Have you ever looked up at the sky and seen birds wildly chasing after one another? This exhilarating display is more than just play. Bird chasing serves several important purposes that are key to avian survival.

If you want a quick answer, here’s the gist: birds chase each other to establish dominance, defend territory, attract mates, and protect their young.

In this comprehensive article, we’ll explore the nitty-gritty details on why birds engage in chasing behaviors. You’ll learn about the different types of bird chasing, the theories behind this phenomenon, and how it benefits birds in the wild.

Establishing Dominance Hierarchies

Dominance Displays

Birds have complex social structures and hierarchies that are reinforced through various dominance displays and behaviors. Many bird species establish a “pecking order” where more dominant birds have priority access to resources like food, nesting sites, and mates (1).

Dominant birds maintain their status through aggressive behaviors like chasing, pecking, crest raising, wing flashing, and vocalizations.

Some common dominance displays in birds include:

  • Puffing up feathers to appear larger
  • Spreading wings and tail
  • Raising crest feathers on the head
  • Charging at or chasing other birds
  • Pecking at other birds
  • Vocalizations like song, calls, and shrieks

These displays often happen more frequently at key times like breeding season when competition for mates is high. The most aggressive and persistent birds usually gain dominance. Once the hierarchy is established, aggressive displays are less necessary except to reinforce status (2).

Enforcing the Pecking Order

The pecking order is the social hierarchy that develops in groups of birds. The dominant alpha birds have priority access to resources while subordinate birds defer to those above them. The order is maintained through various dominance behaviors.

Some ways birds enforce the pecking order include:

  • Supplanting – A dominant bird displaces a subordinate from a desired spot like a nestbox or feeding area.
  • Chest Bumping – A dominant bird slams its chest into a subordinate bird to push it aside.
  • Chasing – Dominant birds chase subordinates away from contested areas.
  • Pecking – Aggressive pecks reinforce ranking, especially among chickens.
  • Posturing – Dominant birds may stand tall and spread wings over cowering subordinates.

The pecking order helps minimize overt fighting once established. However, challenges arise on occasion, especially from juvenile birds coming of age. This can lead to renewed chasing and pecking. Sometimes a subordinate may even defeat and replace a dominant bird (3).


(1) https://www.audubon.org/news/why-do-birds-sometimes-attack-each-other

(2) https://besjournals.onlinelibrary.wiley.com/doi/full/10.1002/pan3.10079

(3) https://www.sciencedaily.com/releases/2007/10/071009212548.htm

Territory Defense

Birds are highly territorial creatures, and they frequently chase other birds that encroach on areas they consider their own. Defending a territory is crucial for protecting vital resources like food, nesting sites, and mates.

According to research from the Cornell Lab of Ornithology, over 75% of North American bird species exhibit territorial behavior. Humans may view birds chasing each other as aggressive, but it is simply their instinct to secure their livelihood.

Protecting Resources

A bird’s territory contains resources essential to its survival and reproduction. These resources include:

  • Food sources like seeds, nectar, insects, fish, etc.
  • Nesting spots such as tree cavities, dense shrubs, ledges, etc.
  • Mates for breeding

Losing control over any of these could severely impact a bird’s fitness. Thus chased intruders pose a real threat. Interestingly, some tropical bird species even shrink their territories in years when resources are scarce.

According to a study, this allows them to conserve energy for defending the smaller space.

Warding Off Intruders

Birds identify territorial intruders through sight, sound and even smell. When an intruder is detected, resident birds start by issuing warning calls and displays. For example, a bird may spread its wings to appear larger or sing threatening songs.

If the trespasser doesn’t back off, the resident initiates a chase, sometimes with neighbors joining in. Most chases end when the intruder leaves the disputed area. But battles can turn physical too, with opponents grappling using their beaks and claws.

These fights determine which bird retains or takes over the territory.

Bird Species Territorial Behavior
American Robin Aggressively chases intruders, sometimes in groups of up to 20 robins mobbing an intruder.
Northern Cardinal Males attack other males entering their territory by pecking and clawing.

Territorial behavior certainly adds drama and excitement to the feathered world. Watching birds defend their turf can be an eye-opening lesson in resourcefulness for us humans too! Whether a dozen American robins mobbing a trespassing cat or two hummingbirds dueling mid-air over a flower bed, these tiny powerhouses put up a formidable fight for what is theirs.

Courtship and Mating

Impressing Potential Mates

Birds engage in elaborate courtship rituals to attract a mate. Male birds especially may put on colorful displays, sing complex songs, or perform interesting dances to show off to nearby females. These rituals serve to demonstrate that the male is healthy and has good genes to pass on to potential offspring.

For instance, a male frigatebird will puff out his red throat pouch to astonishing proportions to wow a female. Peacocks are well known for their ostentatious plumage used to impress peahens. Bowerbirds create entire structural works of art adorned with colorful objects to lure female admirers.

Birds are willing to go to great lengths to secure a high quality mate with which to breed.

Fending Off Rivals

Mated birds often chase off intruders to defend their territory or nesting area. Unmated males may also chase rivals who try to encroach on their courtship displays. Aggressive high-speed aerial pursuits where birds lock talons and peck or claw at each other sometimes erupt as they competitively vie for mating privileges and breeding resources.

Fiercely chasing away challengers illustrates a bird’s strength and dedication to mating and potential offspring. However, such dangerous fights can result in injury or even death in extreme cases. But for birds, the reward of passing on genes is often worth these risks and shows the deep evolutionary drive to reproduce.

Defending the Nest

Chasing Predators

Birds can become very territorial and aggressive when defending their nests and young from predators. They will chase, dive-bomb, and even physically attack animals or other birds that get too close to their nest.

This mobbing behavior is an attempt to scare predators away by acting aggressive and putting themselves in harm’s way.

Some common nest predators that parent birds may chase away include cats, snakes, raccoons, squirrels, crows, jays, and hawks. Small songbirds will band together with other birds to mob predators that are too large for a single bird to fend off.

Diving at a predator’s head and pecking at them can disorient them and signal that the nest area is well-defended.

This nest protection usually happens during the breeding season when eggs and chicks are most vulnerable. Parent birds will be on high alert and quick to chase anything that seems threatening. The more intense and prolonged the mobbing, the greater the perceived threat to the nestlings.

Once the chicks are grown and leave the nest, this territorial behavior decreases.

Driving Away Brood Parasites

Some birds, like cuckoos and cowbirds, don’t build nests of their own – instead they lay their eggs in the nests of other species in a behavior called brood parasitism. However, many host birds have evolved ways to fight back against these freeloading intruders.

Birds can recognize foreign eggs and remove them from the nest. If an adult brood parasite comes near the nest, the defensive parents may chase them away or even peck at them to prevent more unwanted eggs from being laid.

Some birds have learned to build domed nests with small entrances, making it harder for the parasites to access their nest and lay eggs.

Researchers found thatYellow Warblers aggressively mobbed and chased Brown-headed Cowbirds away from their nests. As a result, only 5% of the warbler nests were parasitized, compared to 20-40% parasitism rates for warblers that did not attack cowbirds (a study by University of Michigan).

So by aggressively chasing the brood parasites, the warblers helped ensure the eggs and nestlings they were raising were their own.


Bird chasing allows avians to establish social hierarchies, defend precious resources, attract the best mates, and protect their offspring – all behaviors critical to survival. The next time you witness birds partaking in dramatic chase sequences across the sky, remember that these actions have deeper meaning and purpose in the avian world.

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