Pest birds are wild bird species that cause property damage, health hazards, or significant nuisance when they roost or nest in close proximity to people. The most common pest birds in the United States are pigeons, European starlings, and house sparrows, all three of which are non-native species with no federal protection. Other species like gulls, crows, and Canada geese can also become pests in specific settings, though they carry legal protections that limit how they can be managed.
Which Birds Are Considered Pests
Pigeons (also called rock doves) are the most widespread urban pest bird worldwide. They thrive in cities because buildings mimic the cliff faces they evolved to nest on, and human food waste provides a reliable diet. A single breeding pair can produce up to 12 offspring per year, and flocks grow quickly in areas with consistent food sources like outdoor dining areas, loading docks, and transit stations.
European starlings and house sparrows were both introduced to North America in the 1800s. Starlings travel in enormous flocks that can number in the tens of thousands, overwhelming rooftops, agricultural operations, and airport runways. House sparrows are smaller but aggressive nesters, often displacing native species from birdhouses and building nests in ventilation systems, signage, and warehouse rafters. Because all three of these species are non-native, they are exempt from the Migratory Bird Treaty Act, meaning property owners can remove them and their nests without a federal permit.
Native species like gulls, woodpeckers, and swallows sometimes cause similar problems but fall under different rules. The Migratory Bird Treaty Act protects nearly all bird species naturally occurring in the U.S. under treaties with Canada, Mexico, Japan, and Russia. Under this law, no one may take, possess, or destroy the nests or eggs of a protected species without a valid federal permit. This distinction matters: removing a pigeon nest from your building is legal without paperwork, but disturbing a barn swallow nest during nesting season is a federal violation.
Property Damage From Pest Birds
Bird droppings are the primary source of structural damage. Pigeon and starling feces are highly acidic, and over time they corrode metal, stain stone and concrete, and degrade roofing materials. Accumulated droppings on rooftops can clog drainage systems and add enough weight to stress older structures. On commercial buildings, the cleanup and repair costs can reach thousands of dollars annually.
Nesting materials create their own problems. Birds that build nests inside ventilation ducts, gutters, or rooftop HVAC units can block airflow, create fire hazards, and force expensive equipment repairs. Starlings are particularly notorious for stuffing nests into dryer vents and bathroom exhaust fans in residential homes, sometimes going unnoticed until airflow drops or a burning smell appears.
Health Risks From Droppings and Nests
Dried bird droppings can harbor a fungus called Histoplasma capsulatum, which causes histoplasmosis when its spores become airborne and are inhaled. The fungus thrives in damp soil rich in organic material, and it’s especially common in pigeon coops, old barns, and areas beneath long-term roosts. According to the Mayo Clinic, spores often enter the air during demolition, construction, or cleanup projects that disturb contaminated soil or accumulated droppings. Most healthy people who inhale the spores experience mild flu-like symptoms or none at all, but the infection can become serious in people with weakened immune systems or chronic lung conditions.
Bird droppings also carry bacteria responsible for salmonella infections and can harbor another fungus that causes cryptococcosis, a disease that primarily affects the lungs and central nervous system. These risks are highest in enclosed or semi-enclosed spaces where droppings accumulate undisturbed for long periods, like attics, warehouse lofts, and air handling plenums. If you need to clean up a large accumulation of droppings, wetting the material down first prevents spores from becoming airborne, and wearing a respirator rated for particulate matter is essential.
Bird Mites and Secondary Infestations
One of the most unpleasant surprises from a pest bird problem happens after the birds leave. In the weeks following a nest being abandoned, bird mites that lived on the chicks and adults lose their host and migrate into living spaces looking for a blood meal. They climb walls, cross ceilings, and end up in bedding. The most common species affecting humans is the starling mite, Ornithonyssus bursa.
Bird mite bites cause intense itching, swelling, and raised reddish spots on the skin. They’re often misdiagnosed as bites from other insects or even as a rash, making the source frustrating to identify. The good news is that bird mites cannot complete their life cycle on humans, so infestations are self-limiting once the nest and any remaining nesting material are removed. They are not associated with transmitting any infectious disease. The key to prevention is removing old nests from eaves, vents, and wall cavities before mites have a reason to look elsewhere for food.
Physical Deterrents and Exclusion
Bird spikes are the most commonly installed physical deterrent. They prevent large birds like pigeons, gulls, and crows from landing on ledges, signs, and rooflines. Spikes come in two-foot sections with flexible bases that conform to both flat and curved surfaces. They can be glued with outdoor-rated construction adhesive, screwed into wood (at least one screw every six inches), or zip-tied to pipes and beams. One tube of adhesive typically covers about 25 feet of spike strip. The critical installation detail: leave no more than one inch of open space in front of or behind the spike strip, or birds will simply land in the gap. Spikes work well for pigeons and gulls but are less effective against sparrows, which are small enough to squeeze between the points.
Bird netting is the most reliable exclusion method for completely sealing off an area. It’s used under loading dock canopies, in warehouse bays, around rooftop equipment, and over agricultural crops. Netting comes in different mesh sizes to target different species. A three-quarter-inch mesh excludes sparrows and all larger birds, while two-inch mesh stops pigeons and gulls but lets smaller birds through. Properly installed netting, tensioned and sealed at every edge, is close to 100% effective, but it requires professional installation for large or complex areas and periodic inspection for tears or sagging.
Shock track systems are low-profile electrified strips that deliver a mild electric pulse when a bird lands, similar to an electric fence for livestock. They’re nearly invisible from ground level, making them popular on historic buildings and high-end commercial properties where aesthetics matter. The shock doesn’t harm the bird but trains it to avoid the surface.
Population Control With Contraception
For large, established pigeon flocks, physical deterrents alone often just push the problem to another part of the building or a neighboring property. Flock contraception offers a different approach. A product called OvoControl uses nicarbazin, a compound that reduces egg hatchability, delivered in kibble-sized bait from automated feeders on rooftops. It’s non-toxic and doesn’t harm the adult birds.
In a controlled study conducted in San Diego, a flock of 150 pigeons was treated with OvoControl over 12 months. The treated population declined by 53%, while an untreated control flock nearby remained unchanged. The method works gradually through natural attrition: fewer chicks survive to replace older birds that die. It’s most practical for property managers dealing with large urban flocks where trapping or exclusion isn’t feasible across an entire area. The feeding program needs to run continuously, typically through automated rooftop dispensers on timers, to maintain suppression year over year.
Other Deterrent Methods
Visual and auditory deterrents, like reflective tape, predator decoys, and ultrasonic devices, are widely sold but have limited long-term effectiveness. Birds habituate to static threats quickly. A plastic owl on a rooftop may scatter pigeons for a few days, but within a week or two the flock treats it as furniture. Rotating or moving decoys last somewhat longer, and combining multiple methods delays habituation, but no visual deterrent alone solves a persistent roosting problem.
Habitat modification is often the most overlooked and most effective long-term strategy. Birds stay where food and shelter are available. Securing dumpster lids, eliminating standing water, cleaning food waste from outdoor areas, and sealing entry points to attics and wall cavities removes the resources that attract pest birds in the first place. In agricultural settings, changing crop harvest timing, covering feed storage, and removing spilled grain near barns can dramatically reduce starling and sparrow pressure without any hardware installation.
For protected native species causing problems, like gulls nesting on flat commercial roofs or Canada geese overrunning a park, a federal depredation permit from the U.S. Fish and Wildlife Service is required before any lethal or nest-removal action can be taken. Many states also have their own permitting requirements layered on top of federal rules. Non-lethal harassment of protected species, such as trained dogs chasing geese from a property, is generally allowed but varies by jurisdiction.