In Solar Discussion, There Are Birds and Then There Are Birds

No one would lump these mammals together, so why do we do it with birds? | Photos: Martin Heywood (mouse, on left), Jim Frost (rhino, right) /Flickr/Creative Commons License

As part of the recent flurry of interest in the issue of harm to birds from solar power plants, some people are trying to compare the damage done to bird populations by solar facilities to other sources of bird mortality. If a coal plant kills more birds than a solar power plant, goes the reasoning, then the birds killed by a solar plant might be a reasonable cost to pay for getting off coal.

There's some truth to the argument. Fossil fueled power plants do an extraordinary amount of damage to the environment and wildlife, and sometimes trade-offs are reasonable to reduce the overall level of damage to the planet's other species.

But the discussion as it's shaping up on blogs and in social media is seriously flawed for a number of reasons. The biggest one: when it comes to gauging environmental harm, "birds" is a nearly useless category.

We covered this topic a year and a half ago in the context of wind turbine bird mortalities, but one of the arguments in that piece could use a little updating.

Say you're a person passionately concerned about African wildlife, and in particular the plight of the white rhino, and you're talking to a friend about the threat to that magnificent animal from illegal poaching. "It's a shame," replies your friend, "but you know, domestic cats kill far more mammals."

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You'd likely look at your friend as if he'd lost his mind. Who would lump a house mouse into the same category as a rhino just because they both fit into the taxonomic order of "mammals"?

No one, that's who. There is a huge amount of diversity among mammals, performing wildly different ecological roles on the planet. Some are painfully rare; others far too abundant. With more than 5,400 species of mammals diverse enough that taxonomists have divided them among 153 distinct families, it seems foolish to lump rhino mortalities and rat mortalities into the same ecological category. And it is.

Birds are far more diverse than mammals. There are somewhere in the neighborhood of 10,000 bird species, assigned to 225 families -- 72 more families than mammals have. The class Aves (birds) includes ostriches and eagles and hummingbirds, penguins and parrots, each of those groups as different from one another as opossums, tigers, and the mammals that build solar power plants.

Sometimes that diversity doesn't jump up and announce itself. To the non-ornithologist, the tinamou might seem more or less indistinguishable from a domestic chicken. But the common ancestor of both birds almost certainly died back in the Cretaceous period, more than 64 million years ago. They're about as unrelated as they can be and both still be birds.

We're just not used to seeing diversity in birds. Mammals are familiar, and so we notice differences more readily. There seems a huge difference between cats and dogs, for instance. But cats and dogs are pretty closely related compared to, say, eagles and house sparrows, and the ecological functions they fulfill are much more similar than those of the eagle and sparrow as well.

A recent offer by the owners of the proposed Palen Solar Electric Generating System to mitigate bird deaths at the plant by funding feral cat spay and neuter programs takes advantage of our willingness to assume all birds are the same. Spaying and neutering feral cats is a fine and noble act, but it helps protect a whole different set of bird species than stand to be injured at desert solar power plants.

For instance: a flock of native white pelicans was seen this summer at Lake Tamarisk, not far from where Palen would be built and within cruising distance of several other solar power plants, existing or proposed. Losing one white pelican to injury at a solar facility would be a shame. Losing ten thousand invasive starlings in Los Angeles to feral cat predation in the same week would be markedly unpleasant for the birds, but would likely be an environmental boon to native species.

Were someone to say in the wake of that very bad week for starlings that L.A. cats had killed ten thousand times as many birds as the solar plant did in the same period, it might sound like a profound observation. But it would reveal nothing. How many pigeons equal a California condor? How many house finches equals a Yuma clapper rail?

While we don't have nearly the kind of rigorously collected data on bird mortality at solar facilities that would allow us to assess those facilities' actual impact on wildlife, and more on that in a moment, there are some disturbing hints in the information we do have:

  • It's possible that due to their siting, desert solar plants may be harming a higher percentage of species of conservation concern than is true of urban buildings, suburban cats, or some of the other mortality sources being pointed at these days.
  • While the recent discussion has focused on the admittedly dramatic prospect of birds bursting into flame over solar power tower sites, other desert solar power plants also pose risks to birds of conservation concern, especially migrating birds who mistake several square miles of solar panels for a body of water. Mortalities of this kind have lately included two Yuma clapper rails, an Endangered species we can't really spare two of.
  • If the U.S. Fish and Wildlife Services' suspicion is correct that solar power tower plants may act as "ecological megatraps," attracting insects which attract insect-eating birds which attract bird-eating birds, then the important thing isn't so much numbers of carcasses as whether the plant is depleting an entire local food chain.
  • Many of the birds found dead at the Ivanpah plant this last spring are species that migrate long distances. Some fly between winter and summer ranges in Central America and the Arctic. Significant mortalities of these species during migration can thus have impacts across half a continent.

Comparing avian mortality at solar facilities with avian mortality from other sources without accounting for diversity among birds is neither good science nor good policy. It's persuasive only to people unfamiliar with basic biology, and it does nothing to make such people more familiar with the subject.

In any event, as we discussed last week, we simply do not have good numbers on how many individual birds or other flying wildlife are injured by utility-scale solar power plants.

We'll probably never have a precise count, but we could have a lot more accurate numbers than we do now.

At present, most of what we know about bird mortalities on solar plant grounds is compiled by biological consulting firms hired by plant operators. Those firms vary in their willingness to deliver bad news to their clients. ReWire has talked off the record to more than a few field biologists who have been informed at one point or another during their careers that reporting too many mortalities could cost them their jobs.

In order to know the true scope of damage these plants and others are doing to our wildlife, we will need resolve from state and federal agencies to compel solar companies to allow independent biological surveys of solar plants' entire footprints. Those surveys will need to take place at regular and frequent intervals, over the course of several years, and cover at least a majority of the plants' huge footprints.

While it would be reasonable to have the solar companies pay for these surveys as a cost of doing business, they should have no role in selecting the consulting firms or hiring individual biologists. Those biologists should work without restrictive non-disclosure agreements, and the results should promptly be made publicly available.

Otherwise, we'll just be comparing eagles and orioles.

For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.

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