Hummingbirds may look cute with their colorful plumage and those long, delicate beaks. But don't be fooled: a new study shows that male hummingbirds use those sharp beaks like swords, viciously stabbing rivals in the throat to keep them away from their ladies (see video above).
That makes the hummingbird the first bird known to use its bill as a weapon. What's more, the finding has ornithologists rethinking ideas about the evolution of the tiny birds.
"Historically, bird beaks have been the prime example of adaptation through natural selection, such as in the textbook example of Darwin’s finches,” lead author Dr. Alejandro Rico-Guevara, a research associate in the department of ecology and evolutionary biology at the University of Connecticut in Storrs, said in a written statement. “But we show here the first evidence that bills are also being shaped by sexual selection through male-male combat.”
For their research, Rico-Guevara and a colleague went to Costa Rica and spent four years studying long-billed hermits, a species of tropical hummingbird native to Central and South America. The researchers measured the length and sharpness of the beaks of both young and adult birds, and observed the birds in their natural habitat.
The researchers found that adult male birds had the longest, sharpest beaks and that the birds put them to use in "jousting" with rivals as part of a courtship ritual. And--no surprise here--the guys with the baddest beaks came out on top.
The findings suggest that the male birds' beak shape evolved in response to the birds' competition for mates. Previous theories held that the birds' beaks were an adaptation that allowed them to sip nectar from flowers. But now the evidence seems to suggest that the flowers evolved in response to the birds' long beaks.
The study was published online Oct. 18 in the journal Behavioral Ecology.