Black-backed gulls are large, aggressive gulls that can be found across much of the Northern Hemisphere. They are opportunistic feeders and scavengers that will readily take food from humans, which can lead to conflict. Understanding their behavior and learning ways to discourage them can help reduce problems.
What species are considered black-backed gulls?
There are two species of black-backed gull:
- Lesser black-backed gull (Larus fuscus)
- Great black-backed gull (Larus marinus)
The lesser black-backed gull is smaller with a wingspan of around 120 cm. The great black-backed gull is very large for a gull, with a wingspan up to 175 cm. Both species are slate gray on the upperparts and wings, with black feathers on the back and wings. The amount of black can be variable within each species. The underparts and head are white in adults. Immature birds are mottled brown and take several years to reach adult plumage.
Where are black-backed gulls found?
The breeding range of black-backed gulls includes:
- Northern Europe
- Iceland
- Northern Asia
- Alaska
- Northeastern Canada
- Greenland
They nest on coastal cliffs, islands, and sometimes on rooftops. Outside of the breeding season, they are widespread across more southerly coasts and inland areas.
Range of the lesser black-backed gull
The lesser black-backed gull breeds across northern and western Europe. There are also isolated breeding colonies in central Europe and southern Scandinavia. It winters across western Europe, the Mediterranean, and northwestern Africa.
Range of the great black-backed gull
The great black-backed gull nests in Iceland, Scandinavia, northern Russia, and northern coastal North America. It winters further south along the coasts of Europe and North America.
What do black-backed gulls eat?
Black-backed gulls are omnivorous and opportunistic. Their diet includes:
- Fish
- Carrion (dead animals)
- Rodents and small mammals
- Bird eggs and chicks
- Insects
- Earthworms
- Human food waste
They will scavenge any readily available food source, including garbage. They also prey on eggs and chicks of other bird species. When living near humans, they learn to associate people with easy food sources.
Why are black-backed gulls considered aggressive?
Black-backed gulls exhibit aggressive behavior both in defending nest sites and when seeking food. Reasons they are considered particularly aggressive include:
- They will readily swoop in to steal food, even from people.
- Large size makes them more intimidating.
- May act territorial and attack humans that get too close to a nest.
- Form large, noisy flocks when food sources are available.
- Bold behavior from learning to associate humans with food.
The great black-backed gull is generally considered the more aggressive species compared to the lesser black-backed gull due to its larger size and power. However, bold behavior varies greatly among individual gulls.
Defense of nest sites
During breeding season, black-backed gulls become highly defensive of their nesting territory. They will vigorously attack perceived threats, including humans, that approach too closely. Swooping in from above while vocalizing loudly is meant to startle and intimidate intruders away.
Scavenging food
Flocks of black-backed gulls will readily swarm areas with abundant food, such as picnic areas and garbage dumps. Their loud calls and swooping in to steal food can be aggressive to humans. Some gulls become skilled at snatching food from people’s hands. They learn to associate humans with easy meal opportunities.
Are black-backed gulls dangerous to humans?
Black-backed gull attacks are relatively rare and not usually dangerous. However, their aggressive behavior can pose some risks including:
- Sharp beak can inflict minor cuts or wounds.
- Being struck by wings can potentially cause injury.
- May cause fall injuries if swooping in startles someone.
- Risk of food theft and ruined picnics or outdoor events.
There are a few reported cases of the very large great black-backed gull killing smaller animals. However, serious injuries or fatalities involving humans are extremely unlikely.
Reported injuries from gull attacks
Most injuries from being struck or pecked by a territorial black-backed gull are minor, such as:
- Small lacerations
- Bruising
- Abrasions
Rare cases of more significant injuries include:
- Eye injuries from sharp beak
- Concussions
- Broken bones from falls
However, the vast majority of gull attacks do not result in any substantial physical harm to people.
When are black-backed gulls most aggressive?
Black-backed gulls exhibit more aggressive behavior at certain times of year. Periods when they are more likely to attack or steal food include:
- Breeding season – Late spring through early summer during nesting and chick-rearing.
- Migration – Can be more defensive of food sources during migration seasons.
- Winter – Form large foraging flocks at food sources.
- Year-round at favored feeding sites – Locations like garbage dumps and docks with regular food access.
Aggression is often heighted when the gulls are feeding chicks. Males tend to be more aggressive in defending the nest site, while females are aggressive when foraging for food for their young.
Black-backed gull aggressiveness by month
Month | Aggressiveness Level |
---|---|
January | Moderate |
February | Moderate |
March | Increasing |
April | High |
May | Very High |
June | High |
July | Moderate |
August | Low |
September | Low |
October | Moderate |
November | Moderate |
December | Moderate |
Aggression peaks in late spring through early summer during breeding. It remains relatively high through June then declines. It begins rising again in late fall and winter as large flocks congregate at food sources.
Where are black-backed gulls most aggressive?
Black-backed gulls tend to show more aggressive behavior in these situations:
- On or near their nesting sites
- At sites with abundant food sources – dumps, fish processing plants, etc.
- Crowded areas like parks and beaches where food is often available
- When humans are eating outside or carrying food
They are most defensive and likely to attack on their breeding territories. Anywhere these gulls have learned to rely on human food sources or garbage you may experience more aggression problems.
Nesting territory aggression
During breeding season, approaching too closely to a black-backed gull nest will likely provoke an attack. Nests are often situated on small islands, coastal cliffs, or isolated rooftops. Stay well away from any observed nests.
Feeding aggression
Favored feeding sites, even well away from any nests, tend to attract large, noisy flocks. The gulls swarm any new food sources. They may dive in to steal food or extra aggressively defend any food they capture.
How can human behavior influence gull aggression?
Certain human actions can elicit aggressive gull behavior. Common triggers include:
- Getting too close to a nest
- Attempting to disturb or destroy eggs or chicks
- Providing access to food waste – intentional or unintentional
- Throwing food in the air
- Waving or swinging food items
- Trying to hit or swat at gulls
Well-meaning actions like feeding gulls teaches them to associate humans with easy food. It encourages aggressive food-begging behavior. The safest approach around gulls is to avoid interaction.
Nesting territory triggers
Approaching too closely to a nest signals a threat to gull parents. The territory they defend can extend 50 feet or more from the nest. Give nests a very wide berth to avoid unwanted attacks.
Scavenging triggers
Where gulls congregate to feed, even well away from nests, aggression is likely if they associate humans with food provisioning. Avoiding littering, securing trash cans, and not feeding gulls helps prevent escalated begging and food theft behavior.
How can human conflicts with black-backed gulls be reduced?
There are number of measures that can be taken to discourage negative gull behavior and reduce human conflicts:
- Avoid nesting areas during breeding season
- Secure food waste and trash
- Use enclosed trash bins
- Don’t feed gulls
- Cover food at outdoor eating areas
- Use deterrents like wire overhead grid systems or spikes on ledges
- Population control via egg removal or sterilization
Prevention is the best strategy. Eliminating food access and excluding gulls from problem nesting areas diminishes incentive for aggressive behavior. Ongoing population control may also be warranted in some cases.
Discouraging nesting
Removing nests and eggs from problematic nest sites discourages reuse. Other nest exclusion options include wire grids, slope adjustment, or gravel. Regular maintenance is required.
Removing food incentives
Securing garbage and eliminating hand feeding are two of the most important ways to discourage gull congregations. Once they associate an area with easy feeding, their numbers and aggression quickly escalate.
How do wildlife officials manage problematic black-backed gulls?
In areas with serious gull conflicts, wildlife officials may undertake focused population control strategies. Methods may include:
- Egg removal or sterilization
- Toxic bait (where permitted)
- Trapping and euthanasia
- Culling adults
Lethal control is often a last resort employed only where aggressive gulls present serious danger or cannot be managed through exclusion and behavior modification. Even where culling is used, some level of population remains to avoid opening an ecological niche.
Egg control for population reduction
By preventing eggs from hatching, officials can reduce local gull population growth. Egg removal must be ongoing to offset high reproduction rates. Egg oiling or puncturing are alternate methods but less effective than egg removal.
Control Method | Effectiveness |
---|---|
Egg removal | Very effective |
Egg oiling | Moderately effective |
Egg puncturing | Minimally effective |
Just a few overlooked eggs can still allow a breeding pair to fledge chicks, reducing efficacy of control efforts. So full removal gives the best results.
Culling for immediate reduction
Culling adults and fledged juveniles provides immediate reduction in problem bird numbers. Shooting, trapping, or toxic bait may be deployed where this level of lethal control is deemed necessary. Ongoing removal is still needed to manage populations.
Conclusion
Black-backed gulls exhibit aggressive behavior, especially in defending nests and food sources. Their loud, swooping attacks can threaten human safety and ruin outdoor recreation activities. While injuries are usually minor, they will energetically fend off any perceived threats.
Preventing access to food waste and nest sites is key to modifying behavior. Officials may also undertake egg control or culling where conflicts are severe. While their aggressive nature can be a nuisance, black-backed gulls are still important coastal and inland scavengers.