One does not expect to discover a bird species new to science while wandering around the continental United States. Nor does one expect that such a species would provide much insight into how coevolutionary arms races promote speciation. On both fronts a paper to appear in The American Naturalist proves otherwise.
Julie Smith, now at Pacific Lutheran University, and her former graduate advisor, Craig Benkman at the University of Wyoming, have uncovered strong evidence that coevolution has led to the formation of a species of bird new to science in the continental United States. Benkman discovered in 1996 what appears to be a new species restricted to two small mountain ranges in southern Idaho (the South Hills and Albion Mountains). This species is a morphologically and vocally distinct “call type” of red crossbill (Loxia curvirostra complex), which is a group of seed-eating finches specialized for extracting seeds from conifer cones.