When a flock of crows began attacking an owl in my neighborhood, I heard a commotion a few blocks away. It was late afternoon, when the owls were supposed to be sleeping.
Dozens of crows flocked to the owl as it moved from tree branch to roof to fence post. The owl, old and missing an eye, seemed ready for any approach from the crows.
The crow is the enemy of the owl. Mass aggressionOver the past 50 years, more scientists have become interested in studying schooling behaviour, which they say can be an important defense against predators.
What is bird mobbing behavior?
Pack aggression typically occurs when prey perceive a predator to be dangerously close; the prey cooperate to attack the predator and drive it out of its territory. Pack aggression can also occur among other species, including mammals.
Aggression is usually accompanied by both vocalizations and physical postures. For example, crows make loud cawing noises that serve to warn other crows to join in, and the noise may also confuse and alarm the target. Physical postures include chasing, swooping, and pecking.
read more: Why do animals fight? And what do they fight for?
Which birds are known to attack in groups?
(Credit: Karen Burgess/Shutterstock)
Birds that attack in groups are common in backyards across the country. Blue jays, black-capped chickadees, crows and mockingbirds are some examples of birds that attack predators in groups.
“I think it happens more often than we realize. We have to learn to recognize the sound.” Holly ShortHe is the shorebird program manager for Audubon Florida in St. Petersburg.
Mobbing is not a typical bird call and sounds more like a cawing or angry chirp.
“I have blue jays in my yard, and you can hear them calling when they sense a predator,” Short said. “They’re trying to chase that hawk off their territory.”
Flocks of birds typically attack predators like hawks and owls in groups, and while some birds will swarm to attack anything that threatens their nests or territories (including humans who get too close), other birds, like crows and mockingbirds, are more cognitive and will target known threats, Short said.
When a flock of birds attacks a predator, different species may cooperate to attack the target.
“When birds like crows and jays start to sing, if you watch and listen, you’ll see other birds joining in,” Short says. “In these instances, I’ve seen cardinals, red-bellied woodpeckers and tufted titmice begin to sing.”
Attacking in packs can also attract the attention of other species that could fall prey to the predators.
“I’ve seen squirrels respond to these calls and flocking behaviors by coming out to see what’s going on,” Short says, “and perch on a branch and watch the hawks being flocked by the birds.”
read more: Why do some people like watching animals fight each other?
The benefits and risks of mobbing
The advantage of mobbing is that dozens of birds can work together to drive predators from a territory, which helps protect young, but can also leave nests vulnerable to attack.
Nests can be left unattended while the flock is busy hunting predators — in Florida, when little terns attack crows, they put chicks and eggs at risk from opportunistic predators, Short said.
“Even if the birds are flocking together, it’s not actually the birds that are in danger from the crows, so it’s dangerous,” Short says. “Crows don’t attack adults, but [the least terns] The colony is left abandoned because of the mob gathering there.”
Mobbing There may be a riskSo too would a much larger predator fight back. Flocking behaviour requires a lot of energy, and scientists have observed seasonal effects, with birds less likely to flock together in winter when resources are scarce.
read more: Why do bird eggs come in different colors?
Can birds attack humans?
(Credit: Jen Oswald/Shutterstock)
Birds will swarm anything that threatens their territory, especially if they believe their young are in danger. For example, black skimmers are black-and-white shorebirds with orange legs and orange-and-tan beaks. But these beautiful birds will swarm and attack beachgoers who wander too close to their nests.
Wildlife officials often set up signs and ropes to keep people away from nests, and Short cautions people to take such warnings seriously.
“We tell people to be careful of the ropes and the nests. You want to make sure you don’t step on anything, but at the same time, you don’t want to get swarmed,” she said.
read more: These birds learn to recognize people they don’t like
How long will the mobbing last?
The collective attacks will continue for as long as necessary, “until the threat moves out of the area and is no longer a threat,” Short said.
For example, a human who happens upon a black skimmer’s nest will likely flee the area quickly, but a predator may not flee when the flock begins to raid – it may need to rest, or it may try to raid the nest again or attack the adults.
Mass attacks offer a short-term solution to eradicate potential threats, and scientists don’t know at this point whether predators will learn that certain areas or groups are off-limits after a shocking mass attack.
And, of course, the researchers don’t know whether other wildlife, like the squirrels Short watched as they attacked in droves, would be happy to see a predator chased off their territory.
read more: What is a cassowary? It may be the most dangerous bird in the world
article source
Our writers Discover Magazine Our articles use peer-reviewed research and high-quality sources, and our editors review them for scientific accuracy and editorial standards. Please check out the following sources used in this article:
Emily Lucchesi has written for some of the nation’s largest newspapers, including The New York Times, The Chicago Tribune, and The Los Angeles Times. She holds a BA in Journalism from the University of Missouri and an MA from DePaul University. She also holds a PhD in Communication from the University of Illinois at Chicago, where she specialized in media framing, message construction, and stigma communication. Emily has written three non-fiction books. Her third, A Light in the Dark: Surviving More Than Ted Bundy, co-written with survivor Cathy Kleiner Rubin, will be published by Chicago Review Press on October 3, 2023.
