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August 2005
Invaders or Victims?
By Monica Engebretson


Glossy Starling

It seems as if you hear them everywhere you turn: heated debates about immigration and borders, about who ‘belongs’ and who is an unwanted ‘intruder.’ For a nation founded—or ‘invaded’ depending on who is speaking—by immigrants, and claims to still be a land of opportunity and hope for the less fortunate of the world, the U.S. has a profoundly ambivalent, contradictory, and at times, openly hostile view of immigrants.

Ambivalent, contradictory, and hostile are also apt descriptions of our relationship with nonhuman, non-native animals. We can’t seem to decide if they are saviors or scourges. For example, in the late 1800s, the American Acclimation Society set out to deliberately introduce European plants and animals into the U.S.—in part, to make Europeans feel more at home. While the majority of introduced birds perished, the European starling, released in New York’s Central Park in 1890 and again in 1891, quickly became one of the most abundant birds in North America.

Starlings are not the only ‘foreigners’ to establish themselves here. At least 74 free-living exotic parrot species are known to exist in North America. While most escaped or released parrots succumb to the elements, starvation, or predation, certain species in certain climates have shown that they are able to survive in the urban jungles of the U.S.

One of the most abundant free-living parrot species in the U.S. is the monk or quaker parakeet. Thousands of monks were imported into the U.S. from Brazil and Argentina during the 1970s, 80s, and early 90s, and thousands more are produced each year at breeding facilities to satisfy consumer demand for inexpensive small parrots. As a result, large numbers of naturalized monk parakeets now nest in at least 11 states. These flocks are the inevitable result of the exploitation of exotic birds by the pet industry.

Some conservationists worry that non-native birds pose a threat to native bird populations, therefore the ‘intruders’ should be exterminated. Starlings, pigeons, and monk parakeets have been dubbed ‘invasive species’—ones that displace native wildlife and disrupt ecosystems—and have become the target of multiple—and futile—lethal control efforts.

It is important that those who demonize non-native species remember that native bird populations are impacted by a wide variety of factors, most of which arise from human-caused habitat destruction and pollution. Parrots and pigeons tend to inhabit urban areas where many native plants and animals have already been driven out by North America’s most invasive species—Homo sapiens.

Moreover, decades of poisoning efforts have failed to produce lasting reductions in starling, pigeon, and monk parakeet populations.

The Public Health and Safety Smokescreen
Officials who support the killing of non-native birds often use public health risks as a justification for lethal measures. But these supposed risks do not hold up under scrutiny.

For example, in a recent letter to the Animal Protection Institute, the University of Illinois defended its practice of poisoning starlings who congregate around the campus cattle barns. School officials assert that starlings are “known carriers of disease that can be transferred to both humans and domestic animals.” This statement, however, is true of just about any animal, including domestic dogs and cats, and the cattle in the school’s own barn! Even humans are known carriers of serious, infectious diseases.

Further, according to the National Institutes of Health, casual exposure to bird droppings will not place an individual at risk of developing disease. The University has yet to produce evidence that the birds in question pose a significant risk to worker health that either meets or exceeds the risks posed by exposure to the abundant livestock manure in the area, or that the risk posed by the presence of the birds is greater than the risks posed by the spreading of the toxic poisons that would kill the birds.

Histoplasmosis and psittacosis are two diseases that can be contracted from contact with birds or bird droppings, but transmission of disease between humans and free-living birds is extremely rare.

Histoplasmosis is caused by inhalation of spores of the soil-inhabiting fungus (histoplama capsulatum), which grows where bird droppings accumulate. The greatest risk of disease occurs when droppings accumulate for over two years on shaded soil where large numbers of birds (or bats) have established roosts. Fresh bird droppings do not support the fungus.

Psittacosis—an infectious disease with mild, non-specific flu-like symptoms—can infect humans by breathing in the organism when the urine, respiratory secretion, or dried feces of infected birds is aerosolized (i.e., dispersed in the air as very fine droplets or dust particles). Other sources of exposure include mouth-to-beak contact, a bite from an infected bird, and handling the plumage and tissues of infected birds. The Centers for Disease Control (CDC) reports that, “although all birds are susceptible, pet birds (parrots, parakeets, macaws, and cockatiels) and poultry (turkeys and ducks) are most frequently involved in transmission to humans.” The CDC cautions that individuals most at risk from contracting the disease include bird owners, pet shop employees, veterinarians who treat birds, and people who work in poultry processing plants.

It is rare that a genuine public safety threat is at the heart of a conflict between birds and humans. More often, aesthetics or economics are the spurs for lethal control, an approach whose effects are short-lived and wrought with environmental and ethical conflicts.

The Problem with Poison
Lethal control methods are more than just cruel; they are also ineffective in the long-term. For example, poisoning must be repeated year after year to offset the high reproductive rates of animals such as pigeons and starlings.

Two poisons commonly used to kill starlings and pigeons are DRC-1339 (also called starlicide) and Avitrol. DRC-1339 was designed to be a slow-acting poison that causes birds to die slowly and to exhibit behavior associated with excruciating pain. In blackbirds, for example, DRC-1339 takes up to three days following ingestion to cause mortality, by way of irreversible kidney and heart damage.

Avitrol is commonly used in urban settings to control pigeons. Avitrol’s main ingredient, 4-Aminopyridine, is a slow-acting nerve agent. There is no antidote for Avitrol. Birds who ingest even as little as one kernel of Avitrol-poisoned corn exhibit symptoms such as hyperexcitability, salivation, severe tremors, erratic flight, and convulsions. These reactions begin anywhere from 10 to 15 minutes, to four hours after ingestion. Some birds take as long as two days to die. Avitrol persists in the environment and can remain in the soil for up to three years.

In addition to being cruel to their intended targets, such poisons pose risks to other living beings. Children and companion animals may be harmed or killed by coming in contact with poisoned bait or vomit from poisoned pigeons. In 2000, the state of New York banned the use of Avitrol in cities with populations of more than one million due to animal cruelty and public safety concerns.

Non-lethal Control

Fortunately, there are humane non-lethal solutions that can make an area unattractive to birds, thereby reducing bird presence to an acceptable level. Further, many companies, including Nationwide Bird Control ( specialize in humane, non-lethal bird control and provide deterrent products, as well as assistance in administering them.

Examples of effective, long-term and humane solutions to conflicts with birds include:

• Netting to exclude birds from structures.

• Balloons, holographic foil strips, and other visual deterrents that scare unwanted birds away.
• Wood or metal fastened at a 60-degree or greater angle on ledges to prevent pigeons from perching (they prefer a flat surface).

• Bird wires to keep birds from landing on ledges: ranging from single-strand wires placed three to four inches above the ledge of the rail to a more complex wire coil that is wound around a railing or fixed on a ledge.

• Discouraging feeding in public places.

• Commercial fogging agent Rejex-it, which prevents crop depredation from roosting birds. Rejex-it is harmless to people, animals, and the environment, but is distasteful to starlings and other birds, preventing them from roosting where the product has been applied.

In dealing with conflicts involving naturalized, feral or ‘invasive’ animals, it is important to remember that irresponsible human actions are usually the true cause of the problem. We must ensure that our policies toward such animals are not equally irresponsible. Birds, whether native or not, should not pay the price for our mistakes.

Monica Engebretson
is Senior Program Coordinator for the Animal Protection Institute and an exotic bird specialist. For more information contact