Solar: Anywhere from about 1,000 birds a year, according to BrightSource, to 28,000 birds a year, according to an expert at the Center for Biological Diversity.
Wind: Between 140,000 and 328,000 birds a year in the contiguous United States, according to a December 2013 study published in the journal Biological Conservation. Taller turbines tend to take out more birds.
Oil and Gas: An estimated 500,000 to 1 million birds a year are killed in oil fields, the Bureau of Land Management said in a December 2012 memo.
Coal: Huge numbers of birds, roughly 7.9 million, may be killed by coal, according to analysis by Benjamin K. Sovacool, director of the Danish Center for Energy Technologies. His estimate, however, included everything from mining to production and climate change, which together amounted to about five birds per gigawatt-hour of energy generated by coal.
Nuclear: About 330,000 birds, by Sovacool’s calculations.
Power Lines: Between 12 and 64 million birds a year are felled by transmission lines, according to a study published July 3 in the journal PLOS ONE.