Apr 25, 2022 I Paul Seaburn

How Crows and Ravens Took Over the World

Poe gave them a voice. Hitchcock gave them a starring role. The British gave them their own keeper and apocalyptic power. We’re referring, of course, to ravens and crows – whose ‘caws’ are the cause of fear in farmers protecting precocious crops, hikers on a moonlit night and movie patrons waiting for something to emerge from the grounds of a cemetery. A new study reveals a new aspect of crows and ravens, who are already recognized for their intelligence, tool use and problem-solving abilities – their diversity. How did these large black birds manage to migrate to so many continents and thrive in so many different climate zones?

“When we think about processes of global diversification, it is important to consider not just the ability to reach new places, but also the ability to survive once you get there. Our work suggests that crows and the ravens diversified both quickly and widely because they were particularly good at coping with different habitats.”

Carlos Botero, assistant professor of biology in Arts & Sciences at Washington University in St. Louis and co-author of a new study published in the journal Nature Communications, explains in a university press release how, while their big brains and big intelligence helped, the real reason crows and ravens seem to be everywhere is their unique ability to go with the flow and make minor changes when needed. Lead author Joan Garcia-Porta, a former postdoctoral research associate at the university, pinpoints three specific traits which make crows and ravens better at coping than other species and even the jays and magpies in their own class of Corvids.

  • ·         Longer wing lengths
  • ·         Bigger body sizes
  • ·         Bigger relative brain sizes
Did you hear that? Bigger brain sizes!

At first glance, these traits seem obvious – yet this is the first study to peg them to the worldwide spread of crows and ravens. Of course a bird needs long wings to fly long distances, yet no other long-flying birds show up in as many museum collections around the world than crows and ravens. Once the black birds arrived in a new location, their larger body sizes gave them a competitive advantage over smaller local species in the quest for food and nesting areas. However, it’s that big brain which took advantage of those other abilities and tweaked both the mental and physical design of crows and ravens to make the changes that boosted them into the top tier of birds wherever they landed.

“These new environments often favor tweaks to an organism’s phenotype that facilitate survival and overall performance. That process is often known as optimizing selection.”

According to Botero, the most significant tweak crows and raven brains made to their bodies was a new beak design. These two renegade Corvids don’t have the same beaks as their jay and magpie cousins – and the evolution happened almost overnight.

“In terms of beak shape, crows and ravens not only reproduced many of the shapes already present in their family but also evolved entirely new beak types in short time periods (e.g., Corvus crassirostris and Corvus moneduloides). Because these morphological traits have a well-established adaptive basis, our findings suggest that the global radiation of crows and ravens cannot merely be understood as the result of dispersal and (non-adaptive) allopatric speciation, but also of considerable adaptive divergence driven by ecological factors.”

It is an impressive beak.

Changes in beak design allowed crows and ravens to adapt to new foods, fight new enemies and breath in new climates. That last trait explains why they have such a high rate of island colonization in the Corvid family – crows and ravens are found in Hawaii (3800 km or 2361 miles from the mainland), Guam and New Zealand. It is on these remote islands where the researchers found the most diversity in beak sizes.

“Because colonization success is often limited by ecological factors, these findings suggest that crows were able to colonize the entire globe very quickly not only because they had an exceptional capacity to reach distant locations but also a remarkable ability to persist in suboptimal environments and adapt quickly to new conditions.”

Sir Paul McCartney may have been wrong in the advice he gave in a popular song by Wings: if this ever changin' world In which we're livin' makes you give in and cry, don’t live and let die – live like a crow or a raven … make rapid changes, adapt and cope.

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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