Larus delawarensis

A medium-sized (19 inches) seagull, the Ring-billed Gull is most easily identified by its pale orange eye, yellow legs, and conspicuous black ring on its yellow bill. Winter and immature gulls of many species are notoriously difficult to identify as these birds may be splotched or streaked with brown on the head and breast. Male and female Ring-billed Gulls are similar to one another in all seasons. The Ring-billed Gull breeds across a large part of southern Canada and the northern United States. Most populations of this species are migratory, wintering along the coasts from British Columbia south to central Mexico in the west, from New England south to Florida in the east, in parts of the interior southeast, and around Great Salt Lake in Utah. Ring-billed Gulls occur throughout the year in parts of the Pacific Northwest and the Great Lakes. Ring-billed Gulls primarily breed on small sparsely-vegetated islands in northern lakes. In winter, this species is often present along sandy beaches, but may also be found inland on reservoirs or around garbage dumps. Ring-billed Gulls eat a variety of foods, including crustaceans, fish, carrion, garbage, and, occasionally, other birds. Ring-billed Gulls are most easily seen foraging for food along sandy beaches. In many coastal areas, this is one of the most common winter “seagulls,” and may be seen foraging for refuse and carrion on the beach, flying over the water and plunging in to catch fish, or floating on the water’s surface while catching fish with its bill. Ring-billed Gulls are primarily active during the day.

Threat Status: Least concern

North America; range extends throughout the Canadian Atlantic.

Ring-billed gulls are native to the Nearctic and Neotropical regions. They live across the northern United States and southern Canada. During winter they migrate to the southern United States, Mexico, and Central America. They are also found in Bermuda and Hawaii.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

N America; winters to s Mexico, Bahamas and Gr. Antilles.

Belgian Exclusive Economic Zone, Gulf of Maine, Gulf of Mexico, Irish Exclusive economic Zone, North America, North West Atlantic, Polish Exclusive Economic Zone, Portuguese Exclusive Economic Zone, Spanish Exclusive Economic Zone, United Kingdom Exclusive Economic Zone, Wimereux

The Ring-billed Gull breeds in the USA and Canada from in north California, east Washington and interior British Columbia, across the praire provinces, north mountains and plain states. Also from the Great Lakes east to the coast. It winters in the southern portion of its breeding range south to the Gulf Coast, Mexico, Central America, Greater and Lesser Antilles¹.

Ring-billed gulls range from southern Alaska to the north shore of the Gulf of St. Lawrence, to southern parts of Oregon and Colorado and northern New York. During the winter, it is found from British Columbia to Maine (including the Great Lakes and Maritime regions), then south to central California to southern Mexico to the Gulf Coast to Cuba. It is also found in Bermuda and Hawaii. This gull winters from southwestern British Columbia and Washington state to the Great Lakes region to Nova Scotia then southward.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: BREEDING: Washington to Manitoba, south to northeastern California, Colorado, South Dakota; north-central Ontario to Newfoundland, south to eastern Wisconsin, northern Illinois, northern New England and New Brunswick. Nonbreeders occur in summer north to central Alaska, southern Yukon, southern Mackenzie, and southeastern Keewatin, and south through wintering range. NON-BREEDING: coast from southern British Columbia to southern Mexico, rarely south to Costa Rica and Panama; southeastern Canada to Gulf coast, Bahamas, and Greater Antilles; interior from Great Lakes to central Mexico; frequently in low numbers in Hawaii. See Spendelow and Patton (1988) for information on distribution and abundance in coastal U.S., including the Great Lakes region.

Widespread throughout North America, south to Mexico, Bermuda and Cuba.

Ring-billed gulls are medium-sized birds. Males are slightly larger than females. They are about 50.2 cm long and weigh about 550 g. Females are about 46.9 cm long and weigh about 470 g. Males and females have a wingspan of about 127 cm.

The backs and shoulders of ring-billed gulls are pale bluish-gray, and the head is white. The wings are tipped in black with white spots. Underneath, ring-billed gulls are white. The legs and feet have a yellow or green color. There is a black ring around the bill.

Immature birds have different coloration. First year ring-billed gulls are white with brown flecks and very dark wing tips and tail. Second year gulls are more like the adults, but have a black-tipped tail. Nestlings have two color phases; some are smoky gray, while others are pink with white spots.

Ring-billed gulls may be confused with herring gulls. Herring gulls are larger and have thicker bills without the black ring.

Range mass: 300 to 700 g.

Range length: 43 to 54 cm.

Average wingspan: 127 cm.

Sexual Dimorphism: male larger

Average basal metabolic rate: 2.91742 W.

Ring-billed gulls are medium-sized gulls. Males are larger than females. They are 46 to 54 cm long (average 50.2 cm) and weigh 400 to 700 g (average 550 g). Females are 43 to 50 cm long (average 46.9 cm) and weigh 300 to 600 g (average 470 g). Adults of both sexes have a wingspan of approximately 127 cm.

The back and shoulders of ring-billed gulls are pale bluish-gray, and the head is white. The wings are tipped in black with evident white spots, and the belly is whitish.

Ring-billed gulls have yellowish or greenish legs and feet. Their most distinctive feature is a sharply defined narrow black band that encircles the bill.

Immature ring-billed gulls have different coloration than adults. First year birds are whitish with brown flecks and have very dark wing tips and tails. Second year birds are more like the adults, but have a black-tipped tail.

Chicks have two color phases; some are smoky gray, while others are buff with dark spots.

Ring-billed gulls may be confused with herring gulls (Larus argentatus). Herring gulls are larger and have a thicker bill that lacks a clearly defined black ring.

Range mass: 300 to 700 g.

Range length: 43 to 54 cm.

Average wingspan: 127 cm.

Sexual Dimorphism: male larger

Average basal metabolic rate: 2.91742 W.

Length: 45 cm

Weight: 566 grams

Length: 45-53 cm, Wingspan: 121-127 cm

Ring-billed gulls are often found along inland waterways and in open landscapes. They typically occur on beaches, open grasslands, and wet meadows. Their preference for open areas makes them well-suited to urban and suburban landscapes and they are often found on large, grassy lawns, parking lots, and in vacant land.

Habitat Regions: temperate ; saltwater or marine ; freshwater

Terrestrial Biomes: desert or dune

Aquatic Biomes: lakes and ponds; rivers and streams; coastal

Other Habitat Features: urban ; suburban

Habitat and Ecology

Systems

• Terrestrial
• Freshwater
• Marine

These birds frequent inland waterways. They may be found in areas with sandy ground where vegetation is sparse. They may also be found where there are rocks and concrete pieces, on pebble beaches, and sometimes in wet meadows. Their preference for open areas makes them well-suited to urban and suburban landscapes and they are often found on large, grassy lawns, parking lots, and in vacant land.

In western areas of the U.S., Ring-billed gull colonies tend to be found within a 36 km radius of small towns or agricultural areas. This is not necessarily the case in the eastern U.S. where their main food is fish.

Habitat Regions: temperate ; saltwater or marine ; freshwater

Terrestrial Biomes: desert or dune

Aquatic Biomes: lakes and ponds; rivers and streams; coastal

Other Habitat Features: urban ; suburban

Depth range based on 523 specimens in 1 taxon.
Water temperature and chemistry ranges based on 278 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 4.207 - 26.926
  Nitrate (umol/L): 0.071 - 4.522
  Salinity (PPS): 30.822 - 36.261
  Oxygen (ml/l): 4.642 - 7.729
  Phosphate (umol/l): 0.060 - 0.674
  Silicate (umol/l): 1.201 - 11.312

Graphical representation

Temperature range (°C): 4.207 - 26.926

Nitrate (umol/L): 0.071 - 4.522

Salinity (PPS): 30.822 - 36.261

Oxygen (ml/l): 4.642 - 7.729

Phosphate (umol/l): 0.060 - 0.674

Silicate (umol/l): 1.201 - 11.312
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Comments: Seacoasts, bays, estuaries, rivers, lakes, ponds, irrigated fields and plowed lands, cities, dumps. Nests rocky, sandy, and grassy islets or isolated shores, occasionally on marshy lands, often with other water birds; mainly at inland lakes. Nests usually placed in low vegetation. See Spendelow and Patton (1988) for additional information.

Lakes, bays, coasts, piers, dumps, plowed fields. Always near water.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Arrives in northern breeding areas April-May (Bent 1921). Nonbreeders widespread in summer, from Alaska and northern Canada south through wintering range (AOU 1983). Some, mostly first- or second-year birds, reach Central America, mainly early November-late May (Stiles and Skutch 1989).

Moves south in flocks for the winter.

Ring-billed gulls are opportunistic feeders, or scavengers, meaning they will eat almost anything that they find. They eat Actinopterygii, Rodentia, small aquatic animals, Aves, Insecta, and vegetable matter such as fruits, though they prefer animal foods.

This kind of feeding behavior has made them very successful in areas around humans where they take advantage of land fills, garbage dumps, and ships that dump garbage overboard. They also scavenge from plowed fields, parks, and parking lots. In fact, these gulls might be seen squabbling over discarded items from fast-food restaurants. Ring-billed gulls are able to snatch food from the water's surface while in flight.

Animal Foods: birds; mammals; fish; insects; terrestrial worms

Plant Foods: seeds, grains, and nuts; fruit

Ring-billed gulls are opportunistic feeders, or scavengers, meaning they will eat almost anything that they find. They eat fish, rodents, small aquatic animals, bird chicks and eggs, insects, and vegetable matter such as fruits, though they prefer animal foods.

This kind of feeding behavior has made them very successful in areas around humans where they take advantage of land fills, garbage dumps, and ships that dump garbage overboard. They also scavenge from plowed fields, parks, and parking lots. In fact, these gulls might be seen squabbling over discarded items from fast-food restaurants. Ring-billed gulls are able to snatch food from the water's surface while in flight.

Animal Foods: birds; mammals; fish; insects; terrestrial worms

Plant Foods: seeds, grains, and nuts; fruit

Primary Diet: omnivore

Comments: Feeds opportunistically on various animals and plant material (and garbage), usually obtained from land or water surface; sometimes catches flying insects and pulls fruits from shrubs and trees.

Insects, fish, earthworms, grain, rodents, garbage.

Ring-billed Gulls are scavengers, so they often consume foods that would otherwise go to waste. They affect the populations of the animals they prey upon. They also support the populations of small predators that prey on them.

Ring-billed gulls compete with other gull species for food and have been observed stealing food from Sturnus vulgaris.

Predators of ring-billed gulls include Vulpes vulpes, Canis latrans, Mephitis mephitis, Procyon lotor, Mustela frenata, Mustela vison, Larus californicus, Larus argentatus, Bubo virginianus, Nyctea scandiaca, Corvus brachyrhynchos and Corvus corax.

Ring-billed gulls swoop and soar above predators to drive them away. They also mob predators by attacking them in groups. Because ring-billed gulls nest and feed in large colonies, they depend on each other to detect predators. The alarm calls and panic flights of neighbors let other birds in colony know that a predator is nearby.

Known Predators:

• red foxes (Vulpes_vulpes)
• coyotes (Canis_latrans)
• striped skunks (Mephitis_mephitis)
• raccoons (Procyon_lotor)
• long-tailed weasels (Mustela_frenata)
• American minks (Mustela_vison)
• California gulls (Larus_californicus)
• herring gulls (Larus_argentatus)
• great horned owls (Bubo_virginianus)
• snowy owls (Nyctea_scandiaca)
• American crows (Corvus_brachyrhynchos)
• common ravens (Corvus_corax)

Ring-billed Gulls are scavengers, so they often consume foods that would otherwise go to waste. They affect the populations of the animals they prey upon. They also support the populations of small predators that prey on them.

Ring-billed gulls compete with other gull species for food and have been observed stealing food from starlings.

Predators of ring-billed gull adults, chicks and eggs include red fox, coyote, striped skunk, raccoons, long-tailed weasel, mink, California gulls, herring gulls, great horned owls, snowy owls, American crows and common ravens.

Ring-billed gulls respond to predators by swooping and soaring above them, and mobbing them in small groups. Because ring-billed gulls nest and feed in large colonies they rely on each other to detect predators. The alarm calls and panic flights of colony members alert others to the presence of predators.

Known Predators:

• red foxes (Vulpes vulpes)
• coyotes (Canis latrans)
• striped skunks (Mephitis mephitis)
• raccoons (Procyon lotor)
• long-tailed weasels (Mustela frenata)
• American minks (Neovison vison)
• California gulls (Larus californicus)
• herring gulls (Larus argentatus)
• great horned owls (Bubo virginianus)
• snowy owls (Nyctea scandiaca)
• American crows (Corvus brachyrhynchos)
• common ravens (Corvus corax)

Larus delawarensis preys on:
Pagurus
Pagurus maclaughlinae
Libinia dubia
Pinixia floridana
Neopanope texana
Callinectes sapidus
Processa bermudiensis
Penaeus duoarum
Palaemonetes floridanus
Anchoa mitchilli
Menidia beryllina
Laridae
Cyprinodon variegatus
Carassius auratus
Pimephales notatus

Based on studies in:
USA: Florida (Estuarine)

This list may not be complete but is based on published studies.

Fox predation may result in reproductive failure of local breeding colonies (Southern et al. 1985). May prevent terns from nesting by usurping habitat. Breeding individuals foraged an average of 11 km from colony (Baird 1977).

Ring-billed Gulls communicate using calls and body language. They have two alert calls; a screeching call that sounds like "kree, kree" and a shrill "kyow kyow kyow " call that sounds high-pitched and squealing. They use a "mew" call during breeding activities, such as courtship feeding and feeding chicks.

While being aggressive, ring-billed gulls lower their head to their feet and then toss their head backward at the end of a call. When they are being submissive, they hunch their head and neck and make short, high-pitched "klioo" calls while tossing their head.

Communication Channels: visual ; acoustic

Ring-billed Gulls primarily communicate using calls and body language. They have two alert calls; a screeching call that sounds like "kree, kree" and a shrill "kyow kyow kyow " call that sounds high-pitched and squealing. A "mew" call is used during courtship feeding, feeding of chicks, and other non-aggressive types of behavior. The long call is given during hostile displays and landing.

While engaging in aggressive behaviors, ring-billed gulls lower their head to their feet, then toss their head backward before ending a long call. During submissive displays, they draw in their head and neck in a hunched fashion, sounding short, high-pitched "klioo" notes and engaging in head tossing.

Communication Channels: visual ; acoustic

Ring-billed gulls have been recorded living as long as 23 years in the wild. However, it is likely that the majority of these birds live much shorter lives than this, probably 3 to 10 years.

Range lifespan
Status: wild: 23 (high) years.

Typical lifespan
Status: wild: 3 to 10 years.

Ring-billed gulls have been recorded living as long as 23 years in the wild. However, it is likely that the majority of these birds live much shorter lives than this, probably 3 to 10 years.

Range lifespan
Status: wild: 23 (high) years.

Typical lifespan
Status: wild: 3 to 10 years.

Maximum longevity: 31.8 years (wild) Observations: In the wild, most animals do not live more than 5 years (John Terres 1980).

Ring-billed gulls are monogamous (one male mates with one female). Males and females for breeding pairs just before arriving on the breeding grounds, or just after arriving. Occasionally, two females mate with one male. This is called polygyny.

Mating System: monogamous ; polygynous

Ring-billed gulls nest in colonies on the ground, or sometimes in trees near lakes. They often nest near other water birds. The male and female work together to build the nest out of twigs, sticks, grasses, leaves, lichens and mosses.

The female lays three eggs. Each is about 6.4 cm long by 4.6 cm wide. The eggs are light blue, green or brownish and spotted. The male and female both incubate the eggs for about 20 to 31 days. After the chicks hatch, both parents brood and feed them. The chicks begin leaving the nest within days of hatching, and are able to fly at about 5 weeks old.

Ring-billed gulls breed between May and August. They probably do not begin breeding until they are at least 2 years old.

Breeding interval: Ring-billed gulls breed once per year.

Breeding season: Ring-billed gulls breed between May and August.

Range eggs per season: 2 to 4.

Range time to hatching: 20 to 31 days.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average eggs per season: 3.

Both parents incubate the eggs and feed nestlings until they reach independence. The young remain in the nest until they are able to walk, at about 4 days old. Birds depart from the nesting area immediately upon fledging, at about 45 days old.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female)

Ring-billed gulls are generally monogamous. Breeding pairs form immediately before or during arrival on the breeding grounds and territory establishment. In expanding colonies, polygynous trios (two females attending the same nest and mated to the same male) are frequently observed.

Mating System: monogamous ; polygynous

Ring-billed gulls nest in colonies on the ground, or infrequently, in trees near inland lakes. Nests are built by both members of a breeding pair. Nests are constructed of dead plant material including twigs, sticks, grasses, leaves, lichens and mosses, and may be interspersed with those of other water birds.

The female lays 2 to 4 (usually 3) eggs per clutch, each about 6.4 cm long by 4.6 cm wide. The eggs are light blue, green or brownish and spotted. Both male and female incubate the eggs. The semiprecocial chicks hatch after 20 to 31 days, and are brooded and fed by both parents. The chicks begin leaving the nest within days of hatching, and are able to fly at about 5 weeks old.

Ring-billed gulls breed between May and August. The age at first breeding is not known, but is probably at least two years.

Breeding interval: Ring-billed gulls breed once per year.

Breeding season: Ring-billed gulls breed between May and August.

Range eggs per season: 2 to 4.

Range time to hatching: 20 to 31 days.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average eggs per season: 3.

Both parents incubate the eggs and feed nestlings until they reach independence. The young remain in the nest until they are able to walk, at about 4 days old. Birds depart from the nesting area immediately upon fledging, at about 45 days old.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female)

Eggs are laid in May-June. Clutch size usually is 3. Incubation, by both sexes, lasts about 21 days. Young are tended by both parents, fed until able to fly. Usually attains adult plumage in 3 years. May form female-female pairs or polygynous trios.

Breeds in colonies, nesting near water on the ground. 2-4 eggs incubated by both sexes 23-28 days. Females sometimes share nests. Young are fed by both parents. First flight around 5 weeks old, independent of parents a week or so later.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 3 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 3
Specimens with Barcodes: 8
Species With Barcodes: 1

Ring-billed Gull populations are not threatened. Population sizes may have increased in recent historical times because ring-billed gulls benefit from human activities, such as landfills and fishing practices.

They are protected under the U.S. Migratory Bird Treaty Act as migratory birds.

IUCN Red List of Threatened Species: least concern

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Least Concern
• 2004
  Least Concern

Ring-billed Gull populations are not threatened. Population sizes may have increased in recent historical times because ring-billed gulls benefit from human activities, such as landfills and fishing practices.

They are protected under the U.S. Migratory Bird Treaty Act as migratory birds.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

United States

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

Rounded Global Status Rank: G5 - Secure

No official conservation status.

Management Requirements: See Smith (1986) and Blokpoel and Tessier (1986) for useful overview and annotated bibliography pertaining to management. See Griffin and Hoopes (1992) for gull management recommendations for JFK International Airport in New York. The need in some areas for gull control has been debated (see Morris and Siderius 1990).

Two applications of light-grade commercial petroleum oil to gull eggs reduced hatchability to zero; adults continued to incubate the eggs for more than 6 weeks beyond the expected hatching time and did not renest that year (Morris and Siderius 1990); similar results using nontoxic white mineral oil were reported by Blokpoel and Hamilton (1990) and Christens and Blokpoel (1991).

Some people consider large groups of these birds to be pests due to their droppings, garbage stealing, and the noise that they create.

Ring-billed gulls often eat garbage created by humans, which helps reduce waste.

Some people consider large groups of these birds to be pests due to their droppings, garbage stealing, and the noise that they create.

Ring-billed gulls often eat garbage created by humans, which helps reduce waste.

Comments: Becoming a potentially serious agricultural and urban-suburban nuisance species. Sometimes a hazard to aircraft near airports.