VETEBRATE PESTS: Jonathan Livingston Seagull The Pest

Once upon a time, seagulls were only familiar to those who grew up or vacationed near the ocean. But now, not only are seagulls familiar to nearly everyone, including farmers thousands of miles inland who have never been to the coasts, but many people consider these graceful flying birds as mere pests.

GULL FACTS. Gulls belong to the avian family Laridae of which there are 23 North American species. Many common gulls appear similar; they are robust birds with webbed feet and slightly hooked beaks. These birds have long wings that help them achieve graceful, acrobatic and skilled flights. Most gulls nest in colonies on sand- and gravel-covered shorelines and islands. They construct their nests on the ground and usually produce three eggs per clutch. Only one brood is raised per year. Most gulls are fledged by about one month of age, after incubation periods ranging from three to four weeks.

Seagulls feed on a wide variety of natural and people-related foods. On the water, they eat all types of aquatic animals and serve as scavengers of dead fish or fish refuse as produced by boaters or people along the shore. The seagull’s webbed feet enable it to aggressively dive and swim underwater to chase and collect aquatic foods. On land, they are opportunists, similar to the feeding behavior of pigeons and sparrows. Thus, they will take garbage, feed on insects, small vertebrates and even on the eggs and young birds of any nearby nesting seabirds.

Throughout the past decade, gulls have become annoying pests to many in urban and rural areas in the United States. The two most troublesome species are the ring-billed gull (L. delawarensis) and the herring gull (L. argentatus). The populations of these gulls around some cities near water areas are exploding. In Toronto, for example, one gull colony increased from 20 pairs in 1973 to about 80,000 pairs by 1982. And a colony of laughing gulls in the bays outside of New York City increased from 15 pairs in 1979 to 7,600 pairs by 1990.

Obviously, the pest gull species are learning to adapt well to urban environments near shores and water areas. But large flocks of some gull species also have been seen hundreds of miles inland feeding and loafing in all types of farming fields. Because they are opportunists and adapt easily to human environments, gulls provide an excellent model of urban pest.

SIGNIFICANT PESTS. In some areas, gulls are a more significant bird pest than pigeons and sparrows. Gull damage ranges from mere annoyance to serious safety threats. Their droppings can be especially damaging and annoying around plane hangars, parking lots, commercial signs, city statues, boat yards and rooftops. On a more serious level, seagulls are responsible for more aircraft collisions than any other bird species.

Gulls have become important food pests because of the threat of gull fecal contamination of food-serving areas and surfaces. Around many trendy outdoor restaurants and cafes in revitalized urban areas, gulls annoy outdoor diners and defecate on walkways, tables, chairs and rooftops. When the droppings accumulate in stagnating water (or in city water reservoirs), the chances of human disease transmission can increase.

In coastal cities, such as Philadelphia, Boston, New York and others, gulls have become serious pests for various large food-processing and warehousing distribution centers. This is especially true in warehouses and distribution centers located along waterways and bays, where these buildings contain long, flat-roof construction. This is ideal for gull behavior and biology. Of course, such operations also generate a relative large amount of food scraps.

Gulls also have negative ecological impacts because they are predators of several desirable species of seabirds during the breeding season. Because of the increases in gull populations, the detrimental impact on attractive seabird populations may be substantial.

CONTROLLING GULLS. Gull management is highly situational. Specific local conditions must be carefully analyzed before any program is implemented. In the majority of cases involving pest management professionals, gulls are managed via integrated approaches using exclusion and repelling efforts, in addition to essential sanitation programs (where the gulls are drawn to the site because of food) by the client.

Many of the same mechanical repellents/exclusionary devices such as prickly wires and tight wire strands that are used against pigeons and sparrows on buildings can be modified or adapted to be used against nuisance gulls. Some bird repellent manufacturers now offer highly customized wire repellents designed specifically to keep gulls off of the tops of commercial signs, light poles, telephone poles and boat piers.

For example, some wire repellents have thin, stainless steel rods that rotate in the breeze and wave menacingly, interfering with birds as they attempt to land. In other cases, parallel-spaced wires exclude gulls off large flat roofs, garbage dumps and similar situations. But such programs require guidance from professionals experienced in gull exclusion efforts using the wire grid system or by product distributors and manufacturers.

Various chemical repellent gels and pastes also are registered against gulls to prevent them from landing on posts, beams and ledges. These materials are best matched for those situations where quick results are needed, but they may need to be replaced relatively frequently depending on local climatic conditions, temperature and water conditions, etc.

Because installation labor can be the most expensive element associated with bird repelling work, chemical repellents are not cost effective for large jobs or for jobs where the gulls are loafing in hard-to-reach areas. Methyl anthranilate is sometimes applied as a stagnant water treatment and/or fogging agent is sometimes considered for repelling gulls from around buildings and rooftops.

However, efficacy data is lacking about this repellent on gull species under a wide range of conditions. Some preliminary trials have been conducted with the repellent product Flight Control® against gulls, and thus far the results are promising. Check your local product distributor for additional information and use potential.

In cases of new and minor infestations, harassment campaigns using water jets have been tried. Yes, gulls hit with water jets will move. But this approach is not exactly environmentally friendly and may not offer permanent results. The precious time spent conducting such campaigns may be better served installing quality mechanical wire repellents.

OTHER OPTIONS. Management programs that involve killing pest gulls are also available. However, all seagulls are classified as migratory species and are protected by federal laws and/or state laws. Thus, gulls cannot be managed via lethal programs without special permits. In some areas, lethal means are allowed only after it has been demonstrated that all non-lethal approaches have been tried and exhausted. Consequently, most professionals avoid lethal programs and focus on mechanical repellents. Moreover, most professionals do not wish to be vulnerable to the possible clamor that can result if bird protection groups hear of a pest professional killing migratory bird species (even killing non-protected birds such as pigeons can create substantial headaches).

Nevertheless, Avitrol concentrate is federally registered for the control of herring gulls that are feeding, nesting, loafing or roosting near or in the vicinity of sanitary landfills, airports and structures. State and federal permits are required for Avitrol against gulls. Mortality can be controlled by careful use of bait quantities and dilutions. But to achieve the desired frightening effect of Avitrol, some gulls must succumb to the effects of the compound.

The avicide DRC 1339 Gull Toxicant 98% Concentrate is a Restricted Use Pesticide registered for the control of nesting herring gulls, great black-backed gulls and ring-billed gulls. Its use is limited to coastal areas containing high gull populations. The toxicant is mixed with margarine and spread on bread, which is then placed directly on gull nests. This toxicant can only be used by U.S. Department of Agriculture personnel or those persons under their direct supervision. Other specialized gull management programs involve personnel operating under special permits to conduct egg and young removal and egg sterilization programs. Information on these programs is available from the U.S. Department of Agriculture and the Animal and Plant Health Inspection Service (available within each state). USDA is a great source for seagull management updates as well as providing information on obtaining proper permits.

The author is president of RMC Pest Management Consulting and can be reached at 765/939-2829 or via e-mail at rcorrigan@pctonline.com.