Franklin's gulls are relatively small gulls that measure 32 to 36 cm in length, feature a 85 to 95 cm wingspan, and weigh 221 to 335 g. Franklin's gulls are the only species of gull that goes through two complete molts in both spring and fall. In breeding plumage, Franklin's gulls feature an entirely black head and each eye is surrounded by a broad, white ring. It's small bill turns bright red with a thin black ring around the tip. The neck, breast, tail and undersides are unmarked white, but the belly may be tinged with pink. Legs and feet are very dark red in color. The back and most of the wings are dark-gray, with a white band along the bottom edge of the wing. Wingtips have three stripes: a band of white, a band of black, and white again on the very tips. The pattern on the wingtips helps to distinguish this species from similar laughing gulls (Larus atricilla) which feature more black on the wings and do not have that distinctive three-band pattern on the wingtips.
In non-breeding plumage, the all-black head reduces to a patchy black to gray hood that covers the top of the head and neck. The forehead and throat become white. The legs and feet turn nearly black as does the bill, which retains a reddish tip.
Juvenile and one-year-old adults feature duller, gray to brown plumage. These young gulls more closely resemble the non-breeding adult plumage as they display a grayish-black hood, and a blackish bill and legs. The neck and back have a brownish tinge and the white tail features a black band along the edge.
Like many hatchling gulls, Franklin's gull chicks are downy and overall speckled with shades of brown and tan to help them blend in to the grass and sticks around them.
Male and female Franklin's gulls are identical in plumage, but males tend to be slightly larger in bill and body size. ("National Geographic Complete Birds of North America", 2006; Burger and Gochfeld, 2009; ; "Franklin's gull Larus pipixcan", 2000)
Franklin's gulls are migratory birds that travel seasonally between North and South America. In late winter or early spring, Franklin's gulls migrate to central Canada and the northern United States to breed. Throughout spring and summer this species can be seen in central Saskatchewan, eastern Alberta, southwestern Manitoba, central Oregon, northwestern Utah and Wyoming, southern Idaho, northwestern Iowa, North and South Dakota, and Minnesota. In late summer and fall these birds migrate south to spend the winter in South America. Franklin's gulls spend the months of December to March along the Pacific coast of South America from Peru to Chile. (Burger and Gochfeld, 2009)
Throughout their range, Franklin's gulls may be found in aquatic habitats including coastlines and inland bodies of freshwater. Franklin's gulls nest alongside inland freshwater lakes or marshes, in the area between open water and dense vegetation. This species uses aquatic, floating nests which are constructed in cattails, on muskrat homes, or on floating vegetation. During migration, these gulls stop to take a break on inland lakes, estuaries, bays, pastures, flooded fields, mudflats, lagoons, river mouths, and harbors. While wintering in South America, Franklin's gulls may be found on ocean beaches, bays or estuaries. (Burger and Gochfeld, 2009)
Franklin's gulls are monogamous birds, meaning that one male and one female form a pair to breed and raise young. These gulls perform many courtship displays to attract mates. After males establish territories, they give calls and toss their heads to attract females that are flying by. If a female responds to a male's display she will stop flying and land in nearby vegetation. Once the female has landed the male turns his back to her so she is unable to see his black head. The feathers on his head stand straight up. The female then turns her back to the male, and they continue alternating looking and turning their backs. During this ritual, either may take a break to peck at vegetation, preen, or drink and then return to courtship. The female may also beg to initiate courtship, and these begging behaviors include walking in front of the male over the nesting platform, head tossing and standing in a hunched position, or pecking at the male’s chin or bill. The male will ultimately regurgitate food, which the female will eat. (Burger and Gochfeld, 2009)
Franklin's gulls are migratory birds that travel hundreds of miles north to breed each spring and summer. In Minnesota and North and South Dakota, Franklin's gulls arrive at the breeding grounds during April and courtship begins several days later. Nest construction occurs before, during, or after pair formation and both males and females may participate. Nests are mounds of floating vegetation that gradually sink during the nesting period. Males, females, and even older chicks will help to add vegetation to keep the nest above water. A week after the nest is complete, females lay 1 to 4 eggs that vary in color from cream to brown, blue, or green. Eggs are incubated for 23 to 26 days and incubation duties are shared by both parents. Chicks are semiprecocial at hatching, which means they are covered in downy feathers but cannot open their eyes for several hours. Hatchlings remain in the nest until they are 20 to 30 days old. At this young age, chicks spend a lot of time swimming in the vicinity of the nest. Chicks develop flight feathers after 30 days and will fledge (leave the nest and fly) at 32 to 35 days old. After fledging, parents and their young remain together for an additional 8 to 10 days at which time the young become independent. Juveniles become reproductively mature at 2 years old. (Burger and Gochfeld, 2009)
In most pairs, both the male and female participate in building a nest of floating vegetation. Males that do not attract females after 1 to 2 weeks after establishing territory will begin to construct a nest alone. Both parents take turns incubating the eggs. Parents are for their chicks constantly after hatching, but this care gradually decreases after 8 to 10 days. Both parents gather and regurgitate food for the young. The young consume mainly earthworms but also grubs and insects. Parents actively feed the young until a week after they begin to fly. Parents will clean up after their young by removing eggshells and feces and relocating the waste 5 meters away from the nest. These sanitary duties may minimize disease within the nest or make it more difficult for predators to smell the nest. (Burger and Gochfeld, 2009)
Franklin's gulls may live to be 9 to 9.4 years old in the wild. There is no known information for lifespan in captivity. The eggs and young are most vulnerable and common causes of mortality include exposure, drowning, or predation. Little data exists on causes of adult mortality. (Burger and Gochfeld, 2009; Clapp, et al., 1982)
Franklin's gulls are diurnal, migratory birds that spend nearly all of their lives on or near water. They are social birds that nests in colonies of 100 to 100,000 breeding pairs. During the non-breeding season, this species gathers in large, often mixed-species, flocks that will form dense roosting groups with only 50 to 200 cm between individuals. Since they live so close to water they are frequently bathing, which is usually a social event done in groups of 2 to 50. These large, noisy bathing events may last 15 to 20 minutes.
Franklin's gulls are agile and can perch on cattail stems and take flight from the water surface in a quick manner. This species spends more time on the wing than most gulls and exhibits aerial mobbing or diving to deter predators. When defending territory on the ground, Franklin's gulls will exhibit long calls, head tossing, chocking, upright oblique, escape patterns, or attacks. (Burger and Gochfeld, 2009)
During the breeding season, male Franklin's gulls establish territories and will defend a 4 to 5 m radius around the nest. Females also participate in defending the nesting territory. As the breeding season progresses, floating nests often drift and nest spacing decreases from 7 m to 2 or 3 m. During the non-breeding season, this social species often roosts in very dense groups with only 50 to 200 cm between individuals. (Burger and Gochfeld, 2009)
Compared other gull species, Franklin's gulls make significantly louder and more frequent calls. However, Franklin's gulls have few distinct calls. This species gives alarm calls to alert chicks, mates, and neighbors of potential threats. The most common call given is a long call which is used to deter predators, establish territory and attract females. Other types of calls include a call signaling they will be landing or a courtship call. Franklin's gulls use physical displays during courtship. After a male has attracted a female he turns his back to her, bows his head, and raises his white neck feathers to hide his black head. The female displays interest by reciprocating these behaviors and the two will alternate looking at each other and then turning their backs. Like most birds, Franklin's gulls perceive their environment through the senses of sight, sound, taste, smell and hearing. (Burger and Gochfeld, 2009)
Franklin's gulls have a diet that consists of earthworms, grasshoppers, midges, mollusks, fish refuse and sometimes seeds. These gulls are largely opportunistic feeders and will eat a variety of vegetation and animal foods as they are available. Franklin's gulls been spotted in dumps picking for food, but they are more often found in fields or wetlands. In fields, these gulls often follow tractors which disturb resting insects, making it easy for the gulls to snatch a meal in flight. Franklin's gulls can catch insects in their bills while flying. These gulls may also eat on the ground, and will wade in shallow water to find mollusks or walk through tall grass to find resting insects. Young gulls are fed almost exclusively regurgitated earthworms, but occasionally parents will provide insects as well. ("Franklin's Gull", 2004; Burger and Gochfeld, 2009)
Franklin's gulls build nests that float over the water, causing much of their predators to be aquatic or aerial. Types of predators vary depending on location. In Minnesota, predators include northern harriers, muskrats, or great horned owls. Predators to adult Franklin's gulls include peregrine falcons and pomarine jaegers. Other predators include black-crowned night-herons which will eat the eggs and young. There have been reports of mink killing up to 35 chicks in one night. (Burger and Gochfeld, 2009)
As both prey and predator, Franklin's gulls play an important role within their environment. These gulls consume large amounts of insects such as grubs and earthworms which if left unchecked, these insect populations may cause significant damage to local vegetation and soil. Adults, young, and eggs are food for local terrestrial and aerial predators. (Burger and Gochfeld, 2009)
There are no negative impacts of Franklin’s gulls on humans.
Franklin's gulls are mostly insectivorous and consume large quantities of pest species such as earthworms and grubs. If left unchecked, populations of these insects may degrade the quality of crops or lawns which would negatively impact human landowners. These gulls also consume fish refuse which may contribute to decomposition and reduce the spread of disease. (Burger and Gochfeld, 2009)
Conservation concern for Franklin's gulls varies geographically, as recent population trends have been increasing, decreasing, or stable across its range. In Oklahoma, the population was at 3 million in 1950, dropped to 15,000 in 1990, and then increased to 60,000 in 1991. In Manitoba there is no sign of a population decrease. British Columbia has seen an increase in the number of breeding pairs. Even though Franklin's gulls are of least concern on the IUCN Red List, efforts are being made to protect wetlands across its range. Franklin's gulls only breed in wetlands and are very sensitive to changes in water depth within these wetlands. Efforts should be made to monitor water levels and wetland quality to ensure this species has suitable breeding habitat. As migratory birds, Franklin's gulls are protected under the United States Migratory Bird Act which regulates any collection of adults, young, or eggs. (Burger and Gochfeld, 2009; "Franklin's Gull", 1998; )
Heidi Rudolph (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Rachelle Sterling (editor), Special Projects.
2006. National Geographic Complete Birds of North America. Washington D.C.: The National Geographic Society.
2004. "Franklin's Gull" (On-line). Accessed March 15, 2011 at http://sdakotabirds.com/species/franklins_gull_info.htm.
Great Basin Bird Observatory. 1998. "Franklin's Gull" (On-line). Accessed April 30, 2011 at http://www.gbbo.org/pdf/bcp/41_Franklin's%20Gull.pdf.
USGS. 2000. "Franklin's gull Larus pipixcan" (On-line). Accessed April 30, 2011 at http://www.mbr-pwrc.usgs.gov/id/framlst/i0590id.html.
Burger, J., M. Gochfeld. 2009. "Birds of North America Online" (On-line). Franklin's Gull (Leucophaeus pipixcan). Accessed April 30, 2011 at : http://bna.birds.cornell.edu/bna/species/116.
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Clapp, R., M. Klimkiewicz, J. Kennard. 1982. Longevity records of North American birds: Gaviidae through Alcidae. Journal of Field Ornithology, 53: 81-124, 125-208.
Dawson, W., A. Bennett, J. Hudson. 1976. Metabolism and thermoregulation in hatchling ring-billed gulls. The Condor, 78: 49-60.