Bird Deaths Continue Through May at Ivanpah Solar

Recorded bird deaths at the Ivanpah Solar Electric Generating System ebbed only slightly in May after their peak in April, and more than half the bird carcasses reported to the state energy agency showed signs of injury from the plant's concentrated solar energy.

According to the Monthly Compliance Report for May filed with the California Energy Commission (CEC), a total of 80 birds were confirmed killed at the San Bernardino County solar plant in May. 44 of the birds showed clear signs of scorching, singeing, or melting of feathers consistent with exposure to extreme temperatures, as would happen if the birds flew through the plant's solar flux fields.

Solar flux burns weren't just recorded on the birds' sensitive feathers. Several of the carcasses were described as having had burns to the skin beneath the feathers. Two birds, both barn swallows, were described as showing injuries to their eyes consistent with solar flux injuries, and one of the two swallows had burns on his cloacal protuberance -- an organ roughly equivalent to the mammalian scrotum.

The report also listed two dead bats, a Mexican free-tailed bat and a California Myotis, found on May 3 and 4 respectively.

The 392-megawatt ISEGS, formally online since February, generates power by focusing sunlight on boilers atop three 459-foot towers using tens of thousands of mirrored heliostats. That concentrated solar energy emerged as a concern for wildlife safety during CEC hearings on other projects proposed by ISEGS designer BrightSource Energy, and will play an important role in a final decision on the similar but larger Palen Solar Electric Generating System proposed for Riverside County.

ReWire often receives comments on our monitoring of wildlife deaths at Ivanpah to the effect of "80 isn't very many compared to the birds killed by cats, windows, or the number that will be killed due to climate change." We address arguments like that in some detail here. But it's important to remember that the animal mortalities listed for Ivanpah in each month's Compliance Report are almost certainly a drastic undercount.

Of the 80 bird carcasses recorded in May, 55 were found during carcass surveys while the remaining 25 were "incidental" finds made by plant workers during normal work operations. As only about 20 percent of the facility is covered by the carcass surveys, it's reasonable to assume the actual month's death toll is upward of 300 or so.

Factors that might hide additional deaths include the lack of any surveys outside the plants' perimeter fences, despite observers having seen injured birds make it past the fence.

There's also the fact that ISEGS is apparently home to a growing population of desert kit foxes, with five active dens as of April apparently housing at least nine months-old pups. It's hard to imagine an animal better suited to scouring a project site for small dead animals before the biologists can find them than adult desert kit foxes working to feed a litter, and the foxes' presence means the official dead bird tally is almost certainly lower than the actual death toll.

And given that solar power tower technology's advocates seek to build many more such plants, the 80 bird deaths documented in May's Monthly Compliance Report at Ivanpah take on a significance well beyond their own admittedly moderate numbers. To use a jarringly fractured metaphor for the California desert, these deaths are likely the tip of the iceberg, and there are those who advocate bringing a lot more such icebergs online.

The May death toll at ISEGS included the kinds of species we've been seeing turn up in previous Ivanpah compliance reports, with small insectivorous birds extremely well represented in the roster. Mourning doves led the death toll at nine birds, most of whom seemed to have died in collisions with the mirrored heliostats, with the remainder being made up of swallows, sparrows, and warblers, and other small birds likely to follow clouds of insects attracted by the glowing solar flux fields.

Two apparently new species appeared in May's roster: two lazuli buntings, strikingly colored birds common throughout open lands in the West that catch small insects in flight, and a Lapland longspur, a small songbird generally found in the Arctic in late May instead of the California desert. In fact, Lapland longspurs are rare enough in California at any time of year that range maps for the species generally exclude most of the state, as well as Nevada.

More so than in past months' Compliance Reports, the descriptions of the injuries suffered by the dead birds are rather affecting. Take for instance the record of an unidentifiable hummingbird found on May 6:

Or a Costa's hummingbird found May 2, of which the biologist simply wrote "most of tail burnt off."

Or a mourning dove found on May 9: "Large amount of flight and body feathers found in a ~20 ft diameter scattered all around a heliostat."

If that kind of imagery doesn't kick you right in the cloacal protuberance we don't know what will.