Crows are large, intelligent birds that are found all over the world. They have glossy black feathers and large, powerful bills that they use for eating a variety of foods. Crows are very social birds that gather in large flocks called murders. Despite their large size and intimidating appearance, crows are sometimes attacked and harassed by much smaller birds. There are several reasons why this occurs.
Territorial Behavior
One of the main reasons small birds attack crows is to defend their territory. Birds are highly territorial animals and will aggressively chase away intruders. Crows have large territories and will often fly into the turf of smaller birds like chickadees, titmice, and nuthatches. These little birds will band together and mob the crow, diving at it, calling loudly, and pecking at it until it leaves the area. Small birds do not actually cause any harm to the much larger crow, but their harassment is often enough to drive the crow away.
Protection of Nest and Young
In addition to defending their general territory, small birds are especially aggressive towards crows during nesting season. Many species like robins, mockingbirds, and song sparrows will attack crows that get too close to their nest. This mobbing behavior is an attempt to drive the crow away from the vulnerable eggs and nestlings. Crows sometimes raid the nests of smaller birds for eggs and chicks so the little birds are extra defensive of their nest sites when crows are around.
Defense Against Predators
While crows do not usually hunt small songbirds for food, they will at times raid nests for eggs and chicks. Smaller birds seem to be aware of the predatory threat that crows can potentially pose. Harassing crows that get near their territories or nests may be an evolved defense mechanism to protect against predation. Constantly driving crows away establishes dominance over them and reduces the chance that the crows will try to raid nests in that area. Even though the crows do not have killing the smaller birds in mind, mobbing them teaches the crows that the area is off limits.
Competition for Resources
Crows and smaller bird species often compete for the same food resources. Crows are omnivores and eat a wide variety of foods including seeds, fruits, nuts, small vertebrates, invertebrates, and even garbage. Their diverse diet means they feed on many of the same energy sources that smaller birds rely on. Plentiful food sources attract foraging crows which then monopolize the food and leave less for other birds in the area. The smaller birds may attack crows to try to preserve the food source for themselves and their young.
Distraction from Nests
There is some evidence that small birds may mob crows even when their nests are not nearby. This harassment may function as a distraction to shift the crows’ attention away from a hidden nest in a different location. Essentially the small birds are sacrificing themselves by attracting the unwanted attention of the crows. While the crows are being chased away in one direction, they are not exploring other areas where offspring may be vulnerable to their nest raiding.
Bird Species | Body Length (cm) | Wingspan (cm) |
---|---|---|
American Crow | 40-50 | 84-100 |
Black-capped Chickadee | 12-15 | 18-22 |
Tufted Titmouse | 16-18 | 23-26 |
Size Difference Between Crows and Small Birds
Part of the reason that small birds are so bold in attacking crows is that crows do not pose a mortal danger to them. There is a huge size difference between crows and the small passerines that typically mob them. To illustrate this, the table compares the body lengths and wingspans of crows versus two species that commonly pester them – chickadees and titmice. Even though crows are much larger, they are not equipped to seriously injure the tiny but tenacious little birds.
How Small Birds Attack Crows
When attacking crows, small birds engage in mobbing behavior. Mobbing is a harassment technique where a number of birds will simultaneously dive bomb, chase, and scold a predator or other intruder. Different species join together to form mixed flocks for these mobbing forays. The most common small birds that attack crows include:
Chickadees
With their small bodies, big heads, and even bigger attitudes, chickadees are among the most aggressive crow harassers. They will furiously scold crows with their loud chickadee-dee-dee calls. Flocks of several chickadees will pursue crows through the trees while diving at them repeatedly.
Titmouse
Similar in size and shape to chickadees, titmice are also eager attackers. Their sharp pik calls pierce the air as they chase crows through territory boundaries or away from nest sites. Tufted titmice and black-crested titmice are among the titmouse species that help drive off crows.
Nuthatches
Though they move headfirst down tree trunks, nuthatches switch to upward forays when mobbing crows. With short tails and compact bodies, white-breasted and red-breasted nuthatches make persistent if somewhat comical attackers. Their nasal yank-yank calls follow crows as they harry them through the forest canopy.
Blue Jays
While they sometimes fall prey to crows, as fellow corvids blue jays are eager to turn the tables and give crows a hard time. Their loud, raucous alarm calls alert other birds to the crows’ presence. Jays chase and dive bomb crows with their bold blue and white plumage flashing.
Blackbirds
Red-winged blackbirds and grackles may forgo their usual groundfeeding behavior to flutter up into trees and join mobbing efforts. Taking advantage of their greater numbers, blackbirds will overwhelm crows and see them on their way.
Song Sparrows
Though small and brown, song sparrows have fierce tempers when defending their nests. Their buzzing trills accompany them as they harry crows near nesting sites. Other sparrow species like white-throated sparrows may join in driving the crows away.
Crow Response
Crows do not passively accept the mobbing they receive from other birds. Here are some of the ways crows react to being dive bombed and scolded by flocks of smaller birds:
Retreat
Crows often choose to retreat from the harassment rather than escalate a confrontation. Being intelligent birds, they seem to realize the small birds pose them no real threat. Crows will casually fly or hop away while emitting low rattles and chuckles, almost as if laughing off the attacks.
Fight Back
At times, crows stand their ground and physically defend themselves instead of retreating. They may spread their wings and tails to appear more intimidating to their tiny attackers. Crows have been observed striking back at small birds with their stout bills and sometimes grabbing them briefly in retaliation before letting them go unharmed. Their counterattacks are measured though, meant to communicate annoyance rather than cause injury.
Enlist Other Crows
If one crow is severely outnumbered by a large mobbing force, it may call for backup. The distinctive caws of a crow under siege will summon other crows to the area. The arrival of more crows evens the odds and often causes the small birds to disperse. There is strength in numbers, even if the crows don’t intend to seriously fight the small birds.
Wait It Out
At times, crows simply wait for the whirlwind of feathers and furor to die down. Perched calmly, they withstand repeated dive-bombing stoically. Given that the smaller birds cannot actually damage the crows, just the crow’s presence in the area is often enough to accomplish their goals like repelling territorial intruders. The crows seem to realize this and do not feel compelled to quickly leave if they have reason to be in the area.
Why Small Birds Are So Aggressive Towards Crows
The fact that tiny songbirds just a fraction of a crow’s size will boldly attack them begs the question – why are they so aggressive? Here are some of the key factors that drive small birds to mob crows despite the size disadvantage:
Territoriality
Many birds are fiercely territorial and view any encroachment as a threat. Unlike humans who have boundaries marked with fences and walls, birds must defend invisible turf boundaries vigorously. Allowing crows to move through their space would set an unwanted precedent.
Nest Protection
The reproductive drive is strong, and adult birds will risk their own safety to protect eggs and chicks. Though crows do not always raid nests, the small birds likely evolved mobbing behavior because crows posed a historical threat. It is better to be safe than sorry when your offspring are involved.
Predator Defense
Small birds have an ingrained wariness of larger birds like crows due to their predatory potential. Harassing them triggers an anti-predator response. The attacks function as a preemptive defense to ensure their own survival.
Food Competition
Because crows are omnivores, they compete with smaller birds for identical food sources. Allowing crows to feed freely could leave less seeds, fruits, and invertebrates for the smaller species. Aggression functions to make the crows move on so the smaller birds and their offspring have enough to eat.
Strength in Numbers
By banding together, small birds can amplify their harassment and make it more difficult for crows to remain. Even though individuals are tiny, as a coordinated mob they become a formidable opponent capable of driving off much larger crows. There is safety in numbers when deterring potential predators.
Distraction Strategy
Mobbing may serve to distract crows from locating nests in other areas. The nesting birds not participating in the harassment can raise their vulnerable chicks safely if the crows are diverted elsewhere. While some birds attack directly, others are serving as decoys.
Conclusion
In summary, small birds most often attack crows to defend their territories, nesting sites, food sources, and to protect themselves from potential predation. Crows are intelligent enough to realize the tiny birds pose them no serious harm. Their response of retreating, fighting back, calling for help, or waiting patiently indicates that crows do not feel seriously threatened by the attacks. While the barrage of dive-bombing birds may seem furious, the skirmishes are mostly bluster and sparring. These inter-species conflicts help maintain natural balances as both crows and small birds seek to establish dominance and protect their young. After a few minutes of skirmishing, the crows inevitably fly off in search of easier meals, much to the relief of the plucky little birds that value their space and safety.