Wyoming’s landscape of arid plains, lakes and rivers attracts an impressive diversity of gull species, from small delicate migrants to large, bold coastal visitors. Prepare to identify these masters of flight as they traverse the Cowboy State! Their varied shapes and sizes showcase a range of survival adaptations honed over millennia. Watch for their aerial acrobatics and sharp cries that evoke the spirit of wilderness. Whether gliding gracefully or competing for scraps, gulls embody freedom, resilience and opportunism. From common year-round residents to rare vagrants, gulls provide unlimited opportunities to appreciate avian diversity across Wyoming’s skies. Let’s explore how to identify the state’s 8 most widespread gull types.
| Gull Type | Size | Distinctive Features |
|---|---|---|
| Ring-billed Gull | Medium – 50 inch wingspan | Yellow bill with black ring, gray back, black wingtips with white spots |
| California Gull | Medium – 55 inch wingspan | Gray back, bold black & white pattern on flight feathers |
| Franklin’s Gull | Small – 33 inch wingspan | Black head, white eyering, red bill |
| Bonaparte’s Gull | Small – 33 inch wingspan | Black hood, red bill and legs, narrow pointed wings |
| Herring Gull | Large – 65 inch wingspan | Pale grey back, yellow bill with red spot, pink legs |
| Caspian Tern | Very large – 55 inch wingspan | Black cap, long orange dagger-like bill |
| Sabine’s Gull | Medium – 42 inch wingspan | Black hood, yellow-tipped black bill, bold black & white pattern on upperwings |
| Mew Gull | Small – 42 inch wingspan | Yellow bill with red spot and black tip, delicate flight |
Table of Contents
1. Ring-Billed Gull
The ring-billed gull (Larus delawarensis) is one of the most common gulls found in Wyoming. With a wingspan of around 50 inches, it is a medium-sized gull with a white head, light gray back and wings, black wingtips with white spots, and yellow legs and feet. The ring-billed gull gets its name from the black ring around its yellow bill.
This gull breeds in the northern US and Canada, wintering along coastlines further south. In Wyoming, ring-billed gulls can be seen near lakes, rivers, and landfills across the state during summer. They often gather in large flocks and will scavenge for food in parking lots and recreational areas. Their diet consists mainly of small fish, aquatic invertebrates, eggs and chicks of other birds, grain, earthworms, and garbage.
Ring-billed gulls are opportunistic feeders and will readily adapt to take advantage of human food sources. They have a sharp, loud call that sounds like a laughing “kree-ah.” During the breeding season, ring-billed gulls build nests of vegetation on the ground near water. The female typically lays around 3 eggs which hatch after about 4 weeks. The chicks are able to fly at around 5 weeks old but remain with the parents for another 3-4 weeks to continue developing their flying and foraging skills.
This adaptable gull continues to thrive across its range despite declining populations of other gull species. However, ring-billed gulls may face threats from pollutants, habitat loss, and disturbances to breeding colonies. They are protected under the Migratory Bird Treaty Act in the US. Observing ring-billed gulls in Wyoming can be a good way to study the behavior of these resourceful birds.
2. California Gull
The California gull (Larus californicus) is a medium-sized gull named after the state where it was first discovered in the 1860s. In Wyoming, California gulls can be found across the state during the breeding season, especially in colonies around Yellowstone National Park and the Seedskadee National Wildlife Refuge.
Adult California gulls have gray upperparts, white underparts, yellow legs, and a long yellow and green bill. Their wings are gray with bold black and white markings on the flight feathers. Juveniles start out mottled brown before reaching adult plumage by their second year. These gulls reach lengths of 19-22 inches with wingspans around 55 inches.
The diet of California gulls consists mainly of insects, fish, rodents, eggs, grains and human food waste. They forage in both terrestrial and aquatic habitats. Their loud call sounds like a repeated “kee-ah.” During the breeding season, nests are built on the ground and consist of grasses, sticks and feathers. Females usually lay 2-3 eggs that hatch after around 3 weeks.
California gulls form large breeding colonies that can number in the thousands of pairs. They are migratory, wintering along the Pacific Coast and as far south as Mexico. Conservation threats include disturbance to nesting colonies, pollution, habitat loss and declining food sources. However, their populations remain relatively stable.
Observing California gulls flying gracefully along Wyoming’s lakes and rivers can be an enjoyable part of the state’s wildlife viewing opportunities. These gulls are very adaptable and their survival speaks to their resilient nature.
3. Franklin’s Gull
With its striking black hood and red bill, the Franklin’s gull (Leucophaeus pipixcan) is a small but distinctive species of gull that can be found in Wyoming during its spring and fall migrations. This gull breeds in the prairie wetlands of central North America and winters along the Pacific and Gulf Coasts.
In their adult plumage, Franklin’s gulls have a black head, white eyering, gray back and wings, white underparts and bright red legs and bill. Their wings appear mostly white in flight with black wingtips. Juveniles are mottled brown and gray. These small gulls reach lengths of only 13-15 inches with wingspans around 33 inches.
Franklin’s gulls feed primarily on insects, picking them off the surface of water and grasslands. They also eat aquatic invertebrates, fish, frogs, seeds and grain. Their slender bills are well-adapted for picking small prey. In flight, they have a graceful, buoyant glide and swiftly twisting maneuvers.
During migrations, Franklin’s gulls can be seen in Wyoming at lakes, reservoirs, rivers and wetlands across the eastern and central parts of the state. They often stop to rest and feed in large flocks numbering in the hundreds or thousands of individuals. Their high-pitched call sounds like a laughing “kee-wee-wee.”
Breeding occurs in large colonies in marshy areas from prairie Canada through the northern Great Plains. Nests consist of floating mats of vegetation anchored in shallow water. Franklin’s gulls are aerial acrobats that prefer nesting over water safe from predators. Seeing a flock of these small, agile gulls in Wyoming can be a delight for bird enthusiasts during the migration seasons.
4. Bonaparte’s Gull
With its dainty appearance and graceful flight, the Bonaparte’s gull (Chroicocephalus philadelphia) is a regular migratory visitor across Wyoming. This small gull breeds in boreal forest areas of Canada and Alaska and winters along ocean coastlines and large inland lakes.
Adult Bonaparte’s gulls are distinctive with their black hood, white wings and body, and red bill and legs. In flight, their narrow, pointed wings show a bold black and white pattern. They have a length of just 13-14 inches and wingspan around 33 inches. Juveniles start out mottled brown before molting to adult plumage by their second year.
This gull gets its common name from Charles Lucien Bonaparte, a French ornithologist and nephew of Napoleon Bonaparte. It feeds primarily on insects and other small invertebrates picked off the water’s surface in a series of graceful dips and skims.
During migration, Bonaparte’s gulls pass through Wyoming and can be observed near lakes, reservoirs and rivers across the state, often in flocks numbering hundreds of individuals. They have a high-pitched, twittering call most frequently heard during flight.
Breeding occurs near small ponds, bogs and streams in northern wilderness forests. Their floating nests are built from vegetation anchored to logs, islands or overhanging bushes. Bonaparte’s gulls are aerial foragers that excel at catching insects on the wing. Seeing them in Wyoming helps birdwatchers appreciate the journeys of these delicate yet hardy migrants.
5. Herring Gull
With its large size, grey back, white head and underparts, and pink legs, the herring gull (Larus argentatus) is one of the most familiar gulls in the Northern Hemisphere. In Wyoming, herring gulls are uncommon but regular winter visitors, especially along the eastern border of the state.
These large gulls have a length of around 25 inches and wingspan of up to 65 inches. Adults have pale grey backs, black wingtips with white spots, and yellow eyes with red rings. Their large yellow bills are hooked at the end with a reddish spot near the tip. Juveniles are mottled brown before reaching adult plumage by their fourth year.
Herring gulls are opportunistic, generalized feeders that eat a variety fish, invertebrates, seabird eggs and chicks, small mammals, worms, insects, grains, berries, and garbage. They often drop hard-shelled prey from heights to crack them open. Their familiar loud, laughing calls are well-known in coastal habitats.
This species breeds in colonies across subarctic and temperate coastal regions of the Northern Hemisphere. Nests consist of scrapes lined with vegetation and are aggressively defended from predators and other gulls. Most Wyoming sightings occur during winter near reservoirs, landfills, and along major rivers.
While herring gull numbers are declining in parts of their range, they have shown an ability to adapt to human habitats and exploit new food sources. Seeing herring gulls in Wyoming can offer a taste of their marine origins and showcase their survival skills in a variety of environments. Their large size and piercing calls are key identification cues.
6. Caspian Tern
With its large crimson bill and harsh, piercing calls, the Caspian tern (Hydroprogne caspia) ranks as the largest tern in the world. This far-flying seabird can be seen in Wyoming mainly during the fall migration period as lone individuals or small groups. They breed in major colonies along the North American coastlines and interior areas nearby large lakes and marshes.
Adult Caspian terns have black caps, white faces, and reddish-orange long, dagger-like bills. Their upperparts are pale gray, and underparts white with limited black on the leading edge of the wing. In flight, their long, slender wings show thin, pointed black tips and a conspicuous white trailing edge to the secondaries. They have a wingspan reaching around 55 inches.
These huge terns feed mainly on small fish caught by diving from heights of up to 30 feet. They also take crustaceans, insects, amphibians and even voles and young gulls. Caspian terns utilize their specially adapted bills to grasp slippery prey items. They often rob food from other seabirds as well. Their loud, raucous calls are distinct and carry long distances.
Most Wyoming sightings occur as Caspian terns pass through the state in the fall, stopping briefly to rest and feed at lakes, reservoirs and rivers. They once bred sparingly in Wyoming until the early 1900s. While their continental populations are stable, habitat loss threatens some coastal breeding colonies. Seeing a Caspian tern in Wyoming provides an encounter with one of the avian world’s most impressive fishing specialists.
7. Sabine’s Gull
With its graceful tern-like flight and striking plumage pattern, Sabine’s gull (Xema sabini) is one of Wyoming’s most prized vagrant bird sightings. This circumpolar Arctic breeder typically winters at sea in the Southern Hemisphere. Most Wyoming records occur during the fall migration period when a few individuals stray inland after getting caught up in storms or frontal systems.
The adult Sabine’s gull is unmistakable with a black hood, yellow-tipped black bill, white triangular tail, and bold black and white pattern on the upperwings. The underwings form a dramatic diagnostic pattern with black at the tips blending to gray and then white. Juveniles are mostly brownish-gray with some white mottling.
This unique gull feeds by dipping and surface plunging primarily for small fish, but also eats krill, insects and other invertebrates. They display tern-like aerial agility when foraging. Sabine’s gulls breed colonially on Arctic coastal tundra in elaborate mud-cup nests lined with vegetation. Their eerie, mournful calls carry long distances.
Most records in Wyoming occur at locations across the eastern half of the state during September and October as lone juveniles or adults. Birders considering this gull a prize sighting due to its pelagic habits and association with Arctic landscapes very different from Wyoming. Seeing one provides birdwatchers a chance connection with the remote north.
8. Mew Gull
The mew gull (Larus canus) is a small-sized gull that breeds across northern Eurasia and North America. In Wyoming, this species occurs only as a rare vagrant visitor typically during spring and fall migrations. Adult mew gulls in breeding plumage have white heads, pale gray backs, white underparts and yellow legs. Their bill is greenish-yellow with red spot and black tip. In winter, their heads are streaked brownish gray. Juveniles appear mottled brown and take several years to reach full adult plumage.
These gulls reach lengths of 16-18 inches with wingspans around 42 inches. They are slightly smaller than the ring-billed gull. Mew gulls eat a variety of prey including marine invertebrates, fish, insects, worms, grains and berries. They have a delicate and graceful flight style, more like a tern. Their nasal call sounds like a cat-like “mewing.”
During the breeding season, mew gulls build nests on coastal cliffs, islands, and in marshy areas across the Arctic and subarctic regions. Most sightings in Wyoming occur at locations in the eastern part of the state during the spring and fall migration periods. Seeing a mew gull in Wyoming allows birdwatchers a chance to observe a species associated with the open Arctic regions of the north. Their occurrence indicates some were blown off course during the long migrations between the continents.