Small species, including ring-billed, laughing, and Franklin's gulls, may also feed in the air on flying insects. Damage Increasing gull populations in North America during the past century have led to a variety of problems for different segments of society. Gulls cause damage to agricultural crops and threaten human safety at and near airports. They are involved in more collisions with aircraft than any other bird group because they are numerous and widely distributed. The presence of gull roosts near reservoirs increases their potential for transmitting diseases to human populations.
Gulls are predators of several seabirds during the breeding season.
Expanding and colonizing gull populations may have detrimental affects on the breeding performance of these other, often preferred, species. Cultural Methods of Control Habitat modification to discourage gull use of areas includes reducing or eliminating food, nesting and resting sites, and water. Reducing food availability is not easy, because of gulls' adaptability in using a wide variety of foods. Human food wastes, fruit and vegetable crops, insects, earth-worms, and other invertebrates and vertebrates are all potential foods that may require careful control to reduce their availability. Municipalities may find it useful to modify or eliminate artificial feeding sites that gulls have habituated to in recent years, such as garbage dumps and landfills, fish docks, trawlers, food processing plants, sewer outfalls, and livestock feedlots.