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CITY OF

PACIFIC GROVE       

Gull Rooftop Deterrents Design Guidelines

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Why Deter Gulls from Rooftops?

The Western Gull spends most of its winters along the Central California coast. These migratory birds are commonplace along the coast, especially in urbanized locations. The abundance of gulls along coastal towns and cities can be a nuisance to the communities for various reasons. 

Gulls have adapted to foraging for food from dumpsters which are not properly secured, they are bold enough to grab food from people eating outdoors (restaurants, cafés, and beach or park picnics), as well as stealing food from open backpacks and bags when left unattended.

In addition to being a nuisance to the local community and tourists who visit Pacific Grove, gulls leave feces droppings on rooftops and sidewalks. When it rains or when the rooftop or sidewalk surfaces are washed with water, the feces from the rooftops and sidewalks flow with the stormwater runoff. This contaminated runoff leads directly to Monterey Bay adding to the water pollution problem. 

Western Gulls nest and lay eggs from March through May. Nests are made on rooftops, inside eaves, heating, ventilation, and cooling equipment (HVAC equipment), as well as other kinds of vents or ducts, especially in parts of the business district of Pacific Grove. This causes expensive infrastructure repairs and the possible need to replace of such equipment.
 
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Planning Gull Rooftop Deterrent Strategies

Gull rooftop deterrents are methods to deter birds from landing, roosting, and nesting. It is important to use bird control products that do not harm birds, other animals, or people. Western gulls and their eggs are protected under Federal Migratory Bird Treaty Act and the State Fish and Game Code 3503.

Benefits to deterring gulls include:

  • Keeps nesting birds out of expensive rooftop equipment areas and HVAC units
  • Keeps rooftop clean from contaminants entering the storm drain
  • Reduce the need for rooftop cleaning
  • Eliminate smells
  • Decrease bird noise

One effective method of deterring gulls is to remove their ability to land and nest on rooftops. 

For the purposes of this rebate, only deterrent methods listed in this document will be considered for a rebate. Deterrent methods listed decrease perching opportunities on window ledges and roof parapets as well as the landing and takeoff zones of wide open rooftops. There are many kinds of these deterrents and this document attempts to explain a few options available. Research carefully and be aware that gull deterrents:
  • Can be costly depending on the type of gull deterrent chosen.
  • Building owners may need to consult with a wildlife management specialist or deterrent specialist and hire a licensed contractor for installation.
  • Gulls may adjust to the deterrent type which means alternative deterrents may need to be installed.
  • Some deterrents will need to be replaced over time depending on the deterrent. Regular monitoring is suggested.
  • Rooftops are often connected within urban blocks. Consider a gull rooftop deterrent strategy that can be shared by all rooftops in the block. This coordination creates a more effective deterrent and may save overall costs for the product and its installation.
  • Provide the required measures so there will be no damage to the waterproof membrane of the roof where the deterrent will be placed.

Types of Physical Deterrents

Birds quickly adapt to most static bird control devices after exposure to false threats. The gull deterrent devices that are most effective physically block birds. Below is a list of some examples of physical deterrents devices that are applicable for the rebate. Other deterrent systems will not be considered for the rebate.

Steel or Plastic Spike Systems: A row of needles or spikes pointing vertically upwards. The spikes are intended to make it difficult for larger birds to land and perch. This product is generally used on horizontal surfaces such as ledges or window sills, where birds are known to roost or nest.

Advantages: 
  • Easy to install
  • Long life span
  • Environmentally safe
  • Effective against most species of birds
Disadvantages: 
  • Limited to use of ledges
  • Tend to collect debris between the
    spikes (droppings, feathers, nesting material)
  • Cleaning is recommended
  • Ineffective against smaller birds
  • May not affect gull nesting opportunities 

 

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Netting Systems: This system is intended to eliminate the bird control problem by preventing birds from nesting in recessed portions of the building, light wells, or under eaves. The netting protects the buildings. Polyethylene or polypropylene are recommended to make the netting as both materials withstand tension without stretching. Netting to match building colors is available and if hung correctly, can be fairly inconspicuous.

 Advantages: 
  • Suitable for large areas
  • Can last up to 15 years
  • Environmentally safe
  • Effective against most species of birds
Disadvantages:
  • Ineffective if there are gaps or holes in
    the netting.
  • Accurate installation is difficult and can
    be expensive.
  • May obscure some architectural elements
  • Difficult access to roof systems
  • Gulls have been known to perch on
    draped netting 

 

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Anti-Roosting Wire Systems: Consists of a series of parallel wires supported by narrow pins held under tension by small sprints. The spacing of the wires is intended to prevent birds from gaining a strong foot hold on ledges. 

Advantages:
  • Causes minimal damage to building
    as the narrow stainless steel pins
    used for support are small enough to
    be drilled into the mortar joints. If
    and when the pins need to be removed, the holes made can be refilled.
  • Can last up to 10 years
  • Environmentally safe
Disadvantages:
  • Limited to use of ledges
  • Not effective with all species of birds (mostly an anti-pigeon method)
  • May not affect gull nesting opportunities

 

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Installation

Install the gull deterrent device applicable to your rooftop situation. Follow the manufacturer’s recommendations for installation. Building owners may need to consult with a bird deterrent expert and hire a contractor for installation.

Rooftops are often connected within urban blocks. Consider a gull rooftop deterrent strategy that can be shared by all rooftops in the block. This coordination creates a more effective deterrent and may save overall costs for the product and its installation.

Cleaning Rooftops and Sidewalks

Pacific Grove has a stormwater diversion system in place at certain times of year. During the time the diversion system is operable, cleaning/washing of rooftops and sidewalks is permissible. Contact the City of Pacific Grove Planning Division for more information before you clean or wash: 831-648-3190.

If you must wash rooftops or sidewalks when the diversion system is not operating, there are required measures that need to be taken so the wash runoff does not flow into the storm drains. This runoff is considered an illegal discharge which pollutes Monterey Bay. Contact the City of Pacific Grove Planning Division for more information before you clean or wash: 831-648-3190.

 Maintenance

  • Follow recommended maintenance procedures applicable to the deterrent device installed.
  • Wash and Clean surfaces that are contaminated with bird droppings by following Local Municipal Code Requirements and Best Management Practices. Contact the City of Pacific Grove Planning Division for more information, including the best time to clean and wash: 831-648-3190.