Barn swallows (Hirundo rustica) are small songbirds found throughout most of the world. They are known for their distinctive forked tails and their habit of nesting inside barns and other structures. Barn swallows are not typically aggressive towards humans, but they will defend their nests if they feel threatened. Here is a quick overview of barn swallow behavior and whether they will attack people:
Quick Answer
Barn swallows are not generally aggressive birds, but they may swoop at or dive-bomb humans who get too close to their nests during breeding season. Their primary goal is to scare away perceived threats. Actual physical contact is rare and unlikely to cause injury. There are a few steps people can take to avoid provoking an attack from nesting barn swallows:
- Avoid areas near barn swallow nests especially during breeding season (usually spring through summer)
- Prevent access to potential nesting sites before breeding season
- Remain calm and avoid excessive motion if a barn swallow dives nearby
- Wear a hat or helmet for extra protection if entering an area with nesting swallows
With proper precautions, the risk of being attacked by a barn swallow is very low. They are not typically aggressive birds and will only harass humans who get too close to their nests while breeding.
Barn Swallow Behavior
Barn swallows are very social birds that live in large colonies consisting of pairs and family groups. They are known for their intricate mud nests, which they attach to vertical surfaces on man-made structures such as barns, sheds, bridges, and homes. Barn swallows mate for life and typically raise two broods per breeding season. The female builds the nest and cares for the eggs and chicks, while the male helps gather mud and defends the nest from threats.
Barn swallows migrate long distances and occupy nesting sites for only a portion of the year. They winter in Central and South America and return to northern regions like North America to breed during the spring and summer. Their breeding habitat coincides with the locations of farms, stables, and other rural buildings that provide sheltered nesting sites as well as open fields and water bodies where they forage for flying insects to eat.
Territorial and Defensive of Nest Sites
Male barn swallows are highly territorial and defensive of their nest sites, especially when females are laying eggs and incubating. They will chase away other barn swallows or competing species that get too close. However, barn swallows pose little real threat to adult humans or larger animals.
Barn swallow attacks are mostly limited to dive-bombing intruders and making close swooping passes overhead. Rarely, they may peck or claw at someone’s head with their feet. Their goal is to startle potential predators into leaving, not cause bodily harm. Any physical contact is usually harmless and does not break the skin.
Increased Aggression in Breeding Season
The risk of being dive-bombed increases during breeding season when barn swallows are most sensitive to disturbance near their nests. Both male and female barn swallows may harass intruders, although male birds tend to be more aggressive. The highest risk periods are when the female is building the nest, incubating eggs, and when there are recently hatched chicks in the nest.
Barn swallows may perceive humans who linger or move close to the nest as a threat to their eggs or chicks. The parents feel an innate urge to protect their offspring and will try to drive the intruder away by flying very close while vocalizing loudly. However, once the chicks leave the nest, the parents tend to become less territorial.
Precautions to Avoid Barn Swallow Attacks
Here are some tips for avoiding unwanted aggression from nesting barn swallows:
Keep Your Distance
Give all active barn swallow nests a wide berth during breeding months. Pay attention to the birds’ behavior as you approach, as they will signal distress and agitation through loud calls when you encroach on their territory. Back away if adult swallows leave the nest and start to dive in your direction.
Cover Your Head
If you must pass close to an active nest, protect your head and neck just in case. Wear a hat, helmet, or hold an umbrella overhead. Keep children supervised in areas where swooping is likely.
Avoid Sudden Movements
If you are dive-bombed, remain calm. Swatting at an attacking swallow will only provoke it further. Move smoothly and deliberately out of the area, or stand still with your arms down until the swallow loses interest.
Prevent Nest Building
To prevent attacks altogether, block barn swallows from building mud nests in undesirable areas before breeding season starts. Close openings in sheds and porches, install barriers like wire mesh or plastic sheeting, or remove existing nests after winter if they are considered a nuisance.
Be aware that barn swallows are protected under the Migratory Bird Treaty Act. Non-lethal exclusion prior to nesting is legal, but destroying or disturbing active nests is prohibited without a permit.
When Do Barn Swallows Attack?
Barn swallow attacks occur most frequently under these circumstances:
- During the nest building and egg incubation period (usually late April through mid June)
- When walking, standing, or sitting very close to the nest (within 5-10 feet)
- Approaching fledglings who have left the nest but cannot fly well yet (late June through July)
- Entering areas where large barn swallow colonies nest together
- Disrupting swallow nests by knocking them down or touching eggs or hatchlings
Swallows may become agitated when humans block their flight paths or linger too long near the nest. Attacks are their way of communicating “back off and give me space!” Once nestlings can fly and no longer need constant protection, the parents usually become less territorial.
Are Barn Swallow Attacks Dangerous?
Barn swallow attacks pose little real physical danger to people. Here are some facts about the risks:
- The birds are small (5-7 inches long) with very lightweight, fragile bones. Direct hits cause bruises or scratches at worst.
- Swallows avoid striking at eyes or other vulnerable areas. They aim for the top or back of the head.
- Injuries requiring medical care essentially never occur. There are no verified reports of hospitalizations.
- A hat or helmet provides ample protection if worn when passing by nest sites.
- Children and the elderly may be at slightly greater risk of falling if startled by a dive-bombing swallow.
While annoying, barn swallow attacks do not pose a true hazard or lead to serious injuries. The birds are just trying to protect their nests using bluffing tactics. Proper precautions like avoiding nests or wearing a hat easily prevent any harm.
Do Male or Female Barn Swallows Attack More?
Male barn swallows tend to be more aggressive in defending the nest site, though females may also dive at intruders. Here’s a breakdown of each sex’s behavior:
Male Barn Swallows
- More territorial due to hormonal changes during breeding season
- Patrol a larger area around the nest and chase away other birds
- Primarily responsible for defending the nest from mammalian and human threats
- Make more frequent close swooping passes at intruders
- Give alarm calls signaling pair to begin group dive-bombing
Female Barn Swallows
- Also defend the nest but usually less aggressively than males
- Stay closer to the nest to incubate eggs and brood hatchlings
- Join in mobbing predators if threat is very near to nest
- May attack if suddenly blocked from returning to eggs/hatchlings
- Stop attacking once nestlings can self-regulate temperature and males take over feeding
In summary, male barn swallows tend to be more intensely protective and account for most instances of dive-bombing. However, female swallows may also attack in certain circumstances, especially early in breeding season when incubating eggs.
How Close Do You Need to Be to Get Attacked?
Barn swallow attacks typically happen when an intruder approaches to within 5-10 feet of the nest. However, the birds may begin acting agitated or giving alarm calls at greater distances. Factors that influence how close you need to get before an attack include:
- Stage of breeding season – swallows are more defensive while incubating eggs or brooding
- Location of nest – more concealed sites provoke attack at shorter distances
- Amount of cover – less vegetation makes swallows guard from farther away
- Abundance of predators – areas with more threats elicit attacks sooner
- Visibility – swallows can detect approaching threats sooner in open areas
- Experience with humans – less exposure makes swallows more wary
A good rule of thumb is to avoid approaching within 10-12 feet of any active barn swallow nest. Pay attention to warning calls and back off if swallows start making distressed vocalizations or leave the nest to dive in your direction. Every situation is different, so look for signs of agitation and give the birds adequate space.
Will Killing Barn Swallows Reduce Attacks?
Killing barn swallows is illegal under the Migratory Bird Treaty Act and will likely increase aggressive behavior, not solve it. Here’s why lethal control is ineffective:
- Removing adult swallows may leave behind vulnerable chicks to die
- Surviving mates often recouple and renest the same season
- New barn swallow pairs will quickly occupy habitat vacated by killed birds
- Destroying nests with eggs or hatchlings is also illegal without a permit
- Lethal control must be continual to have any lasting impact on populations
- Killing nesting swallows causes trauma and stress to remaining birds
A better long-term solution is to exclude barn swallows humanely by sealing potential nesting spots before breeding season or installing non-harmful deterrents like netting or wire mesh. This avoids liability while still preventing unwanted nests. Population reduction should be left to permitted wildlife professionals.
What to Do if Attacked by Barn Swallows
Here are some recommendations if you are harassed or dive-bombed by barn swallows:
- Remain calm – do not panic or flail your arms, as this may provoke further attacks
- Cover your head with a hat, helmet, or backpack for protection
- Keep moving steadily away from the nest until you are no longer deemed a threat
- Avoid the area near swallow nests during breeding season if possible
- Report persistent or aggressive swallows to local wildlife authorities
- Seek medical care if you sustain an eye injury or suffer trauma from falling
In most cases, barn swallow attacks are merely inconvenient and resolve once you move away from the nest site. But it is smart to tell wildlife officials about any exceptionally aggressive birds to head off any potential future incidents.
Can I Destroy Barn Swallow Nests to Stop Attacks?
It is illegal under the Migratory Bird Treaty Act to disturb or destroy active barn swallow nests without a permit from the U.S. Fish and Wildlife Service. Empty nests may be removed after breeding season ends (typically around September). Here are some key considerations:
- Do not remove nests with eggs – this can lead to fines up to $15,000 and prison time
- Avoid displacing nests with hatchlings who cannot yet fly and fend for themselves
- Work with wildlife officials to use non-lethal exclusion methods before nesting begins
- Wait until fall and winter when nests are vacant before removing them
- Deterrents like plastic spikes or netting can prevent rebuilding in problem areas
Prevention is best by sealing off prospective nesting spots early in the year before breeding activity takes place. This avoids negative impacts to swallows while still stopping nests in troublesome locations around homes or buildings.
Conclusion
While barn swallows can certainly be annoying and bothersome when they attack humans who stray too close to their nests, the danger they pose is minimal. These small birds are just following their instincts to protect vulnerable eggs and chicks, not acting out of true aggression. A few sensible precautions like covering your head, avoiding nests, and not provoking the birds are usually enough to prevent any harmful outcomes from dive-bombing or swooping barn swallows. Lethal control is not an ethical or effective approach. As with other wildlife conflicts, empathy, prevention, and non-lethal methods work best for coexisting with nesting barn swallows.
