The delicate beaks seen on hummingbirds could be used for more than just sipping nectar; new research suggests they can double as a deadly weapon.
The study provides the first evidence of weapons in male bills, and could provide insight into the evolution of the seemingly-peaceful birds, UConn reported.
"Historically, bird beaks have been the prime example of adaptation through natural selection, such as in the textbook example of Darwin's finches," said Alejandro Rico-Guevara, research associate in the Department of Ecology and Evolutionary Biology and lead researcher on the study. "But we show here the first evidence that bills are also being shaped by sexual selection through male-male combat. It is exciting to think of all these forces working on the way animals look, and to think about how they might affect males and females differently."
The recent study focuses on the long-billed hermit, which is native to Costa Rica. Once a female enters a male's territory he will court her through physical displays, and these bachelor males are in constant competition for the best territories. Researchers have long-known the male and female birds have differently shaped beaks, but thought it was because they fed on different flowers.
"The previous explanation of ecological causation suggested that males and females had different bill shapes because they fed on different flowers, perhaps to minimize competition between the sexes," said Rico-Guevara.
To make their findings the researchers measured the size and puncture capability of beak tips in juvenile and adult hummingbirds and found that during the birds' transition to adulthood males developed elongated beak tips that were sharper than what was seen in females. They also observed the male birds attempting to stab each other in the throat during fights, and found the males with longer and sharper bills were more likely to win battles and hold the most desirable territory.
"I think people initially think of them as beautiful, delicate creatures ... but I enjoy revealing their pugnacious attitudes," said Rico-Guevara.
The findings were published in a recent edition of the journal Behavioral Ecology.
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