Swedish and Indian researchers on a trip to the Himalayas of northeastern India noticed that brown birds that were believed to belong to the same species were actually singing different songs.
Those living in the forests or lowlands had a sweet, melodious song. But the ones in the rocky highlands above the treeline had a much harsher, scratchier melody.
The scientists wondered if the birds — known as the plain-backed thrush — were actually two different species. If this were the case, it would be an exciting discovery because only three new species of birds had been found in India since 1949.
The effort to solve the avian mystery eventually led the scientists — Per Alström and Shashank Dalvi — to the University of Michigan Museum of Zoology, home to one of the largest collections of bird specimens in the U.S.