A large (19-23 inches) tern, the Caspian Tern in summer is most easily identified by its gray-tipped wings, black cap, and large orange bill. In winter, the black in this species’ cap is replaced by mottled gray. Male and female Caspian Terns are similar to one another in all seasons. The Caspian Tern inhabits every continent except Antarctica. In North America, this species breeds locally in central Canada, the Great Lakes, along the Gulf coast of the United States, and along the Pacific and Atlantic coasts of the U.S.and Canada. In winter, Caspian Terns may be found in southern California, along the coast of the southeastern U.S., and further south into Mexico and Central America. In the Old World, this species breeds in Eurasia from Eastern Europe east to China, along the coasts of Africa and South Asia, and in Australasia, wintering widely in the tropics. Caspian Terns breed in a variety of habitats, including marshes, estuaries, barrier islands, bays, and lakes, and may be found either in freshwater or in saltwater. In winter, this species utilizes similar habitat types as in summer. Caspian Terns primarily eat fish and small crustaceans. Caspian Terns may be most easily seen standing or walking along the shore or on the beach, where their large size and bright orange bill are most apparent. With the aid of binoculars, it may also be possible to observe this species feeding by diving headfirst into the water. Caspian Terns are most active during the day.

Threat Status: Least concern

Caspian terns have a cosmopolitan distribution, they are found on all continents except Antarctica. They are found along coastlines of oceans, seas, large lakes, and rivers. They migrate between breeding and wintering ranges for the most part, although some populations are resident year-round.

In the Americas, Caspian terns breed along coastal and inland waterways from the Gulf of Mexico and Baja California northwards through the Great Lakes and Canadian interior and as far north as southern Alaska on the Pacific coast and the Canadian maritime provinces on the Atlantic coast. They winter from southern California to Guatemala along the Pacific coast, including the Gulf of California, and from southern North Carolina on the Atlantic coast to Panama and Venezuela, including the Gulf of Mexico. They also winter in the Antilles.

Caspian terns breed in coastal areas from Scandinavia to the Baltic and Black Seas, throughout central Asia to Mongolia and the Persian Gulf and Red Sea to southeast Asia. They also breed throughout Australasia and Africa. Winter ranges are in warmer areas of their breeding range, including the Baltic, Black, and Mediterranean Seas, the Persian Gulf, and along African coastlines to South Africa.

Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native ); oceanic islands (Native )

Other Geographic Terms: cosmopolitan

Caspian terns have a cosmopolitan distribution, they are found on all continents except Antarctica. They are found along coastlines of oceans, seas, large lakes, and rivers. They migrate between breeding and wintering ranges for the most part, although some populations are resident year-round. In the Americas, Caspian terns breed along coastal and inland waterways from the Gulf of Mexico and Baja California northwards through the Great Lakes and Canadian interior and as far north as southern Alaska on the Pacific coast and the Canadian maritime provinces on the Atlantic coast. They winter from southern California to Guatemala along the Pacific coast, including the Gulf of California, and from southern North Carolina on the Atlantic coast to Panama and Venezuela, including the Gulf of Mexico.

Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native ); oceanic islands (Native )

Other Geographic Terms: cosmopolitan

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

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) BREEDS: Eastern U.S.: locally on Atlantic and Gulf coasts, from Virginia to northern Florida (very few), also recently in New Jersey, on the central Gulf Coast of Florida, and in southeastern Louisiana, Alabama, Mississippi, and Texas; and around the Great Lakes. Canada: Labrador, southeastern Quebec, and Newfoundland; Great Lakes region in southern Ontario; southern Manitoba and central Saskatchewan, along shores of Lake Winnipeg, Lake Winnepegosis, and Dore Lake; in Lake Athabasca in northeastern Alberta; and vicinity of Great Slave Lake in southern Mackenzie. In western North America: locally (mostly in interior but on coast in Washington and California) in Washington, eastern Oregon, northern Utah, northwestern Wyoming, Idaho (recent range expansion), and North Dakota, south to southern California and western Nevada; also Baja California and Sinaloa. WINTERS: southern U.S. (mainly coastal areas north to California and North Carolina) south to Mexico; sometimes to northern South America (Colombia, Venezuela), rarely in the West Indies. Casual in Hawaii. Breeds and winters extensively also in the Old World (Africa, Eurasia, Australian region).

Caspian terns are the largest tern species and are recognized by their large, bright coral red bill and full black cap on the head. Sexes are alike, from 47 to 54 cm long and from 530 to 782 g. Their upperparts are smooth gray and their breast, belly, rump, and tail are white. The wing feathers are dark gray to black on the underside. Their black cap might be speckled with white during the non-breeding season and in juveniles. The tail is only slightly notched. They have a large bill that is deep red to orange, sometimes with dark gray mark at the tip.

Range mass: 530 to 782 g.

Range length: 47 to 54 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

Caspian terns are the largest tern species and are recognized by their large, bright coral red bill and full black cap on the head. Sexes are alike, from 47 to 54 cm long and from 530 to 782 g. Their upperparts are smooth gray and their breast, belly, rump, and tail are white. The primary feathers are dark gray to black on the underside. Their black cap extends to below the eye and onto the back of the head, it can become speckled with white during the non-breeding season and in juveniles. The tail is only slightly notched. They have a robust bill that is deep red to orange, sometimes with dark gray mark at the tip. Caspian terns are distinguished from other terns by their large size, substantially larger than most terns and about the size of gulls.

Range mass: 530 to 782 g.

Range length: 47 to 54 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

Length: 53 cm

Weight: 661 grams

Differs from most other terns in much larger size and much thicker bill. Differs from the somewhat smaller royal tern in having a thicker bill, more extensive dark coloration on the underside of the primaries, and a less deeply forked tail; lacks the white forehead that is present in immature and basic plumages of royal and elegant terns.

Caspian terns are found in coastal areas, including beaches, marshes, estuaries, or in open habitats on islands in large bodies of water. They forage over water and nest on sandy, muddy, or pebbly shores or areas with little vegetation on islands.

Habitat Regions: temperate ; tropical ; terrestrial ; saltwater or marine

Terrestrial Biomes: desert or dune

Aquatic Biomes: coastal

Other Habitat Features: estuarine

• Terrestrial
• Freshwater
• Marine

Caspian terns are found in coastal habitats, including beaches, marshes, estuaries, or in open habitats on islands in large bodies of water. They forage over water and nest on sandy, muddy, or pebbly shores or areas with little vegetation on islands. Nesting on islands minimizes risks of predation to eggs and nestlings. They migrate along similar habitats as in their wintering and breeding ranges.

Habitat Regions: temperate ; tropical ; terrestrial ; saltwater or marine

Terrestrial Biomes: desert or dune

Aquatic Biomes: coastal

Other Habitat Features: estuarine

Comments: Seacoasts, bays, estuaries, lakes, marshes, and rivers.

Nests on sandy or gravelly beaches and shell banks along coasts or large inland lakes; sometimes with other water birds. Pacific coast populations formerly nested mainly in inland marshes, now mainly on human-created habitats (e.g., salt pond dikes and levees) along coast; nests on dredge-spoil islands in North Carolina and Florida. See Spendelow and Patton (1988) for further details. In northeastern Lake Michigan, tended to use same colony site in successive years unless previous reproductive effort was unsuccessful (Cuthbert 1988).

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.

Juveniles in western North America disperse northward before migrating south to wintering areas, remain in wintering area through second winter, thereafter make annual migrations between breeding and wintering areas (Gill and Mewaldt 1983).

Great Lakes population winters along shores of Gulf of Mexico (Evers 1992).

Caspian terns eat mainly fish, with some crayfish and insects occasionally. They forage by flying above shallow water, usually along a shoreline. As most Sterna do, they fly with their heads down, peering into the water, when they see prey, they may hover for a moment before making a sharp dive. They may just skim the surface when they dive or they may almost completely submerge themselves for a few seconds. They usually eat their prey as soon as it is captured but may take some fish back to a nest. They may wash fish before offering it to young and often clean their bill in water after feeding young. Fish prey includes Cymatogaster aggregata, Engraulis mordax, Alosa pseudoharengus, Osmerus mordax, Perca flavescens, Amblopites rupestris, Atherinopsis californiensis, Atherinops affinis, Leptocottus armatus, and juvenile Oncorhynchus.

Animal Foods: fish; insects; aquatic crustaceans

Caspian terns eat primarily fish, with some crayfish and insects taken occasionally. They forage by flying above shallow water (0.5 to 5 m deep) at heights of 3 to 30 m, usually along a shoreline. As most terns do, they fly with their heads down, peering into the water, when they see prey, they may hover for a moment before making a sharp dive. They may just skim the surface when they dive or they may almost completely submerge themselves for a few seconds. They usually eat their prey as soon as it is captured but may take some fish back to a nest. They may wash fish before offering it to young and often clean their bill in water after feeding young. Dominant fish prey varies regionally, but includes shiner perch (Cymatogaster aggregata), anchovies (Engraulis mordax), alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax), yellow perch (Perca flavescens), rock bass (Amblopites rupestris), jacksmelt (Atherinopsis californiensis), topsmelt (Atherinops affinis), staghorn sculpin (Leptocottus armatus), and juvenile salmon (Oncorhynchus).

Animal Foods: fish; insects; aquatic crustaceans

Primary Diet: carnivore (Piscivore )

Comments: Eats mainly fishes obtained at surface of water by diving from air; sometimes feeds from surface like a gull and eats eggs and young of other terns and gulls (Terres 1980).

Caspian terns are predators of small or young fish in coastal areas, they may be especially important predators in areas near breeding colonies. Caspian terns must compete for limited nesting habitats, including competing with Larus species. Caspian terns are parasitized by lice and internal worms.

Mutualist Species:

• western gulls (Larus_occidentalis)
• glaucous-winged gulls (Larus_glaucescens)
• herring gulls (Larus_argentatus)

Commensal/Parasitic Species:

• nematode (Cosmocephalus species)
• lice (Actornithophilus_funebre)
• lice (Degeeriella_praestans)
• lice (Menophon)
• lice (Philopterus_melanocephalus)
• cestodes (Dibothriocephalus_oblongatum)
• cestodes (Schistocephalus_solidus)
• cestodes (Paricterotaenia species)
• trematodes (Diplostomum species)
• trematodes (Cotylurus species)
• trematodes (Ornithobilharzia species)
• trematodes (Clinostomum species)
• trematodes (Stephanoprora species)

Most predation is on eggs and hatchlings, which may be taken by a wide variety of predators. Reported predators on eggs and hatchlings include Larus, Bubo virginianus, Corvus corvax, Felis catus, Canis lupus familiaris, Canis latrans, Vulpes vulpes, Mephitis mephitis, Procyon lotor, Esox lucius, and Crotalus atrox. Adult Caspian terns may fall prey to birds of prey, such as Haliaeetus leucocephalus, and terrestrial predators when roosting or on a nest, such as Canis latrans and Vulpes vulpes. When a predator approaches a nesting colony, Caspian terns raise an alarm call and will often join together to mob the predator. They are aggressive and will chase any large bird that is close to a colony. Their diving attacks can be very effective, resulting in bloody wounds. However, their habit of taking flight to mob a predator may also leave eggs and nestlings vulnerable. Predators sometimes grab eggs and nestlings from exposed nests when the adults have flown away. Chicks crouch in the nest scrape and difficult to see, but will be detected by predators using scent or warmth to find prey.

Known Predators:

• gull species (Larus)
• great horned owls (Bubo_virginianus)
• common ravens (Corvus_corvax)
• domestic cats (Felis_catus)
• dogs (Canis_lupus_familiaris)
• coyotes (Canis_latrans)
• red foxes (Vulpes_vulpes)
• striped skunks (Mephitis_mephitis)
• raccoons (Procyon_lotor)
• northern pike (Esox_lucius)
• western diamondback rattlesnakes (Crotalus_atrox)
• bald eagles (Haliaeetus_leucocephalus)

Anti-predator Adaptations: cryptic

Caspian terns are predators of small or young fish in coastal areas, they may be especially important predators in areas near breeding colonies. Caspian terns must compete for limited nesting habitats, including competing with gull species (Larus occidentalis, Larus glaucescens, and Larus argentatus). Parasites of Caspian terns include lice (Actornithophilus funebre, Degeeriella praestans, Menophon, and Philopterus melanocephalus) and cestodes (Dibothriocephalus oblongatum, Schistocephalus solidus, and Paricterotaenia species), trematodes (Diplostomum, Cotylurus, Ornithobilharzia, Clinostomum, and Stephanoprora species), and a nematode (Cosmocephalus species).

Mutualist Species:

• western gulls (Larus occidentalis)
• glaucous-winged gulls (Larus glaucescens)
• herring gulls (Larus argentatus)

Commensal/Parasitic Species:

• nematode (Cosmocephalus species)
• lice (Actornithophilus funebre)
• lice (Degeeriella praestans)
• lice (Menophon)
• lice (Philopterus melanocephalus)
• cestodes (Dibothriocephalus oblongatum)
• cestodes (Schistocephalus solidus)
• cestodes (Paricterotaenia species)
• trematodes (Diplostomum species)
• trematodes (Cotylurus species)
• trematodes (Ornithobilharzia species)
• trematodes (Clinostomum species)
• trematodes (Stephanoprora species)

Most predation is on eggs and hatchlings, which may be taken by a wide variety of avian, terrestrial, and aquatic predators. Reported predators on eggs and hatchlings include gull species (Larus), great horned owls (Bubo virginianus), common ravens (Corvus corvax), domestic cats (Felis catus), dogs (Canis lupus familiaris), coyotes (Canis latrans), red foxes (Vulpes vulpes), striped skunks (Mephitis mephitis), raccoons (Procyon lotor), northern pike (Esox lucius), and western diamondback rattlesnakes (Crotalus atrox). Adult Caspian terns may fall prey to avian predators, such as bald eagles (Haliaeetus leucocephalus) and terrestrial predators when roosting or on a nest (Canis latrans, Vulpes vulpes).

When a predator approaches a nesting colony, Caspian terns raise an alarm call and will often join together to mob the predator. They are aggressive and will chase any large bird that is close to a colony. Their diving attacks can be very effective, resulting in bloody wounds. However, their habit of taking flight to mob a predator may also leave eggs and nestlings vulnerable. Predators have been observed taking advantage of terns flying to grab eggs and nestlings from exposed nests. Chicks simply crouch in the nest scrape, and are cryptically colored, but will be detected by predators using scent or warmth to find prey.

Known Predators:

• gull species (Larus)
• great horned owls (Bubo virginianus)
• common ravens (Corvus corvax)
• domestic cats (Felis catus)
• dogs (Canis lupus familiaris)
• coyotes (Canis latrans)
• red foxes (Vulpes vulpes)
• striped skunks (Mephitis mephitis)
• raccoons (Procyon lotor)
• northern pike (Esox lucius)
• western diamondback rattlesnakes (Crotalus atrox)
• bald eagles (Haliaeetus leucocephalus)

Anti-predator Adaptations: cryptic

Nonbreeding: often rests with flocks of other terns. At a colony at the mouth of the Columbia River, 50% of adults foraged within 8 kilometers and 90% foraged within 21 kilometers (Collis et al. 1999); at other colonies, some adults travel long distances to obtain food; up to 50 kilometers on Lake Michigan (Cuthbert and Wires 1999) and 29-60 kilometers in another reported case (Gill 1976). At expanding colonies on the Pacific Coast, birds exhibited low natal philopatry (Collis et al. 1999), but elsewhere adults show strong fidelity to colonies (Cuthbert 1988).

Caspian terns, like most Sterna, use a variety of calls. Young begin to call from within the egg and use an "i-i-i" call to beg for food. Caspian terns use various calls to maintain contact, express alarm, advertise that they are bringing fish back to the nest, and to beg. Most calls are hoarse and sound like "ra" or "rau." During courtship, they make steep dives that produce a soft, buzzing sound with their wings. Caspian terns communicate through visual displays and body posturing as well.

Communication Channels: visual ; acoustic

Caspian terns, like most terns, use a variety of vocalizations. Young begin to call from within the egg and use an "i-i-i" call to beg for food. Caspian terns use various calls to maintain contact, express alarm, advertise that they are bringing fish back to the nest, and to beg. Most calls are hoarse and variations on a "ra" or "rau." During courtship, they make steep dives that produce a soft, buzzing sound with their wings.

Caspian terns communicate through visual displays and body posturing as well. Aggression is displayed with a "head up" posture, with the head held towards the other tern and the feathers ruffled. The head is then bowed forward, showing off the black cap. Appeasement is conveyed with the head held straight up and wings out.

Communication Channels: visual ; acoustic

As in most other animals, most deaths occur within a few months of hatching. Adults have high survival rates and can live more than 26 years in the wild.

As in most other animals, most mortality occurs within a few months of hatching (62% in some areas). Adults have high survival rates and can live more than 26 years in the wild.

Caspian terns form mated pairs that stay together for the breeding season. Some pairs remain together for many years, but only 25% of pairs mate again the next year in some populations. Pairs are formed soon after birds arrive on the breeding grounds, although some pairs form during migration or on the wintering range. Males attract mates with a "fish flight." Males capture a fish and then fly with it over a group of terns. Females and males join in the display, flying with the male as he repeatedly passes over the group. He then lands near a female and makes bowing movements with his head. Females may ignore the male, try to steal the fish, or beg for the fish. Pairs perform a "high flight" display together to cement the bond, ascending and diving together as they vocalize. Symbolic construction of nest scrapes is also part of the courtship ritual.

Mating System: monogamous

Caspian terns arrive on the breeding grounds from late March to late May. Pairs begin to form nest scrapes soon after they arrive on the breeding grounds. They breed in late May and early June, laying from 1 to 3 buffy, splotched eggs. Eggs are laid every 2 to 3 days in a simple depression scraped in the ground and incubation begins immediately with the first egg. Caspian terns have 1 brood yearly. Incubation is from 25 to 28 days and young begin to fly at 37 days after hatching. Most individuals don't breed until they are 3 years old.

Breeding interval: Caspian terns breed once yearly.

Breeding season: Caspian terns breed in late May or June.

Range eggs per season: 1 to 3.

Range time to hatching: 25 to 28 days.

Average fledging age: 37 days.

Range age at sexual or reproductive maturity (female): 2 (low) years.

Average age at sexual or reproductive maturity (female): 3 years.

Range age at sexual or reproductive maturity (male): 2 (low) years.

Average age at sexual or reproductive maturity (male): 3 years.

Both parents incubate the eggs. A parent will bring a fish and offer it to their mate on the nest, then take over incubating. Females tend to spend more time caring for eggs and young. Parents protect their young from heat by standing above them to provide shade. Young are semiprecocial when hatched, with downy feathers but relying on their parents for feeding. They remain in or near the nest for about a week after hatching. They are fed fish by parents soon after hatching and they begin to accompany parents on foraging trips within a week or so of learning to fly.

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

Caspian terns are monogamous, with pairs staying together at least for the breeding season. Some pairs remain together for many years, but only 25% of pairs mate again the next year in some populations. Pairs are formed soon after birds arrive on the breeding grounds, although some pairs form during migration or on the wintering range. Males attract mates with a "fish flight." Males capture a fish and then fly with it over a group of terns. Females and males join in the display, flying with the male as he repeatedly passes over the group. He then lands near a female and makes bowing movements with his head. Females may ignore the male, try to steal the fish, or beg for the fish. This display is usually repeated several times before the male will feed the fish to the female, at which point the bond is formed and they copulate. Pairs perform a "high flight" display together to cement the bond, ascending and diving together as they vocalize. Symbolic construction of nest scrapes is also part of the courtship ritual.

Mating System: monogamous

Caspian terns arrive on the breeding grounds from late March to late May. Pairs begin to form nest scrapes soon after they arrive on the breeding grounds. They breed in late May and early June, laying from 1 to 3 buffy, splotched eggs. Eggs are laid every 2 to 3 days in a simple scrape nest and incubation begins immediately with the first egg. Caspian terns have 1 brood yearly. Incubation is from 25 to 28 days and fledging occurs 37 days after hatching. Most individuals don't breed until they are 3 years old, although some attempt breeding in their 2nd year.

Breeding interval: Caspian terns breed once yearly.

Breeding season: Caspian terns breed in late May or June.

Range eggs per season: 1 to 3.

Range time to hatching: 25 to 28 days.

Average fledging age: 37 days.

Range age at sexual or reproductive maturity (female): 2 (low) years.

Average age at sexual or reproductive maturity (female): 3 years.

Range age at sexual or reproductive maturity (male): 2 (low) years.

Average age at sexual or reproductive maturity (male): 3 years.

Both parents incubate the eggs and alternate frequently throughout the day. A parent will relieve the other by bringing and offering a fish. Then the incubating parent takes the fish and moves off the nest. Females tend to spend more time caring for eggs and young. Parents protect their young from heat by standing above them to provide shade. Young hatch in the order they were laid and are semiprecocial when hatched, with downy feathers and reliant on the parents for feeding. They remain in or near the nest for about a week after hatching. They are fed fish by parents soon after hatching and they begin to accompany parents on foraging trips within a week or so of fledging. Caspian terns have the longest period of dependency of any tern species.

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

Along the U.S. mid-Atlantic coast, nesting begins by late May or early June. Clutch size usually is 2-3. Incubation, by both sexes, lasts 20-22 days. Young are tended by both parents, leave nest in a few days, first fly at 4-5 weeks. Parental care (feeding) may extend up to 5-7 months after fledging. Nests singly or usually in colonies of up to several thousand pairs (5000+ at Sand Island, Washington).

Caspian tern populations have declined in some parts of their range, especially in Europe and Africa where some populations have gone extinct. Populations in North America have increased because measures were taken to protect breeding areas and habitat. They are considered threatened in some states, including Michigan. They are considered "least concern" by the IUCN Red List because of their large geographic range and population sizes.

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: threatened

Resident breeder, regular passage visitor and winter visitor.

Caspian tern populations have declined in some parts of their range, especially in Europe and Africa where some populations have been extirpated. Populations in North America have largely increased because of measures taken to protect breeding areas and habitat. However, they are considered threatened in some states, including Michigan. They are considered "least concern" by the IUCN Red List because of their large geographic range and population sizes.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: threatened

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N4B - Apparently Secure

United States

Rounded National Status Rank: N4B,N4N : N4B: Apparently Secure - Breeding, N4N: Apparently Secure - Nonbreeding

Rounded Global Status Rank: G5 - Secure

Reasons: Large range, increasing numbers in some areas.

Comments: Disturbance and development of nesting habitat are major threats.

Management Requirements: Nesting sites can be augmented by providing artificially created ones (see GHABCOM).

Needs: Protection of nesting habitat is a major concern.

There are no known adverse effects of Caspian terns on humans.

Caspian tern eggs were once collected for food. They are colorful and fascinating members of native coastal faunas worldwide.

Positive Impacts: food

There are no known adverse effects of Caspian terns on humans.

Caspian tern eggs were once collected for food. They are colorful and fascinating members of native coastal faunas worldwide.

Positive Impacts: food

Comments: Formerly (AOU 1983, 1998) included in the genus Sterna but separated on the basis of genetic data that correspond to plumage patterns (Bridge et al. 2005).