Why Do Little Birds Chase Hawks?

Little birds chasing hawks (or other large birds and mammals) is known as mobbing. Mobbing is a defensive act that small birds use to drive off unwanted predators to protect themselves and their territories.

You’ve likely looked out your window or have been outside and noticed one or maybe many little birds harassing a larger bird. There is something to be said about this underdog behavior of small birds joining forces to drive off a larger bird, but what exactly is happening here?

What is Mobbing?

This behavior is called mobbing. Mobbing is an aggressive or defensive act by a group of small birds toward a larger bird. This group effort is usually made to protect nests with young, breeding grounds, food sources, and natural home territories.

Classic Behavior

Classic mobbing behavior is akin to calling in your friends and family for backup. There is generally a lot of fuss and noise. The cacophony of birds is helpful for two reasons.

1) To call for help. It is a lot like a bird 911, sending out the signal that reinforcement is necessary.

2) The loud noise is distracting to the large bird being disoriented and may confuse them.

Beyond loud cries, the small birds will swoop at and dive bomb the larger bird, causing a physical threat meant to drive the target off. Some birds, such as gulls and terns, will also defecate and vomit on their target.

Reasons For Mobbing

Mobbing is thought to be an activity purely based on protection. Prey birds use mobbing to keep their home territories safe from raptors and larger nuisance birds. Breeds such as grackles, crows, blackbirds, kingbirds, chickadees, and titmice all take part in mobbing for the reasons listed below.

1) Protection of Nests and Young

Hawks and other birds of prey are carnivorous, meaning they eat meat. Carnivorous birds will hunt for fish, mice, rats, and other small vertebrates. They also will eat small birds, their young, and their eggs.

Small birds have many behaviors to protect their nests from predation. In a dramatic display, the female killdeer will fake injury to lure predators away from their nests. But most small birds resort to the other effective means of mobbing.

2) Protection of Breeding Territory

Mobbing is a method small birds employ in the spring to protect their breeding grounds. To ensure that each species has a healthy clutch of eggs, it is essential to drive out predators and reduce the stress on the flock.

3) Protection of Natural Home Range

Mobbing is also used to keep the natural home range of small birds peaceful and safe. To eat, sleep and breed effectively, small birds need to feel safe. Using mobbing techniques helps establish a safety zone in the home territory of small birds.

4) Protection of Food Sources

Small birds require a massive amount of calories. For example, a hummingbird burns six to twelve thousand calories a day, just living life. This example shows how crucial safe food sources are for small birds. Mobbing behavior used to defend food sources ensures that birds will have adequate calories to remain healthy.

Common Mobbing Targets

While mostly all large raptors or birds of prey are targets for mobbing behavior, there are a few that are relentlessly targeted, likely for their disruptive and destructive behavior.

Hawks

As a large bird of prey, hawks eat mice and squirrels and small to midsize birds. Small species of birds can sense the danger that is present when encountering a bird of prey.

Mobbing is one of the techniques used against hawks routinely as they try to encroach on smaller birds’ territory either to eat the small birds’ young or even the mature bird.

Owls

Though there are owl species that are day waking, many are nocturnal. This poses a severe threat to species of small, diurnal birds (awake during the day).

Mobbing has been used to ensure these birds can protect themselves and their young and the sleep that their bodies require to maintain health. But mobbing owls does not always go to plan.

Owls are one species that may benefit from mobbing. By listening to the sounds to discern the whereabouts of his distractors, the owl can then turn to hunt mode and easily pick the small birds off.

Ravens

Ravens are not immune from being harassed by little birds, but the bulk of the mobbing attention they receive comes from crows.

There seems to be a lifelong grudge between these two birds. The raven is the larger of the two and is also a more solitary animal. The smaller crow is much more social and can adopt a “pack” mentality.

For this reason, crows will regularly mob ravens over competition for food or territory. Crows will take an aggressive approach towards ravens, frequently dive-bombing them. If mid-flight, a raven will certainly pivot and try to avoid danger, though if perched, the raven will usually ignore the spectacle and carry on with what it was doing, knowing no actual harm will come to it.

Mobbing as a Physical Display Rather Than Protection

Once thought to be a solely protective measure, it is now understood that mobbing can also be used as a mechanism for male birds to display their physical attributes, thus making them more attractive to mates.

In particular, males of the lyrebird species have used mobbing not to show off their physical prowess but to scare female lyrebirds into mating, a type of doomsday approach.

Strength in Numbers

Though small in stature, various small birds display great strength when joining forces to protect what they find valuable. Mobbing is found in many species, not only birds, but birds are undoubtedly the most visible mobbers.

The next time you witness birds partaking in aerial acrobatics, you may be more inclined to figure out if it is mobbing. If so, who is being mobbed, and by what? Happy birdwatching!

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