Historic Preservation - Technical Procedures

Methods Of Bird Control: Advantages And Disadvantages
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Gra Research - Center For Public Buildings
Bird Control
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Methods Of Bird Control: Advantages And Disadvantages
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This standard identifies different types of bird deterrent systems
available and includes a brief description of how each system is
intended to work by outlining their advantages and limitations.

All of the methods described here have limited effectiveness (see
advantages and limitations below) making the selection of a
suitable bird deterrent system difficult.  Issues of aesthetics and
ethics limit the choices even further.

Important factors to consider when selecting a bird deterrent
system for a particular building include the following:

    -    Bird species (including size, behavior and habits)

    -    Location of building

    -    Climatic conditions

    -    Time of year

    -    Time of day  


Anti-Roosting Wire System, "Pin and Wire" or "Trip Wire":

-    Used primarily for deterring pigeons.  

-    Consists of a series of parallel wires supported by narrow
    pins and held under tension by small springs.  The spacing
    between the wires is intended to prevent pigeons from  gaining
    a strong foothold on ledges.  

-    The wires are sometimes installed at differing heights in
    order to come in contact with the bird's wings, making
    comfortable roosting difficult.

-    Advantages:

    1.   Causes minimal damage to building.  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 with
         mortar, avoiding any further damages to the masonry or
         stone.  In places where this method can not be applied
         directly to the building, Plexiglas may be used to
         provide a means of contact.

    2.   Can last up to 10 years

    3.   Environmentally safe

-    Limitations:

    1.   Limited to use on ledges

    2.   Not effective with all species of birds (mostly an anti-
         pigeon method)

Plastic Netting Systems or "Chicken Wire":

-    An old method developed initially for agricultural use, the
    netting system has been adapted for the protection of

-    This system is intended to eliminate the bird control problem
    by exclusion, preventing birds from nesting in recessed
    portions of the building, in light wells, or under eaves.

-    Two fibers:  Polyethylene or Polypropaline are recommended to
    make the netting.  Unlike other fibers, both of these
    materials withstand tension without stretching.  Both fibers
    can hold up to 30 lbs of tension and should be installed
    holding at least 20 lbs to prevent sags.  Sagging speeds up
    deterioration and makes the system more noticeable.  Netting
    to match building colors is available and, if hung correctly,
    can be fairly inconspicuous.  See 10296-01-R for installation

-    Advantages:

    1.   Suitable for large areas

    2.   Environmentally safe

    3.   Effective against most species of birds

    4.   Can last up to 15 years

-    Limitations:

    1.   Ineffective if there are gaps or holes in the netting.
         Birds can easily fly through them.

    2.   Limited in its protection to certain portions of the

    3.   Accurate installation is very difficult, time consuming
         and expensive

    4.   Obscures some architectural elements

Rows of Metal Spires or "Porcupine Wire":

-    A physical barrier repellent consisting of rows of needles or
    spikes pointing vertically upwards. These spikes are intended
    to make it difficult for larger birds such as pigeons to land.
-    This product is generally used on horizontal surfaces such as
    ledges and window sills, where birds are known to roost or
    nest.  See 10296-02-R for installation guidance.

-    Advantages:

    1.   Easy to install

    2.   Long life-span

    3.   Environmentally safe

-    Limitations:

    1.   Tend to collect debris between the spikes such as bird
         droppings, feathers and nesting material.

    2.   For better effectiveness persistent cleaning is required.

    3.   Ineffective against smaller birds such as starlings whose
         size allows it to use the spaces in between the spikes as
         a nesting site.  


-    Marketed for hearing ranges above 20K Hz; Used to produce high
    frequency sounds as a means of deterring birds from roosting
    or nesting in certain locations (i.e. on buildings).

-    Advantages:  None.

-    Limitations:  Not effective on the hearing range of birds
    (which is roughly the same as humans).

Distress Signal Call Systems:

-    Birds naturally warn other birds of potential danger.  This
    system intends to mimic this idea by producing sounds that
    will signal to surrounding birds the danger of coming near a
    particular building.  

-    Its effectiveness depends upon the type of technology.  Birds
    can differentiate between a real distress call and a tape
    recording of one. One company, however, has been successful
    with a digitized version.  

-    Distress calls are best suited for use against flocking birds
    such as starlings which search for a winter roost.  Once the
    designated spot has been located, the digitized distress calls
    are played repeatedly sometimes as long as two weeks.

-    Advantages:

    1.   Does not obscure the building aesthetics

    2.   Does not impact, alter or damage the building

-    Limitations:

    1.   Noise pollution:  The distress signals are generally very
         loud, thus disturbing the human inhabitants as well.

    2.   There is a possibility of habituation towards the noise.

    3.   The effects are temporary in that birds may return after
         the distress signal is turned off.

Electric Wires:

-    Similar to the electric fences used for livestock.  They
    produce an unpleasant shock when touched or landed upon.

-    Advantages:  None.

-    Limitations:

    1.   Ineffective.  Smaller birds such as Starlings have been
         known to perch on these wires.

    2.   Difficult to maintain

    3.   Difficult to install.  In many cases, installation causes
         more damage to the building because of complicated
         anchoring and connecting devices.

    4.   Even more difficult to remove

    5.   Unsightly

Gel Coating Repellent:

-    Based on gels of polybutylene.  The tactile property is
    intended to irritate the bird's feet.  

-    Advantages:  None.

-    Limitations:

    1.   Tends to absorb airborne pollutants which cause it to
         harden and become ineffective.

    2.   Have a short-term effectiveness, lasting from 18 months
         to 2 years.

    3.   Removal is very difficult and sometimes damaging to

"Scarecrow" Method:  

-    Rubber snakes, glass owls and other commercial devices are
    placed in strategic locations around the building to frighten
    the birds away.

-    Advantages:  This can be a safe and unobtrusive method of bird

-    Limitations:

    1.   This system is generally not effective, because birds are
         able to recognize the artificiality of these devices.

    2.   A reaction to this system is temporary at best, if there
         is even a reaction at all.

    3.   The birds eventually become habituated to these devices
         and may use their artificial adversaries as comfortable

    4.   The effective use of this system requires significant
         human involvement.  These devices must be frequently and
         repeatedly moved from one location to another.

Poisoned Food:

-    There are a variety of chemicals available (listed below).  
    These chemicals are generally discretely sold to specific job
    locations separate from residential areas.

    1.   Avitrol or 4-Aminopyridine:  A bird distress inducing
         chemical.  The affected birds give distress calls that
         scare other birds away.  There is a small percentage of

    2.   Ornitrol:  A steroid based chemosterilant that has been
         effective under trials, but has not performed
         satisfactorily under field conditions.

    3.   Starlicide and Strychnine:  Highly toxic to birds.

    4.   "Toxic Perches":  A solid perch containing a wick soaked
         in liquid toxicant-usually Fenthion.

-    Advantages:  None.

-    Limitations:

    1.   Potentially dangerous to those who handle the chemicals.

    2.   Environmentally dangerous.

Trapping or Shooting:

-    Trapping Advantages:  Though only temporary, this method is a
    humane means of relocating bothersome birds.

-    Trapping Limitations:  Offers only short-term effectiveness
    and requires a substantial amount of human effort.

-    Shooting Advantages:  None.

-    Shooting Limitations:  Inhumane, unethical and dangerous.


-    Homing:  Research has shown that birds use a variety of cues
    to locate their homes.  Such cues range from using smell,
    sound and sight to employing abilities for detecting
    barometric pressure and gravitational forces.

-    Electromagnetics:  Studies have shown that birds are able to
    perceive the earth's magnetic field.  Research indicates that
    birds tend to fly toward the acute angle made between the
    earth's magnetic field and the surface of the earth.  Some
    research has revealed that this phenomenon may be due to a
    tiny magnetic crystal substance lodged between the pigeon's
    skull and brain that allows the bird to detect the magnetic

    How can electromagnetics, then, be used to influence the
    homing patterns of pigeons to guide them away from particular

-    Subsonics (or low frequency sounds):  According to scientists,
    birds can detect low frequency sounds of .06 Hz using their
    inner ear.  To put this in perspective, humans cannot detect
    sounds below 10 Hz.

    Is there a way of transmitting low frequency sounds at high
    intensity as a means of deterring birds from roosting without
    causing destruction to the building or disturbing humans?

                         END OF SECTION
Last Reviewed 2012-02-24