Preservation Note 7

Bird Deterrence

Specialties

August-91

Pest Control-10290

Bird Deterrent Systems

A study of bird deterrent systems performed for the General Services
Administration (GSA) by Cooper-Lechy, Architects in 1980 found that
neither audio repulsion (distress calls), \"scare\" systems (plastic
owls, rubber snakes), nor poisoning (\"baiting\") have long term effects
on pigeons and starlings in an urban environment. The study also found
that tactile systems (sticky gel, porcupine wire, electrified shock) are
harmful to masonry as well as ineffective. Numerous other studies
confirm these conclusions.

Recent advances in plastic netting and wire anti-roosting systems offer
a potentially nondestructive solution for eliminating a variety of
nesting and roosting habitats at historic buildings. Anti-roosting wire
systems, also known as \"pin and wire\" and \"trip wire\", consist of a
series of parallel wires of differing height, supported by narrow pins
and held under tension by small springs to prevent pigeons from gaining
a foothold on ledges. Plastic netting, initially developed for
agricultural use, provides a vertical or horizontal barrier to areas
where birds seek shelter and build nests. There are many types of
netting and a variety of attachment methods. Only a few of these are
acceptable for use on historic buildings.

Proposals for installing bird deterrent systems on GSA buildings will be
reviewed on a case by case basis by the Regional Historic Preservation
Officer (RHPO), in consultation with the State Historic Preservation
Officer and Advisory Council on Historic Preservation, as required by
Section 106 of the National Historic Preservation Act.

Guidelines for designing and specifying birdproofing systems follow:

Clean First: Clean oil from surfaces prior to installing bird deterrent
systems. This removes the corrosive droppings from building materials
and permits monitoring the effectiveness of the system. Pigeon droppings
are also a health hazard: specify removal using the attached guideline
specifications distributed by the Regional Entomologist, Dr. Albert
Greene (202) 708-6948.

If possible, coordinate birdproofing with contracts for general exterior
cleaning: install systems immediately after cleaning is completed, or in
sections as cleaning progresses.

Acceptable cleaning materials are water, dilute detergents specifically
formulated for the type of masonry on which they are being used, and
poultices specifically formulated for the masonry on which they are
being used. All cleaning solutions other than water must be reviewed in
writing by the RHPO.

Removing existing systems: Dismantle existing, unapproved deterrent
systems before installing new deterrent systems. Use this rule of thumb
for dismantling electrified shock systems: if bolt supports can by
extracted without damaging masonry, remove bolts and patch holes with
mortar matching stone. Otherwise, snap off exposed portion of bolt by
striking quickly with a mallet, parallel to edge of architectural
element, to avoid breaking stone. Fill void around bolt with sealant.
Consult RHPO concerning removal of porcupine wire adhesive or staining
caused by sticky repellent.

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

New Deterrent Systems

Anti-Roosting Wire: Use .015 inch diameter clear steel or annealed steel
wire. On masonry, support wire with pins driven into mortar joints. On
metal (flashed surfaces), mount pins in clear lexan affixed to metal
surface with clear silicone sealant. Paint pins to match masonry.

Wire spacing and heights are species-specific. The installer must have
an in-depth knowledge of bird behavior and make a site visit to assess
the nature of the building\'s bird problem prior to installation.

Plastic Netting: Use UV resistant, woven, knotted netting only; do not
use molded plastic netting. Specify 1/2 to 3/4 inch knot spacing: larger
spaces allow sparrow entry. Support netting by pins driven into mortar
joints. Tension net with peripheral cabling.

In netting large expanses, use multi-strand polyethylene or
polypropylene netting tensioned by springs or turnbuckles. Turnbuckles,
where they can be installed inconspicuously, are preferred because they
permit adjusting the tension after installation. For small areas, PVC
coated monofilament (single strand) netting is acceptable.

For installations close to grade (i.e. within public view) specify
netting colored to match adjacent masonry (gray, beige, or dark brown).
Well-tensioned black netting is acceptable for upper stories and
shadowed areas above the first floor.

Conceal netting edges by conforming to architectural borders (e.g. along
curve of arch, from stringcourse to stringcourse, between column
capital\'s necking and abacus. Do not create new lines on the facade.
Specify monolithic netting across open expanses to avoid fusible scams.
Seamed netting will be permitted only where seams can be aligned with
linear architectural elements.

Anchors: Supporting anchors must be smaller in diameter than the masonry
joints. Do not penetrate masonry units. Anchors must be removable.
Straight-sided pins and screw eyes are acceptable; piton (expanding)
anchors are not. Prior to installation, paint pins to match masonry.

Sample installation: Required for each type of system, material, and
installation specified. Consult with the RHPO prior to authorizing or
approving contractor\'s samples.

Bidder competency criteria: For netting: \"Submit close-up photographs
descriptions, and references demonstrating four projects successfully
completed within the past five years which are comparable in scale and
complexity to work specified in this contract. Deterrence system and
nature of installation must be comparable to this project\'s
installation. Photographs must be illustrative.

\"For anti-roosting wire: Repeat above, substituting: \"Submit \... two
projects completed within the past five years\".

Guarantee requirement: Minimum five-year guarantee on materials and
effectiveness of installation.

Adverse effects: At location where the system will have an adverse
physical or visual effect on the building, water washing is the only
acceptable solution.

For additional information about bird deterrent systems, call Ms.
Caroline Alderson, Assistant Regional Historic Preservation Officer, at
708-6164.

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

Guide Specifications for Contracted Removal of Bird Excrement on
Building Exteriors

All contractor personnel must wear a National Institute for Occupational
Safety and Health (NIOSH) approve full face respirator with a high
efficiency particulate air (HEPA) filter for screening particles of 0.3
micron size. Dust and particle masks are not appropriate.

Respirators must be used in accordance with OSHA regulation, 29 CFR
1910.134 and GSA policy, PBS P 5900.2C, Chapter 3, section 8. This
includes fit testing of respirators, maintenance, training, and storage
requirements.

All contractor personnel must wear protective coveralls, gloves, boots,
and hats.

Prior to removal, all excrement must be saturated with water under low
pressure to prevent debris form becoming airborne.

Never use metal scrapers or wire brushes on stone, decorative metal, or
other ornamental materials. On historic structures, only nonmetallic
tools (such as plastic spatulas and brushes with natural fiber or nylon
bristles) must be used to remove the excrement.

Removed excrement must be collected in plastic bags, sealed, and
disposed of by the contractor at a sanitary landfill.

All work must be performed from the outside of the building. Building
occupants and the general public must be kept clear of the work site
during all operations. It is the contractor\'s responsibility to provide
all barricades, signage, etc. necessary for public protection.

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

For additional information on bird control, contact Dr. Albert Greene,
NCR Regional Entomologist, (202) 708-6948. For additional information on
bird deterrence and excrement removal on historic buildings, call Ms.
Caroline Alderson, Center for Historic Buildings, Project Manager (202)
501-9156.