Something I have noticed quite a lot when out and about is birds of prey, usually buzzards, being attacked by crows. I am surprised at this because surely a bird of prey could easily take out a lesser bird if they chose to, but they never seem to retaliate. Why would crows even take the risk?
This common behaviour is known as ‘mobbing’. It is a defensive tactic in response to a perceived threat by predators, such as buzzards and red kites. Crows have few, if any natural predators but they are known to be fiercely territorial and will aggressively defend their themselves and their young.
What is Mobbing?
Mobbing is just how it sounds – crows will take to the skies to outnumber and bully another bird they identify as a threat. They will persistently invade the predator’s airspace, aggressively chasing it until it leaves their territory. Typical mobbing behaviour includes dive bombing, loud squawking, defecating.
This mobbing behaviour will usually involve a number of crows but it is not unusual to see just one or two in pursuit of the subject. A precursor to mobbing is crows becoming very restless and noisy in their habitat. This is a warning signal both to each other and the buzzard or other predatory bird. It has been said that if you want to spot a bird of prey, listen to and watch the crows first.
When Do Crows Mob a Buzzard?
Mobbing is more common around breeding time, as crows will be nesting and raising their young. It is then the threat of harm is at its greatest. It is a learned behaviour, passed down through the generations, with younger birds watching their parents defending them. This calculated risk serves a few purposes:
- Annoy a predator enough that it moves on
- Serves as a warning to other colonies nearby, that a predator is near
- It distracts the predator enough that it fails to find its prey – a young crow or a nest
Why Don’t Buzzards Attack The Crows?
It is surprising to see these magnificent and powerful birds of prey simply putting up with these lesser birds’ aggression. However, despite the sheer power and weaponry of a buzzard, a more peaceful and less harmful outcome is preferable to the risk of a physical conflict.
If a buzzard chose to attack, the crow would not last very long!
Although a buzzard would easily win a game of Top Trumps with its size, power and kill score, most would opt for an easy life and go elsewhere in this situation. There has been some research on this subject and, although relating to red-tailed hawks, the theory is likely the same for buzzards and other birds of prey.
Whit Gibbons is a herpetologist and Professor Emeritus of Ecology and former Head of the Environmental Outreach and Education program at the Savannah River Ecology Laboratory (SREL) University of Georgia. He wrote a post on this very subject. In his 2011 he reached out to a number of ornithologists to find out why it is that hawks do not fight back.
It turns out that the common theory among experts in this field is that the energy exerted by a raptor attempting to catch a crow is simply not worth it. Crows are agile birds and not easily caught. It is much easier to leave them alone, ignore them or go elsewhere. (source)
Why Do Crows Risk Mobbing Buzzards?
The crows will be doing all they can to protect their domain and their young from predators, whether that be a buzzard or other bird or animal. Mobbing is trait or behaviour crows have adapted over many generations – driving predators from an area where they raise their young to prevent them from becoming prey.
The risk is often worth it for the crows. An example is when a buzzard is not wanted in that space, nor does it really have any interest in staying. If a buzzard has already fed and is not looking for another meal at that time, the predator has no particular interest or investment in that area. So any bullying tactics from crows would not be worth the effort, to hang around for no real purpose. The buzzard will soon move away to hunt elsewhere. Make no mistake though, if a buzzard chose to attack, any crow would not last very long! (source)
What Other Birds Use Mobbing?
Crows are not the only birds to use mobbing against threats. Birds that breed in colonies such as gulls are often seen to display the same behaviour when a bird of prey strays too close to a colony. This usually happens near to the coast, where gulls normally nest. In the UK, as well as the US, the birds most frequently engaging in mobbing include:
The Difference Between Raptors vs Corvids
Buzzards are raptors. Raptors are birds of prey and include species of bird whose primary prey is vertebrates, often quite large relative to the hunter. They have very good eyesight for hunting from a distance, strong talons and powerful, curved beaks for ripping apart the flesh of their prey.
Crows are corvids. They belong to the Corvidae species of bird. There are over 120 species of corvid; the most recognisable are rooks, crows, jackdaws, ravens and magpies. Corvids are intelligent birds for their size; they are some of the most intelligent birds studied so far. Corvids have demonstrated an ability to make tools, often used to reach food skills previously thought to only be possessed by humans and a few other mammals.
Although it is quite obvious which would win in a fight, here is a quick comparison across the board.
|Countryside and woodland
|Fields, orchards, suburbs
|113 – 128
|93 – 104
|500 – 1400
|370 – 650
|51 – 57
|45 – 47
|Top Speed (mph)
|Small mammals, birds, carrion
|Insects, fruit, carrion
|12 – 20
|6 – 10