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For some birds like hermit hummingbirds, the difference between sexes starts with the beak. Females hermit hummingbirds typically have curved bills while males wield straighter ones. Because the two sexes are better at drinking nectar from flowers that match their respective beak shape, males and females of the same species don’t compete with each other for food resources. Adaptations like these can provide benefits for the whole species.
BirdNote®
Different Beaks, Different Foods
Written by Conor Gearin
This is BirdNote.
[Northern Cardinal song, ML339922801]
In some bird species, males and females look pretty different — for example, male Northern Cardinals are bright red, and females are mostly brown. In some species, the differences between sexes even help them eat different foods.
[Rufous-breasted Hermit calls, ML535855781, 0:39-0:41]
In the group of hummingbird species called hermit hummingbirds found in Central and South America, females typically have curved bills, while males have straighter ones. This makes the females better at drinking nectar from flowers with curved bases, while males visit flowers with straight bases. This could help males and females avoid directly competing for the same flowers.
[Hispaniolan Woodpecker calls, ML181975211, 0:03-0:06]
The Hispaniolan Woodpecker from Haiti and the Dominican Republic also divvies up food resources based on bill size. In this species, males have the bigger bills. They spend more time pecking at bark and probing deep tree holes. Females usually pick at insects and spiders on the surface of leaves and bark. Both the females and males are capable of the same types of feeding — it’s a difference in emphasis and how they spend their time.
Adaptations like these help birds share space with each other. Avoiding competition has benefits for the whole species.
For BirdNote, I’m Michael Stein.
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Producer: Mark Bramhill
Managing Editor: Jazzi Johnson
Managing Producer: Conor Gearin
Content Director: Jonese Franklin
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Northern Cardinal ML339922801 recorded by Matt Wistrand, Rufous-breasted Hermit ML535855781 recorded by Benjamin Hack, and Hispaniolan Woodpecker ML181975211 recorded by Jay McGowan.
BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.
© 2025 BirdNote January 2025
Narrator: Michael Stein
ID# bill-08-2025-01-13 bill-08
Reference:
Evolution of sexual dimorphism in bill size and shape of hermit hummingbirds (Phaethornithinae): a role for ecological causation
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2830232/
Hispaniolan Woodpecker (Melanerpes striatus)
https://birdsoftheworld.org/bow/species/hiswoo1/cur/introduction?login#food