Gull Management
Gull Characteristics
Gulls consist of a group 23 species of birds in North America and 44 worldwide. They can generally be identified by their hooked beaks, long tapered wings, robust bodies, and webbed feet. The adults of these species are white with gray and black on wings, back, and head. The different species of this group are further identified by variations in these color patterns. Two of the most common and widespread gull species are the herring gull (Larusargentatus)and ring-billed gull (Larusdelawarensis).
Gull Ecology
Gulls are typically associated with coastal habitats. However, in recent years various gulls species have moved inland and are able to utilize a wide variety habitats and water bodies.
This behavior has allowed the populations of several species, including the herring gull (Larussmithsonianus) and ring-billed gull (Larusdelawarensis) , to increase dramatically. For example, ring-billed gull populations located near the great lakes have increased at a rate of 10% per year since 1930.
Most species of gulls are prey generalists. They are carnivores and will readily feed on live prey such as fish and crustaceans. They will also eat the eggs and chicks of other birds. Gulls will also frequently scavenge carrion and human refuse.
Gulls typically nest in large densely packed colonies. In these locations they commonly nest on the ground or on other flat surfaces. Several species also form their colonies on cliff faces, using the height of this habitat as protection from predators. In the past several decades gulls have begun utilizing rooftops as a nesting habitat. Tar and gravel roofs are particularly attractive due to the nesting substrate that the gravel provides. Elevated rooftops also provide protection from predators in the same way as a cliff band. Nesting adults will actively defend each others nests in a behavior known as mobbing. Adults will attack and harass a perceived predator by diving, defecating, making alarm calls, or even biting/pecking. Nesting seasons vary depending on the geographic locations. However, a clutch of 2-4 eggs is laid in May with chicks hatching approximately one month later. Gull chicks may take up to 2-4 years to reach maturity.
Many North American populations of gulls winter in the southern U.S., Pacific and Atlantic Coasts, and South/Central America. In the summer months they typically migrate to more northern latitudes, the Great Lakes, and Canada.
Gull Conflicts with Humans
High concentrations of gulls have the potential to cause several problems in populated areas. A nesting colony located on a rooftop is a frequent cause of these issues.
Birds nesting in this habitat can cause severe damage to the rooftop reducing its lifespan. They may bring nesting materials onto the roof and deposit feathers which can collect and decompose, damaging roofing material. These materials can also clog roof drains and be drawn into ventilation systems, creating a health risk. Large numbers of birds will also defecate on the rooftop. High concentrations of feces are corrosive and can degrade the roof surface. Over time this will result in structural damage and a roof needing to be repaired or replaced. Adults bringing back food to chicks may also regurgitate on the roof surface creating further damage.
These birds will also defecate on cars, parking lots, walkways, and potentially people entering a building with a nesting colony on the roof. This also creates a health hazard and may prevent the public from using the services provided at a given building.
It is also possible that a gull defending its nesting colony or attempting to feed may attack a person near the colony. This may result in potential liability for the building owner.
A nesting colony of any gull species is also very noisy. If this colony is located in a residential or business area, the noise created by the calls of the birds can greatly disturb people in the area.
All of these impacts can occur at a port or marina.
Gulls may also congregate at city parks with a water source. Feces accumulation at these locations can also result in the closing of swimming areas due to bacteria levels. E. coli, cryptococossis, salmonella, and histoplasmosis have all been found in gull droppings.
Gulls may also feed on agricultural crops such as blueberries. Damage of crops can result in substantial monetary loss. This same depredation can also occur at fish hatcheries. Gulls may also be attracted to cattle feed lots where their droppings may contaminate food sources.
Gull Characteristics
Gulls consist of a group 23 species of birds in North America and 44 worldwide. They can generally be identified by their hooked beaks, long tapered wings, robust bodies, and webbed feet. The adults of these species are white with gray and black on wings, back, and head. The different species of this group are further identified by variations in these color patterns. Two of the most common and widespread gull species are the herring gull (Larusargentatus)and ring-billed gull (Larusdelawarensis).
Gull Ecology
Gulls are typically associated with coastal habitats. However, in recent years various gulls species have moved inland and are able to utilize a wide variety habitats and water bodies.
This behavior has allowed the populations of several species, including the herring gull (Larussmithsonianus) and ring-billed gull (Larusdelawarensis) , to increase dramatically. For example, ring-billed gull populations located near the great lakes have increased at a rate of 10% per year since 1930.
Most species of gulls are prey generalists. They are carnivores and will readily feed on live prey such as fish and crustaceans. They will also eat the eggs and chicks of other birds. Gulls will also frequently scavenge carrion and human refuse.
Gulls typically nest in large densely packed colonies. In these locations they commonly nest on the ground or on other flat surfaces. Several species also form their colonies on cliff faces, using the height of this habitat as protection from predators. In the past several decades gulls have begun utilizing rooftops as a nesting habitat. Tar and gravel roofs are particularly attractive due to the nesting substrate that the gravel provides. Elevated rooftops also provide protection from predators in the same way as a cliff band. Nesting adults will actively defend each others nests in a behavior known as mobbing. Adults will attack and harass a perceived predator by diving, defecating, making alarm calls, or even biting/pecking. Nesting seasons vary depending on the geographic locations. However, a clutch of 2-4 eggs is laid in May with chicks hatching approximately one month later. Gull chicks may take up to 2-4 years to reach maturity.
Many North American populations of gulls winter in the southern U.S., Pacific and Atlantic Coasts, and South/Central America. In the summer months they typically migrate to more northern latitudes, the Great Lakes, and Canada.
Gull Conflicts with Humans
High concentrations of gulls have the potential to cause several problems in populated areas. A nesting colony located on a rooftop is a frequent cause of these issues.
Birds nesting in this habitat can cause severe damage to the rooftop reducing its lifespan. They may bring nesting materials onto the roof and deposit feathers which can collect and decompose, damaging roofing material. These materials can also clog roof drains and be drawn into ventilation systems, creating a health risk. Large numbers of birds will also defecate on the rooftop. High concentrations of feces are corrosive and can degrade the roof surface. Over time this will result in structural damage and a roof needing to be repaired or replaced. Adults bringing back food to chicks may also regurgitate on the roof surface creating further damage.
These birds will also defecate on cars, parking lots, walkways, and potentially people entering a building with a nesting colony on the roof. This also creates a health hazard and may prevent the public from using the services provided at a given building.
It is also possible that a gull defending its nesting colony or attempting to feed may attack a person near the colony. This may result in potential liability for the building owner.
A nesting colony of any gull species is also very noisy. If this colony is located in a residential or business area, the noise created by the calls of the birds can greatly disturb people in the area.
All of these impacts can occur at a port or marina.
Gulls may also congregate at city parks with a water source. Feces accumulation at these locations can also result in the closing of swimming areas due to bacteria levels. E. coli, cryptococossis, salmonella, and histoplasmosis have all been found in gull droppings.
Gulls may also feed on agricultural crops such as blueberries. Damage of crops can result in substantial monetary loss. This same depredation can also occur at fish hatcheries. Gulls may also be attracted to cattle feed lots where their droppings may contaminate food sources.
