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These Hummingbirds' Bills Evolved for Fighting — a hummingbird hovering over a purple flower

These Hummingbirds' Bills Evolved for FightingCEFR B1

25 Nov 2025

Adapted from U. Washington, Futurity CC BY 4.0

Photo by Skyler Ewing, Unsplash

AI-assisted adaptation of the original article, simplified for language learners.

Hummingbirds are known for their fighting, but male green hermit hummingbirds have evolved unique bills for this purpose. These birds live in mountain forests in Central and South America and gather to compete for mates.

Research from the University of Washington shows that male green hermit bills are straighter and sharper than those of females. This design helps them fight effectively for mates, while females have curved bills to access nectar more easily.

Further studies revealed that male bills are both structurally stronger and more efficient during fights. Their improved design results in less energy loss in combat, allowing them to fight with greater ease. This phenomenon demonstrates the influence of fighting behavior on physical evolution in birds.

Difficult words

  • evolveTo change over time to adapt or improve.
    evolved
  • billThe beak of a bird used to eat or fight.
    bills
  • competeTo try to win against others for something.
  • structurallyRelated to the way something is built.
  • phenomenonAn observable event or fact.

Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.

Discussion questions

  • What do you think about the role of evolution in animal behavior?
  • How do you feel about the competition among animals for mates?
  • Can you think of other examples where physical traits help in survival?

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