Our Biomass Crisis: The Avian Edition

Long before the Cool Kidz were saying it, I’ve been warning that we have a biomass crisis:

When is the last time, in those habitats, you have seen enough fish (and minnow-sized fish don’t count) to justify this strategy? What many people don’t realize is that these habitats, until a couple of centuries ago were teeming with wildlife; in terms of productivity, these habitats are marine equivalent of Iowa farm soil. In Maine, lobster, in shallow habitats, were so plentiful, they were used to fertilize soil–and feeding lobster to servants, slaves or orphans in the 1600s was illegal (it was considered feeding people cockroaches). Ditto the fish.

Needless to say, we’ve changed those environments. Despite those changes, it’s safe to say these habitats and most of their species still exist, though many species have probably altered their behavior and physiology to compensate for human activity (e.g., cod reproduce at smaller sizes to produce offspring before being caught). On the other hand, there are habitats that we have essentially annihilated, such as the pre-European American prairie. The passenger pigeon is extinct, and the bison is a relict species.

Whether or not coral reefs will become extinct doesn’t seem to be the right question. The real issue is one of massive alteration: are a decrease in coral reef size, altering of animals (e.g., cod), and the loss of biodiversity–locally on reefs and globally by species extinction–acceptable? Will (or how many) species go the way of the bison or passenger pigeon? Will coral reef ecosystems be confined to small isolated, habitat islands? And is this good for us?

And:

No one alive truly understands what we have done to oceans–that they could be so teeming with life is completely alien. There simply isn’t any place where one can find this concentration of marine organisms (unless you’re in the middle of a school of fish). We have created a barren desert.

In other words, we are converting non-human associated biomass into human-associated biomass, such as agricultural systems (meat and plant) and, of course, people. Which brings us to our feathered friendly dinosaurs (boldface mine):

A new study, which analyzed decades of data on North American birds, estimates that the continent’s bird populations have fallen by 29 percent since 1970. That’s almost 3 billion fewer individuals than there used to be, five decades ago. “It’s a staggering result,” says Kenneth Rosenberg from Cornell University and the American Bird Conservancy, who led the analysis.

“This is a critically important study,” says Nicole Michel, an ecologist at the National Audubon Society. Past work has shown that specific groups of birds are declining, but this is the first study to rigorously put a number on the full extent of these losses. And surprisingly, it shows that the most ubiquitous birds have been the hardest hit. “The common wisdom was that we’d see the rare and threatened species disappearing and the common, human-adapted ones taking over,” Rosenberg says. Instead, his team found that 90 percent of the missing birds came from just 12 families, and that they were all familiar, perchy, cheepy things such as sparrows, warblers, blackbirds, finches, larks, starlings, and swallows…

With this great emptying of the skies, there are now 3 billion fewer beaks to snap up insects, and 3 billion fewer pairs of wings for moving nutrients, pollen, and seeds through the world. We haven’t just lost birds, but all the things that birds do, “as well as our connection to what is arguably one of the most widely cherished forms of wildlife on the planet,” says Kristen Ruegg from Colorado State University. “Our forests and backyards will continue to grow quieter with every passing year, and within that leftover space there is an opportunity for complacency about the natural world to grow.”

The causes aren’t nailed down at this point, but likely include habitat loss (due to farming and housing), cat predation (most likely the largest source of mortality), and collisions with human structures.

It’s not that these animals are going extinct. It’s that when populations crater, especially larger populations, that quantitative change becomes a qualitative change. The ecosystem is simply not what it once was. And this has happened during my lifetime.

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2 Responses to Our Biomass Crisis: The Avian Edition

  1. Bern says:

    The ending of nature was a nasty business…

  2. Ron Zoscak says:

    Why are you blaming cats? Don’t you think the decline in the insect population might have something to do with it?

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