Crows are highly intelligent birds that exhibit complex social behaviors. One interesting behavior that has been observed in some crow species is the act of mobbing potential threats in an apparent effort to warn others of danger. But do crows truly understand the threats they mob and intentionally warn others, or are they simply responding instinctively to dangerous stimuli?
What is mobbing behavior in crows?
Mobbing refers to when crows gather together and harass or attack a potential predator or other perceived threat. They may dive-bomb the intruder, call loudly, or recruit other crows to the area. This mobbing behavior seems to serve two purposes:
- To drive the potential threat away from the area
- To alert other crows to the presence of danger
Mobbing is thought to be an innate, instinctive behavior in many bird species. It is often observed in crows, jays, magpies, and other highly social corvids. The more crows join in the mobbing, the more intensely they attack the predator. There is safety in numbers, so gathering together against a threat likely evolved to increase survival.
Do crows understand dangers and intentionally warn others?
There is some evidence that crows don’t just mob predators mindlessly based on instinct, but they actually recognize and remember specific dangers and call other crows to warn them. Here are some key findings:
- Crows have been shown to make different alarm calls for different threats, suggesting they distinguish between types of dangers.
- Crows can recognize individual human faces and appear to identify particular people as threats based on previous negative experiences.
- Crows will mob specific people identified as dangers while ignoring neutral people.
- When hearing alarm calls, crows will look for the specific threat they are being warned about.
These behaviors suggest that mobbing in crows is not just an instinctive reaction, but an intentional cooperative behavior to alert others in their group to danger. Crows don’t just blindly join mobs, they evaluate threats and spread targeted warnings.
Crows distinguish between types of threats
Research has shown that crows produce different alarm calls for different kinds of threats, such as different predator species. This implies they recognize variances in the types of dangers.
| Threat | Call Type |
|---|---|
| Hawk | short, low calls |
| Owl | longer, higher pitched calls |
| Dangerous person | harsh, rasping calls |
The ability to distinguish threats and produce threat-specific warning calls suggests an intelligence beyond simple instinctive reaction. The crows must be capable of correctly identifying the danger and intentionally signaling to others about the specific type of threat.
Crows recognize dangerous people
In an experiment by University of Washington researchers, individual crows were captured, tagged, and released. The crows remembered the faces of the specific people who had captured them and scolded them with alarm calls on subsequent encounters. They did not alarm call at people who were present when captured but had not handled them. This demonstrates an ability to recognize individual humans as specific threats based on learned experiences.
Crows warn others about familiar threats
A study in France provided further evidence that crows transmit information about specific dangers to other crows. Researchers placed a taxidermic mount of a hawk in one location that wild crows encountered and mobbed. Later, at a different location without the hawk, they played a recording of the crows’ alarm calls for that hawk. Naive crows that had never seen the hawk looked up and scanned the sky for a long time after, as if searching for the hawk in response to the calls. The researchers concluded the crows were transmitting information about the specific, familiar threat.
How do crows communicate danger?
Research shows crows have a complex language of vocalizations they use to communicate information about threats. Here are some of the things we know so far about how crows warn each other:
- Alarm calls – Harsh, noisy calls communicate presence of immediate danger and recruit others to mob.
- Roost gatherings – Crows gather at night to sleep/socialize and may share information on threats.
- Mobbing – Loudly mobbing a threat together transmits danger information.
- Non-vocal signs – Diving, swooping motions draw attention to a threat location.
- Mimicry – Some crows copy calls of predators to alert to that type of threat.
Additionally, adult crows appear to teach young crows about threats and how to mob predators. Their communication is not just instinctive, but a learned, cultural behavior transmitted between generations.
Alarm calls
When discovering a potential threat, crows will immediately emit loud alarm calls to warn others. These alarm calls tend to be harsh and high-pitched. The alarm calling quickly recruits other crows to mob the intruder.
Roost gatherings
Crows roost together at night in large communal groups. Researchers believe information about threats may be shared at these roost gatherings. This would allow them to warn the wider murder (group) of crows about dangers beyond their immediate social circles.
Mobbing
By loudly mobbing a threat together, crows transmit information that this is a danger warranting alarm. Naive crows see the mobbing and learn that this is a situation requiring caution.
Non-vocal signaling
Crows may use non-vocal signals like diving at a threat to draw attention and communicate danger. These action-based signals complement the vocal alarm calls.
Mimicry
There is evidence that some crows mimic the calls of predators to specifically warn of that type of threat. Just as they have different alarm calls for hawks vs. owls, mimicking a hawk call alerts others to that particular kind of danger.
How do crows identify dangers?
Crows have excellent observational and learning abilities that allow them to recognize threats. Intelligent corvids have demonstrated the ability to:
- Rapidly learn to differentiate dangerous people from neutral ones
- Read facial expressions to determine if a person is a threat
- Recognize dangerous animals, objects, or situations
- Retain vivid memories of negative experiences
- Teach young crows about known threats
Additionally, evolutionary instinct equips crows with innate wariness of stimulus attributes associated with predators, such as rapid approach, direct gaze, and outstretched arms. Mobbing anything with these features keeps crows safely on the side of caution.
Observation and learning
Crows are incredibly observant and fast learners. They can rapidly learn to identify which people have harmed or posed a danger to them in the past based on facial recognition. They then respond to these dangerous people through scolding and mobbing.
Reading expressions
Studies show crows have the intelligence to read human facial expressions and determine whether a person is likely to be threatening or neutral based on emotional expressions.
Recognizing threats
Crows appear capable of recognizing as threats any animals, objects, or situations that have harmed them or their kin in the past. For example, crows recognize and remember individual hawks that have killed other crows.
Retaining memories
Crows have incredible memories, allowing them to retain vivid recollections of negative experiences and identify dangers from their past. Captive crows have been shown to remember individual human faces for over 5 years.
Social learning
Juvenile crows are taught by adult crows how to identify threats through mobbing behavior. By mimicking their parents’ mobbing of predators, young crows learn which animals are dangerous.
Innate wariness
Crows instinctively mob anything approaching quickly, staring at them directly, or reaching towards them. These are all attributes of predators, so crows innately perceive them as potentially threatening.
How do crows benefit from warning others?
Warning others of danger is clearly beneficial to crows’ survival as a species. There are several key advantages provided by actively alerting their social group about threats:
- Deters predators – Mobbing may drive predators from the area, making it safer.
- Safety in numbers – More crows harassing a threat together can better deter it.
- Shared vigilance – Warning others allows the group to be on alert and vigilant together.
- Better defense – Recruiting others to mob improves defensive capabilities.
- Social learning – Juveniles learn defensive behaviors through mobbing.
- Bonding – Shared mobbing reinforces social bonds and group cohesion.
Actively warning others about specific dangers clearly provides crows advantages in defending themselves, avoiding predation, and learning as a group. It is a strategy that enhances the entire colony’s coordination, defense, and chances of survival against threats.
Deters predators
Loudly mobbing predators may drive them away from nesting or feeding areas, making the area safer for the crows by deterring the threat.
Safety in numbers
There is strength in numbers when mobbing a predator. The more crows harassing the threat together, the more intense and effective the bombardment will be in driving it away.
Shared vigilance
Informing others allows the entire murder of crows to be alert and on watch for the signaled danger together. Shared vigilance is more effective than individual vigilance.
Better defense
Recruiting other crows to mob an intruder means there will be more birds available to harass, distract, and confuse the predator. This improves defensive capabilities.
Social learning
When juvenile crows observe and join mobbing events, they learn to recognize predators as dangers and acquire mobbing behaviors through social learning.
Bonding
Shared mobbing helps reinforce social bonds between crows by promoting cooperative behaviors that benefit the entire group.
Do other birds warn about threats?
Yes, mobbing behavior and threat-signaling is seen in many highly intelligent bird species beyond crows. Other birds observed using alarm calls or mobbing to warn others about threats include:
| Bird | Behavior |
|---|---|
| Chickadees | Mob predators and produce warning calls |
| Ravens | Recurit others to mob via loud calls |
| Magpie | Alarm call to signal hawk threats |
| Blue jays | Mob predators and give “thief” alarm calls |
Mobbing and threat signaling has clear evolutionary benefits by allowing information about dangers to spread quickly through social groups. Any intelligent, social species is likely to evolve adaptations to communicate threats to others.
Conclusion
In summary, extensive research shows that crows don’t simply mob predators mindlessly. They possess the intelligence to recognize and remember specific threats, and purposefully communicate information about dangers to other crows through vocalizations, actions, and social learning. Warning others of threats provides crows evolutionary advantages in defending themselves, deterring predators, and learning as a group. Mobbing and threat signaling behaviors extend beyond crows to many intelligent bird species. So when you hear crows loudly mobbing in the trees, rest assured they likely have good reason to be scolding!
