Crows start bird fights with ravens 97% of the time

When crows and ravens fight, it’s the smaller crows being the aggressor about 97% of the time. It may be them being protective of their nest or it may be competition, but ravens are the ones being bullied.

Don’t mess with crows. They’re intense.
Don’t mess with crows. They’re intense. (Credit: Sunny Ripert)

The more we learning about crows, the more intriguing they get. It’s not enough to learn they use tools. It’s not enough that they reward kindness with gifts. And it’s not enough that they remember faces and can hold a grudge. Now, it turns out, they’re on a mission to keep ravens in their place. Never mind that ravens are the larger Corvus. Crows are in charge.


The insight comes from the analysis by University of British Columbia’s Benjamin G. Freeman and Cornell University’s Eliot T. Miller of 2,014 reports submitted by citizen scientists across North America.

(Credit: Freeman/Miller)

Not picking on someone their own size

Crows, it turns out, were the aggressors in about 97% of all the hostile interactions. The researchers were able to sort 1,704 of the reports into one of three categories for both crows and ravens:

  • Strength in numbers—where the number of aggressors was greater than the number of those attacked.
  • Fair fight—where aggressors and the attacked were roughly equal in number.
  • Outnumbered—where the aggressors were clearly outnumbered by the birds they attacked.

(Credit: Freeman/Miller/BigThink)

Remembering that crows are smaller than ravens, it makes sense that they most frequently dominated ravens by “mobbing” them. There were very few instances of crows going after a greater number of ravens, though there were a few courageous exceptions, particularly during nesting season, as it turns out.

Why are crows being so aggressive?

One of the data points researchers tracked was the seasonality of the aggression. While crows attacked ravens all year round, they did so especially from March to May, which is crow nesting season, and also during late autumn.

(Credit: Freeman/Miller)

Step away from the nursery

Ravens have been witnessed pillaging crow nests, and the researchers suspect that the uptick in springtime attacks represents crows fending off predators from their vulnerable young. Crows communally tend their chicks and it’s easy to imagine the rapid gathering of a mob in response to an incursion by ravens. Ravens, the study notes, are two to three times heavier than crows and far more often a threat to crow chicks than the other way around, though crows do also predate other birds’ nests.

(Credit: Freeman/Miller)

Without wishing to anthropomorphize, the fact that crows are more likely to resort to fair fights and outnumbered attacks during the breeding months may suggest a protective intensity on their part. In the late-autumn attacks, they’re more likely to mob their targets. It could also be that with more mouths to feed in the spring, competition for resources is especially compelling, though the researchers favor the first explanation.


Carrion crows nest .(Credit: NottsExMiner)

Winter’s coming

The rise in aggressive behavior in late autumn is a bit of a mystery, though the researchers say, “We speculate that territoriality may be important to explaining why crows attack ravens in winter, either due to resource competition or because crows take a proactive approach to deterring nest predators for the upcoming breeding season.”

This latter point seems especially plausible when talking about crows, given their known ability to hold grudges. And given their demonstrated intelligence, the authors wonder if some of their aggressiveness derives from a shrewd long-term strategy: "Future studies should investigate whether frequent crow attacks affect the spatial use or abundance of ravens; that is, whether crows may actually constrain raven populations.”

Fascinating birds.

‘Designer baby’ book trilogy explores the moral dilemmas humans may soon create

How would the ability to genetically customize children change society? Sci-fi author Eugene Clark explores the future on our horizon in Volume I of the "Genetic Pressure" series.

Surprising Science
  • A new sci-fi book series called "Genetic Pressure" explores the scientific and moral implications of a world with a burgeoning designer baby industry.
  • It's currently illegal to implant genetically edited human embryos in most nations, but designer babies may someday become widespread.
  • While gene-editing technology could help humans eliminate genetic diseases, some in the scientific community fear it may also usher in a new era of eugenics.
Keep reading Show less

There are 5 eras in the universe's lifecycle. Right now, we're in the second era.

Astronomers find these five chapters to be a handy way of conceiving the universe's incredibly long lifespan.

Image based on logarithmic maps of the Universe put together by Princeton University researchers, and images produced by NASA based on observations made by their telescopes and roving spacecraft

Image source: Pablo Carlos Budassi
Surprising Science
  • We're in the middle, or thereabouts, of the universe's Stelliferous era.
  • If you think there's a lot going on out there now, the first era's drama makes things these days look pretty calm.
  • Scientists attempt to understand the past and present by bringing together the last couple of centuries' major schools of thought.
Keep reading Show less

Astrophysicists find unique "hot Jupiter" planet without clouds

A unique exoplanet without clouds or haze was found by astrophysicists from Harvard and Smithsonian.

Illustration of WASP-62b, the Jupiter-like planet without clouds or haze in its atmosphere.

Credit: M. Weiss/Center for Astrophysics | Harvard & Smithsonian
Surprising Science
  • Astronomers from Harvard and Smithsonian find a very rare "hot Jupiter" exoplanet without clouds or haze.
  • Such planets were formed differently from others and offer unique research opportunities.
  • Only one other such exoplanet was found previously.
Keep reading Show less

Lair of giant predator worms from 20 million years ago found

Scientists discover burrows of giant predator worms that lived on the seafloor 20 million years ago.

Bobbit worm (Eunice aphroditois)

Credit: Rickard Zerpe / Flickr
Surprising Science
  • Scientists in Taiwan find the lair of giant predator worms that inhabited the seafloor 20 million years ago.
  • The worm is possibly related to the modern bobbit worm (Eunice aphroditois).
  • The creatures can reach several meters in length and famously ambush their pray.
Keep reading Show less
Politics & Current Affairs

FOSTA-SESTA: Have controversial sex trafficking acts done more harm than good?

The idea behind the law was simple: make it more difficult for online sex traffickers to find victims.

Scroll down to load more…
Quantcast