A Bird of Two Colors

Related to shearwaters and petrels, the Northern Fulmar will eat just about anything it finds on the surface of the ocean, from fish and squids to dead whales. While some have snow-white bodies and gray wings, others are dark gray all over. That’s because fulmars are polymorphic, which is to say they come in multiple colors or “morphs.” The difference is genetic and doesn’t depend on age, sex, or season. This color variation may offer behavioral or habitat-based advantages to fulmars and other polymorphic species like Snow Geese, screech-owls, or Red-tailed Hawks.

BirdNote^®
Birds Of Two Colors
Adapted from a script by Dennis Paulson

This is BirdNote.

[Wind whistling; sound of boat engine]

Sail miles off the coast in the North Pacific Ocean and you’ll find birds you’d rarely see from shore.

[Northern Fulmar calls]

Like this Northern Fulmar, an abundant seabird related to shearwaters and petrels. Fulmars have long wings, stocky bodies, and thick bills. But, wait! Some of these fulmars look like gulls, with snow-white bodies and gray wings, but others are dark gray all over. What’s that about?

[Northern Fulmar calls]

Northern Fulmars are a color polymorphic species, which is to say they come in multiple colors or morphs. The difference is genetic and doesn’t depend on age, sex, or season. And while breeding colonies tend to be dominated by birds of one color morph, fulmars readily form mixed-morph pairs.

Color variations aren’t unique to fulmars and may offer a species behavioral or habitat-based advantages. But genetic studies show that this trait tends to accelerate the evolution of new species.

[Northern Fulmar calls]

Perhaps in watching these dual-toned birds forage and fraternize, we’re seeing evolution play out in real time? It’s something to ponder — to keep your mind off seasickness — while out in the realm of the fulmar.

[Wind and waves]

For BirdNote, I’m Michael Stein.
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Senior Producer: Mark Bramhill
Producer: Sam Johnson
Managing Producer: Jazzi Johnson
Managing Producer: Ariana Remmel
Content Director: Jonese Franklin

Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Northern Fulmar recorded by W.W.H. Gunn. Ambient waves and boat motor by Kessler Productions.
BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.
© 2026 BirdNote February 2010 & October 2026
Narrator: Michael Stein

ID# NOFU-01b-2010-02-06 NOFU-01b

Reference:
https://www.nature.com/articles/nature11050
https://www.allaboutbirds.org/guide/Northern_Fulmar/id