Gulls (family Laridae)
There are 25 species of gull that can be found in California; however, some are more common than others
Ring-billed gull, Larus delawarensis (most common of the four species described in this account. Likely to nest on flat roofs.)
Herring gull, L. Argentatus
Great black-backed gull, L. marinus (Although any of these gulls may eat the eggs and young of other seabirds, including endangered species, the great black-backed is so much larger than the others that it poses more of a threat.)
Laughing gull, L. Atricilla
California gull, Larus californicus
Laughing gull is the smallest, at 16–17″ high. Next is the ring-billed, then the herring, with the great black-backed gull standing 28–31″ tall. The California gull is 20.4-22.8” tall.
Signs of their presence:
The bird itself is the most obvious sign.
Feathers and droppings.
Sounds: Varied, depending on species. May hear the kleew kleew, hiyak, kyow, the ha ha ha of the laughing gull, a plaintive mewing, and a stacatto gah gah alarm call.
Nest: Size is proportional to the size of the bird. They’ll nest in low trees and on flat roofs, especially those covered with gravel or rocks. The nests are often a mere scrape in sand or gravel, but they will add natural materials and bits of trash. Herring gulls make the most elaborate nests of the four, using sticks, other plants, and debris. Ring-billed gulls also use debris, but they favor lighter plant materials, such as dried grasses and weeds.
Opportunist. Gulls eat fish; shellfish; bird eggs and nestlings (they prey mostly on seabirds); insects; worms; grubs; mice; carrion; and garbage. They will steal food out of a person’s hand.
Typical activity patterns:
Social style: Gregarious. Most are colonial nesters.
Daily activity: Diurnal.
Migrates? In the spring, they’ll migrate north as the ice breaks open on lakes and rivers. In late spring, they’ll seek a more secluded area, such as an island, for breeding. In late summer, they’ll gather along the coast and then migrate south with the onset of cold weather. Some gulls remain all year, spending the winter near the open water of oceans or estuaries. Most gulls no longer migrate far, because people provide abundant, year-round food sources.
In California, gulls can be found throughout the state. They are common in areas near lakes, ponds, beaches, and shopping lots.
Lakes, rivers, beaches, estuaries, mudflats, islands, harbors, ponds. Gulls adapt well to rural, suburban, and urban environments and will use agricultural fields, fish hatcheries, airports, landfills, reservoirs, parking lots, flat roofs, parks, malls, and athletic fields. In the winter, gulls seek open water, moving to the ocean, estuaries, and the Great Lakes.
Territory and home range:
Highly territorial on their breeding ground, defending their nest sites, which they’ll likely return to the next year. Prime territories are in the center of the colony.
Pair bonding style: Monogamous. Both parents care for the young.
Breeding dates: April–May.
Egg-laying dates: May–June. Most have one brood/yr.
Clutch size: 3–5 eggs.
Eggs hatch: 21–28 days after they’re laid.
Fledging dates: 4–5 weeks.
Amount of time young remain with parents beyond fledging date: Remain with colony.
Common nuisance situations:
Time of year: Any time of year.
What are they doing?
Steal fish from boats and hatcheries.
They are involved with more aircraft collisions than any other group of birds, because they’re plentiful, widespread, gather in large flocks, and are large birds.
Eat livestock feed and fruits (such as cherries).
Gather in large numbers in parking lots, near restaurants, marinas, food-processing plants, and parks. Their droppings foul objects and buildings. They can be raucous.
If they gather in large numbers, their droppings can contaminate public water supplies.
Mob people, trying to steal food from them.
They may eat the eggs and nestlings of endangered seabirds, such as the piping plover.
They sometimes cause a nuisance when they nest on rooftops.
Disease risks: cryptosporidosis, E. coli bacteria
Legal status in California:
Federally protected migratory birds (under the Migratory Bird Treaty Act).
Federal depredation permits are required to capture, handle, or kill gulls, or disturb their eggs or nests (if there are eggs or young in the nest). Most gull management is handled by USDA-APHIS-Wildlife Services or state agencies, under the direction of the USDA-APHIS-Wildlife Services.
A landowner may chase or disperse gulls at any time without a permit, as long as the gulls are not physically harmed.
For information on specific control techniques contact your local Fish and Wildlife office.
Often, community cooperation is critical for effective solutions to nuisance problems caused by gulls. If you’re confronted with a large colony nesting on a rooftop or at a landfill or airport, work with government wildlife biologists, because they have the option of using additional techniques that require federal permits. In some cases, these techniques are far more effective, or are an important part of the strategy. If this is a new problem, you may be able to deal with it successfully using only the techniques that don’t require permits.
Remove artificial food sources (garbage, livestock feed, fish from hatcheries and boats):
It’s not easy to control their food sources because gulls are highly adaptable, but you don’t have to put out the fine china, either. Focus on the areas that provide their most favored foods and restrict the gulls’ access as much as you can.
If anyone is feeding the gulls, persuade them to stop.
Put signs out in areas where the birds are being fed; telling people to stop feeding them and why they shouldn’t feed them
Clean up any garbage piles. Keep garbage cans and dumpsters closed securely, and the areas around the containers clean.
Gulls also feed at fish docks, sewer outflows, food processing plants, trawlers, and feedlots. Keep those areas clean and try to frighten the birds away.
Use a grid-wire network of highly visible stainless steel wire (28 gauge) or 80-lb. nylon monofilament line to protect large outdoor areas, such as fish hatcheries, garbage dumps, landfills, reservoirs, livestock feedlots, and fields. String the lines parallel to each other, about 15 feet apart and about 8 feet off the ground (a 15×15′ grid also works well). This technique is highly successful with gulls.
Make roosting and loafing sites less appealing:
Turn off fountains to encourage earlier freeze-up of ponds.
Let the grass grow to a height of 8″ or more to discourage gulls from resting in parks, playing fields, airports, and around ponds. This may work for ring-billed and laughing gulls but not herring gulls.
Filling or draining ponds, such as those near malls and office parks, may discourage gulls. With natural wetlands, this would require additional permits.
To keep them off ledges:
fasten wood, stone, sheet metal, styrofoam, or plexiglass “plates” to the ledge at a 45° angle so they can’t comfortably perch there.
Install one of the sharply pointed, steel exclusion devices, such as porcupine wire (prongs point out in many angles), ECOPIC™ (vertical rods), Bird Coil® (a steel coil that looks like a slinky), or nets.
Stretch steel wire (28-gauge) or monofilament line (80-pound) in parallel lines across the area. The lines must be very tight, so fasten the wires to L-brackets with turn buckles to remove slack. Attach the brackets to the wall using cable clamps or aircraft hose clamps, which can handle the high torque load on the wires. (Commercial versions are available, too, and may be easier to use.) Steel wire is more permanent and requires less maintenance than monofilament line.
To keep them off rooftops or away from parking lots and other flat areas: Install a 15×15 ft. grid-wire network (described earlier) or nets.
Frighten them away:
Visual scare devices, such as helikites (a kite with an attached balloon) or a laser (the Avian Dissauder®) may frighten the birds away from the site.
Try noisemakers such as tape-recorded gull distress and alarm calls, shell crackers, and propane cannons. They’re most effective when the birds are airborne.
Hazing, with trained birds of prey (usually falcons) or radio-controlled aircraft that look like falcons may also work. This technique is often used at airports.
NWCOs with a commercial pesticide applicator license:
Nontoxic repellent: Gulls don’t like to land on surfaces that have been treated with sticky polybutene repellents. But polybutenes can affect other species, and they can be messy and hard to remove. For these reasons, consider restricting your use of this tool to indoor applications. And how often do gulls cause problems indoors? You have better options.
Control their reproduction by removing their nests or disturbing their eggs so they don’t hatch:
NWCOs are unlikely to be involved with these efforts, but here’s an overview. Many factors influence the control strategy, including the size of the colony, how long the birds have nested at that site, and whether the goal is to chase them away or to stop them from breeding. Let’s say the wildlife biologists will be removing eggs as part of their gull management. If the gulls have just chosen a new site, the wildlife biologists may remove eggs as soon as they’re laid because the gulls may just fly off and seek a better breeding site. But if it’s a large colony that’s well-established, the gulls will not easily abandon the site. In this case, the biologists may focus on trying to break their breeding cycle, instead. They may wait until the birds have been incubating for a week or two before they remove the eggs, because then the gulls will be less likely to lay more eggs. The biologists may repeat the egg removal after another two weeks.
Egg disturbance techniques (oiling, addling, puncturing, or removing eggs, or substituting dummy eggs) are most effective when the colony is small. With larger populations, some of these techniques, such as addling, puncturing, and substituting dummy eggs, are probably impractical because they’re labor-intensive and time-consuming. Also, you’d need to tamper with nearly every egg to ensure success, and that grows more challenging with larger flocks.
One disadvantage of these techniques is that if they may take several years to work—if they work at all. New birds might join the flock, increasing the numbers you’re trying to reduce. Birds that fail to hatch eggs successfully might move to a new breeding area and cause a nuisance there, so this approach might not be neighborly. Some biologists believe that gulls that have taken to nesting on roof tops will continue to seek roof tops, for example. In such cases, they recommend removing the adult birds.
Of all these egg disturbance techniques, the only ones that are really practical in most situations involving gulls are removing the eggs outright or oiling them. Generally, the colony is just too large for the other techniques.
Oiling eggs: Coating eggs with corn oil prevents gases from passing through the shell so the embryo suffocates. The eggs are either sprayed with oil or dipped into a container of oil, then put back into the nest so the parents will continue incubating them. If the eggs are removed, the gulls usually seek a more secure area in which to lay another clutch. In an established colony, if used by itself, this technique may not eliminate the problem.
Removal of eggs: If it’s at least 1–2 weeks into the incubation, the eggs can probably be removed without prompting the female to renest. She may be less biologically able to lay eggs, but don’t count on it. Return in two weeks to remove any new eggs. Once the gulls are off the nest, try to move them. If there are no chicks, you can harrass them with such techniques as hazing. If there are chicks, you cannot harass them without federal and state permits. Then install a barrier, such as a net, to keep the gulls from landing in the area. If you can’t install an exclusion device you may need to repeatedly remove the eggs, but in time, this treatment may convince the gulls to abandon the site.
Nest removal: If there are no eggs or young in the nest you would not need a federal permit as long as you do not accidentally take birds. The gulls will often attempt to find a more secure nesting area and start again, so expect to repeat this treatment every two weeks. Eventually, this may convince the colony to abandon the site.
It’s unlikely that a NWCO will trap gulls to solve a nuisance problem, because of several practical issues. Permits would be required, from the US Fish and Wildlife Service. You need specialized equipment, and it tends to take a lot of time and effort. Gulls are likely to return to the site, too. The nonlethal methods described in this account are a much more practical approach to dealing with the problem, especially in urban areas.
USDA-APHIS-WS staff may use a highly restricted drug, alpha-chloralose, to capture gulls, or to disperse flocks.
Preferred killing methods:
Requires a federal depredation permit from the U.S. Fish & Wildlife Service
Shooting, using a shotgun or rifle
Acceptable killing methods:
There are toxic pesticides registered for the control of nesting gulls (herring, ring-billed, and great black-backed gulls) in some areas.
Stunning and cervical dislocation
Stunning and decapitation
Control strategies that don’t work particularly well, or aren’t legal in California:
Ultrasonics don’t work. Birds can’t hear them.
Chase the birds away when they land, this may work for the short term, but the birds will just come back when you leave or aren’t there
For information on pesticides follow the link, https://www.cdpr.ca.gov/