeing this loss, but we鈥檙e at the stage where it鈥檚 not too late to do something about it.鈥澛�

Indeed, one common reaction to these disquieting reports has often been a call to action. But the papers themselves represent a shift in how we think about nature under siege. Instead of focusing on individual species that are at risk of extinction, we鈥檙e beginning to zoom out and think about the state of life on Earth more broadly. And the way humans respond to those more global concerns may say something about our ability to leverage our species鈥� unique capacity for kinship and empathy.

鈥淪ome of these stories are depressing, but if they鈥檙e shifting people to notice something鈥� broader, says Jennifer Welchman, professor of philosophy and ethics at the University of Alberta, 鈥渢hey may do some real good.鈥�

Compelled to care

Three billion is a lot of birds to lose. And these aren鈥檛 a bunch of rare birds getting rarer. About 90% of those birds come from common, widespread families, like sparrows, warblers, finches, and swallows.聽

For the past several decades, campaigns to save wildlife have largely focused not on common creatures, but on the rarest. In the United States, the Endangered Species Act allots funding and efforts entirely to specific species that are under relatively immediate threat of extinction.

That framework has been successful at preventing extinction in many cases. But these new studies raise questions about what we value: Should we keep at least some of every species alive, or work to maintain populations of entire families of creatures?

Up until now, the threat of extinction 鈥撀爋f anything 鈥� has been a particularly compelling motivator.聽

鈥淚t鈥檚 so final,鈥� says Susan Clayton, professor of psychology and environmental studies at the College of Wooster in Ohio. 鈥淲e can feel bad about declining numbers of birds, but there鈥檚 always鈥� a chance they鈥檒l bounce back, or we can do something later. There鈥檚 a sense of urgency around the idea of extinction 鈥� 鈥渢hey鈥檙e just gone,鈥澛爏he says.

There鈥檚 also an element of empathy, says Dr. Welchman, that is built into how humans interact with other beings. Seeing others suffer 鈥渕akes us feel bad as well, in different ways, and want to relieve that suffering,鈥� she says, just 鈥渓ike we want to relieve suffering in ourselves.鈥�

So when humans can envision a specific animal suffering 鈥� like, say, a sea turtle with a plastic straw stuck in its nostril 鈥� it can be easier for them to connect with the animal鈥檚 pain and want to take action.聽

We know we have this capacity to empathize with an individual creature that we see suffering from a specific threat. But when talking about a group of species facing myriad threats, is it too difficult to connect with that unspecified pain?

It鈥檚 not just animals鈥� welfare at stake. Fewer of one creature can throw an entire ecosystem out of whack, which could have repercussions for agriculture, clean air and water, and other environmental factors we take for granted.聽

Humans鈥� sense of environmental stewardship can come from an obligation to future generations of humans, too, says Dr. Welchman. 鈥淭here鈥檚 this sense that we have that no one generation is entitled to claim to own the Earth,鈥� she says. 鈥淵ou shouldn鈥檛 destroy it and there shouldn鈥檛 be less of it when you鈥檙e done.鈥�

Seeing the flock

The dismal bird news likely doesn鈥檛 come as a huge surprise to birders and backyard bird-watchers.

Typically the spring migration is like Christmas morning to avid birders, says Jeffrey Gordon, president of the American Birding Association. But, he says, 鈥渢here鈥檚 less under the tree than there used to be.鈥澛�

The rest of us, however, may be forgiven for not noticing the decline. Sparrows and finches still flit about parks and yards. Pigeons and geese clutter urban paths. But 鈥減eople need to understand that they can鈥檛 trust that surface appearance,鈥� says Dr. Welchman.聽

This new paper may clue us in to the subtle but important differences in our environment, she says. For example, according to the paper, grassland bird populations have diminished by 53% (about 720 million birds) since 1970. Shorebirds have also lost more than a third of their population.聽

But there are some bright spots. Some raptors and waterfowl showed an increase in their populations, likely due to conservation efforts over the past several decades. Since DDT was banned as a pesticide, bald eagles and other majestic birds have rebounded. Duck hunters and others have invested in conservation of their prey to maintain stable populations for generations to come. Bluebird populations have increased thanks to nest boxes in homeowners鈥� yards and gardens.聽

There likely won鈥檛 be a silver bullet solution. The study did not examine causes of the decline, but habitat loss is likely to blame for much of it, says Dr. Rosenberg. We鈥檙e 鈥渟queezing nature out of the landscape,鈥� he says, between the growth of cities and suburbs, and the intensification of agriculture.聽

Still, there is hope, says Trevor Lloyd-Evans, director of the land-bird conservation program at the nonprofit Manomet in Plymouth, Massachusetts, pointing to successful efforts in the past. He says, 鈥淲e certainly have the capacity to make a difference.鈥�