Common loons (Gavia immer) are large diving birds found across North America. They are known for their striking black and white plumage and their eerie, haunting calls. Common loons are a symbol of wilderness and solitude, but they are also very territorial birds that are willing to fight fiercely to defend their nesting areas. This leads many lakeside residents and visitors to wonder – are common loons aggressive?
The short answer is yes – common loons can show aggressive behavior, especially during the breeding season when they are defending nesting territories. However, loon aggression usually only manifests as territorial displays and squabbles with other loons. Attacks on humans are extremely rare. With proper precautions, loon aggression is not a major concern for lake residents or recreational users.
In this article, we will take a closer look at common loon aggression – what causes it, what forms it takes, and how to avoid conflicts with territorial loons. We will also examine some of the myths and misconceptions around loons and aggression. Understanding loon behavior and biology allows us to peacefully coexist with these iconic birds that add so much beauty and wonder to freshwater lakes.
What causes loon aggression?
Common loons exhibit territorial aggression because they nest right along the shoreline of lakes. Unlike many other water birds, they do not nest deep in secluded marshes or on islands. This means loons come into regular close contact with humans during the breeding season.
Loons build their nests right at the water’s edge, often within just a few feet of docks, beaches, boats, and swimming areas. A loon pair will aggressively defend an area up to 200 meters around the nest site as their breeding territory. Within this territory, they will attempt to drive off or dominate any other loons that approach. This includes territorial fights with neighboring loon pairs.
Loons are especially sensitive to disturbance while incubating eggs or protecting very young chicks. At these times, they perceive nearly every large animal or human as a potential threat to their nest that must be chased off. Aggression peaks when loons have 1-3 week old chicks riding on their backs, as the parents are extremely protective.
Some other factors that contribute to loon aggression:
– Declining number of lakes – As wetlands are lost, loons nest at higher densities on remaining lakes, increasing territorial clashes.
– Declining number of territorial loons – Younger, nonbreeding loons may be expanding into territories left vacant by declining breeding numbers. Territorial loons will chase these interlopers.
– Food stress – When fish populations decline, loons may become more aggressive while defending dwindling food resources in a territory.
– Human disturbance – Human activities close to nests and increased water traffic can make loons feel threatened and react defensively.
Breeding biology
Understanding loons’ unique breeding behaviors and adaptations also helps explain their territorial defense:
– Loons have a very low reproductive rate – most only raise 1 or 2 chicks per year. This makes them extremely protective of eggs/chicks.
– Loons nest right at water’s edge because they are awkward on land. However, this leaves nests and chicks vulnerable to predators and waves/storms. The parents are on constant guard duty.
– Chicks ride on a parent’s back for warmth and safety for several weeks. Parents become hyper-alert to any animal or human that might approach the vulnerable chick.
Forms of loon aggression
Common loons display a range of territorial behaviors, from subtle warnings to physical confrontations:
Yodeling
The yodeling call, given only by males, serves to advertise that a lake is occupied by loons and to communicate with neighboring loon pairs. More yodeling may indicate higher stress levels and territorial disputes.
Circle swimming
Loons will circle and “patrol” the boundaries of their territory, sometimes confronting intruders. This behavior is common early in the season as pairs establish territories.
Splash diving
A quick, noisy splash dive directed at an intruder functions as an aggressive warning. The loon may be warning away a neighboring loon or a boat that has come too close.
Rushing at the surface
Loons will zoom directly at perceived intruders while “running” across the water. They may make warning calls or change direction at the last moment. This is often directed at other nonbreeding loons entering the territory.
Aerial chases
Loons take flight to chase intruders out of the territory. Aerial pursuits and dogfights between two loons are impressive to watch.
Fighting on the water
Physical confrontations on the water involve bill jousting, rearing up, splashing, and underwater grappling between two loons. Actual physical injury is rare.
How loons attack
When loons do direct aggressive behavior at people, they have a repertoire of intimidation tactics:
– Bill jabbing or nibbling – Loons will jab or gently bite at hands, arms, or equipment in boats. This seems to be “testing” for a response rather than intending harm. Their small, rear-facing bills are not capable of seriously injuring a human.
– Wing flapping – Flapping wings while rushing at people functions as an aggressive display, but poses little real danger.
– Rearing up in the water – Loons can appear larger and more imposing when they pull themselves vertically out of the water and flap their wings near intruders.
– Splashing water – Splashing water with feet and bill makes loons seem larger and creates a dramatic display.
– Underwater attacks – There are a few reports of loons making underwater grabs at swimmers’ feet. No serious injuries have been documented.
Do loons ever attack humans on land?
It is extremely unlikely for a loon on land to attack or intentionally harm a human. Loons are awkward and vulnerable on land, and cannot walk or take off without room for a running start across open water. However, there are anecdotal reports of nesting loons pecking at people who get too close to the nest or chicks.
Avoiding conflicts with loons
While loon aggression is mostly bluster and territorial display, it is easy for humans to avoid antagonizing loons during the nesting season:
– Observe loons only from a distance – 100 meters is ideal. Avoid approaching nests or chicks at any time.
– Prevent pets from chasing or harassing loons. Dogs sometimes try to chase loons out of overenthusiasm. Keep dogs leashed and controlled.
– Give loons a wide berth when boating – stay 30-60 meters away from any loon on open water. Avoid motoring directly at loons.
– Avoid areas marked with loon nesting signs. Steer clear of shallow bays and marshy inlets where nests are likely.
– If loons approach or dive bomb your boat, slowly move away from the area. They are warning you away from the nest location.
– Don’t swim or wade near loon nests or chicks. Be cautious when entering the water in areas with territorial loons.
– Only observe loons from designated viewing platforms or photography blinds at lakes where these are provided.
– Follow fishing regulations and avoid excessive wake from water sports that could swamp nests.
Debunking myths about aggressive loons
Though loon territorial behavior can seem dramatic to us, some popular assumptions about aggressive loons are false:
Myth: Loons attack swimmers
Reality: There are no documented cases of loons drowning or seriously injuring swimmers. Minor nibbling or underwater brushes are the most that have been reported.
Myth: Loons are dangerous to pets or children
Reality: Healthy loons pose little threat to pets or children. There are no verified reports of loons seriously injuring either. Supervise children and pets around water regardless.
Myth: Aggressive display means the loon will attack
Reality: Most loon bluster is just a display. Loons want to avoid injury, so they warn intruders away with splashing and rushing rather than physical contact. Slowly moving away defuses the situation.
Myth: Loons can capsize small boats
Reality: Loons weigh 10-12 pounds and do not have the size, strength or intention to overturn watercraft. Their territorial displays are meant to discourage pursuit or collision by boats.
Myth: Loons are getting more aggressive over time
Reality: Loon populations in most regions are declining, so reports of loon incidents are down. Nesting densities remain similar to historical levels. There is no evidence that behavior is changing.
Understanding loon territorial behavior
To understand common loon aggression, it helps to look at it from the bird’s point of view:
– Each nesting pair relies on a lake’s fish for themselves and their chicks. They don’t want competitors taking this vital resource.
– Loons invest time building their nests in preferred shoreline locations. They strongly defend these sites.
– Their chicks are extremely vulnerable to predators and weather. Vigilant parents must protect them.
– Humans in boats or swimming seem like large, potential threats to the loon family. Their aggression is motivated by fear.
– Much loon bluster is simply territorial signaling directed at other loons, not humans. We often mistake their normal behavior for aggression.
Benefits of territorial behavior
Territoriality allows loons to:
– Carve out areas of sufficient size with enough fish to raise their chicks
– Choose shoreline areas with the best nest locations and escape routes
– Keep other loons from competing for resources or harming their chicks
So while loon aggression can seem disruptive or needlessly confrontational to us, it is key to their survival and reproduction. This nest defense strategy has served loons well over millennia. Appreciating why loons are territorial allows us to peacefully coexist and admire their dedication to their young.
Conclusion
Common loons certainly have a reputation for being territorial and aggressive during breeding season. However, their behavior is simply exaggerated versions of normal nest defense seen in many birds. Loon aggression mainly manifests as blustery displays rather than physical attacks.
With proper precautions like maintaining distance from nest sites and not swimming near territorial loons, humans can easily avoid antagonizing them. While their haunting calls and striking plumage are icons of northern lakes, loons pose little real threat to people. Understanding the biology behind their dramatic territorial behaviors allows us to marvel at the common loon while giving these remarkable birds the space they need to thrive.
| Form of Aggression | Purpose |
| Yodeling call | Signals territory occupation and communicates with other loons |
| Circle swimming/patrolling | Defends territory boundaries |
| Splash diving | Warns intruders away |
| Rushing at surface | Chases intruders, defends territory |
| Aerial chasing | Chases intruders from territory airspace |
| Fighting on water | Establishes dominance and defends territory |
