A new study undertaken by Alejandro Rico-Guevara, from the Department of Ecology and Evolutionary Biology at the University of Connecticut, and Marcelo Araya-Salas, from the New Mexico State University, has reached a groundbreaking new conclusion.
Hummingbirds use beaks as weapons
Instead of beaks displaying variations because of the different flowers fed on by males and females, the duo concluded that the males also use their longer, sharper beaks as a weapon in duels over females.
It was Rico-Guevara who first observed the use of the beaks as a weapon, and began an investigation in conjunction with Araya-Salas into the beaks themselves. The first point of interest is that adolescent males develop elongated beak tips which are sharper than their female counterparts.
The hummingbird mating ritual includes a phenomenon known as leks, where male hummingbirds battle for space in order to mate with a female. Research showed that those with longer, pointier beaks had a greater chance of winning these battles.
“Once a female is in a territory, the male will court her with elaborate displays and songs. So in these species the males are constantly fighting to maintain the best territories,” Rico-Guevara said.
Revising the relationship between beaks and flowers
The research also offers a different interpretation on the evolution of the flowers on which the hummingbirds feed. Until now it was believed that the hummingbird evolved beaks which best fitted the shape of the flowers. However this new research suggests that the flowers in fact evolved to fit the shape of the hummingbird beak.
“Our study provides the first evidence of sexually dimorphic weapons in bird bills and stands as one of the few examples of male weaponry in birds,” said the researchers. “Our results suggest a role of sexual selection on the evolution of overall bill morphology, an alternative hypothesis to the prevailing “ecological causation” explanation for bill sexual dimorphism in hummingbirds.”
The full study was published in the journal Behavioral Ecology on October 18.