Looking up into the sky, you see a big, majestic bird of prey being hounded by several other smaller birds. What is going on here? This is the bird equivalent of you or I chasing down a lion so why do little birds attack big birds?
Little birds will attack big birds to drive them away from their nesting areas. This behavior is called mobbing. They will also do this to alert other birds to the danger or perhaps to teach their young how to recognize a predator. It may also be done simply to chase a predator from their territory.
It is not just other birds that smaller birds will attack either. Continue reading to find out what other predators little birds will attack. We will also explore whether the little birds or the predators ever get injured or even killed in these mobbing incidents.
What Little Bird Species Will Attack Bigger Birds?
Mobbing behavior has been observed in many different bird species, from titmice to crows. Here in Australia, it occurs in small birds such as the Superb Fairy Wren (14cm or 5.5″), all the way up to larger birds such as the Sulphur-crested Cockatoo which is not a small bird at all at around 44-55cm (17.5″ to 21.5″) long.
In the video below a Sulphur-crested Cockatoo chases a monitor lizard from trees, even grabbing hold of it and throwing it to the ground?! It’s getting some help from some Noisy Miners that are flying about screeching also; most likely at the lizard and the cockatoo:
Little Wrens Fight Back
Superb Fairy Wrens, one of Australia’s most beautiful little birds will mob Cuckoos (slightly larger than they are) who are known to be brood parasites. This means they never build their own nests or raise their own young.
While the wrens are absent from the nest, a cuckoo will sneakily replace one of its eggs with one of its own. Cuckoo eggs look very similar to those of the fairywrens so the wrens are none-the-wiser. A cuckoo chick even looks and sounds like a fairy-wren chick so the poor wrens are fooled right up until the infiltrator leaves the nest.
Superb Fairy Wrens will mob cuckoos that come close to their nesting area in an attempt to chase them off. They are obviously aware of their devious behavior on some level.
Perhaps the most common mobsters in Australia are Noisy Miners.
These plentiful birds do pretty much everything they do in groups. They are aggressive towards all other species of birds and each other. They can often be seen uniting to chase a much larger predator away from their territory.
Are These Birds Crazy?
Attacking a predator that is much larger than you and would most likely enjoy eating you seems like a dumb thing to do. When you think about how predators normally attack, however, it’s not as dumb as it seems.
Predators rely on the element of surprise when catching prey. Their most important weapon is stealth. When your prey has keen eyesight, good hearing, and wings it mustn’t see you coming.
If these smaller birds can see the predator before it sees them and gang up on it they can successfully chase it from their territory. The element of surprise is taken away from the larger bird, making it nearly impossible for it to catch or harm the smaller birds.
Does this mean that the little birds are never harmed or killed during the mobbing? Unfortunately not always…
When Mobbing Goes Wrong
Though mobbing does employ the “safety in numbers” theory and foils the predator by taking away their element of surprise, sometimes things go wrong.
During my research for this article, I came across a thread on birdforum.net in which someone describes seeing Javan Mynahs mobbing a White-bellied Sea Eagle in Singapore.
The eagle took a few pecks to the head before flipping over and grabbing one of the mynahs. It then proceeded to bite the wings off it and then started eating the body of the mynah as it flew on.
Another person in the same thread reported seeing a Red Kite taking a Crow that had been harassing it. He also mentioned that this was the third sighting of this behavior in North Leeds at the time.
So the attackers sometimes become the victims. What about the predators? Do they ever get injured or killed?
Do Mobbing Birds Ever Kill The Predator?
There is no evidence of a bird of prey or any larger bird being killed by mobbing birds, at least none that I could find. They do however get injured.
In the same forum thread from above, one man reports seeing a group of ravens mobbing around a grounded bald eagle. They attacked it repeatedly, pulling out most of its tail feathers before it finally had enough and took off.
One comment in that same thread makes me think that perhaps the predators do get killed on occasion. It may be that no one has yet seen it happen.
Fernando np commented that he had once seen six ravens attack a Montagu’s Harrier while it was bathing. The ravens repeatedly attacked the harrier in what seemed to be an organized strike rather than a mobbing. They coordinated their attack with two ravens keeping the harrier from flying to any decent height while the others attacked it.
This man was convinced the harrier would have been killed had he not intervened by yelling and throwing stones to give the harrier a chance to escape.
Will Little Birds Ever Mob Other Predators?
Owls, Hawks, Eagles, and other large predatory birds are not the only victims of mobbing. As you saw in the video above, other animals such as lizards sometimes fall victim to it as well.
Birds will often attack snakes as well to scare them away from their nesting areas. This driveway camera footage from KHOU 11 shows some small birds taking on a snake that has come into their territory in Georgia:
The Australian Magpie Attacks
Ask any Australian about birds that attack things and they will probably say something that includes the words “bloody Magpies?!”
The Australian Magpie has a notorious reputation for dive-bombing people during the Spring breeding season. They will go after a person relentlessly until they are driven, often screaming and crying, from their territory.
This unfortunate little boy in this 7News Australia footage knows the tenacious mobbing behavior of magpies all too well:
I have had my own experiences with magpies too. I once ended up with a nice little hole in the top of my head when pecked by one when I was about 7 or 8 years old.
This behavior is what causes a lot of misguided hatred for magpies in Australia. The birds are merely trying to protect their young from what they view as a dangerous predator.
I think we should be awestruck by the bravery and the unshakeable maternal instincts of these and other birds. The lengths they will go to to protect their young are simply incredible.
- Mobbing – The National Audubon Society North American birdfeeder handbook, Rober Burton
- Mobbing – Encyclopedia of birds, Derek Hall
- Mobbing birds killed – birdforum.net
- Fairy-wrens learn fast how to mob cuckoos – ABC Science