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8 Fascinating Facts About the Black Tern: Habitat Behavior and More

The Black Tern, also known as Chlidonias niger, is a small and graceful bird species belonging to the family Laridae. These birds are migratory and are found in freshwater habitats across

North America and


With their striking black plumage, the Black Terns are undoubtedly a birdwatchers delight. In this article, we will discuss the identification of these birds, their field identification, and other bird species similar to the Black Tern.

We will also look at their plumages, molts, and other interesting characteristics of these fascinating birds.


The Black Tern is a small, slender bird that measures between 25-30 cm in length and weighs approximately 40 g. They have a wingspan of 60-70cm and are distinguished by their dark black plumage that contrasts with their white underparts.

Unlike most birds, both male and female Black Terns appear similar, except during the breeding season when the males have a darker black cap and more vivid red beaks. Field


Black Terns are commonly found flying in flocks, often at low altitudes, over freshwater habitats such as lakes and lagoons.

One of the distinguishing features of the Black Tern is its characteristic buoyant, light, and fluttery flight style. They have a sharp and quick flight, alternating between brief flits and short glides as they hunt insects over the water surface.

They have a distinctive call, a rapid high-pitched “kit-ik-it-ik” or kirrik, which they use to communicate with members of their flock.

Similar Species

The most common bird species often confused with Black Terns is the Common Tern that shares a similar habitat, feeding ground, and breeding locations. However, Common Terns can be distinguished from Black Terns by their pale gray mantle, longer bill, and the white and black striped pattern on their heads during breeding season.

Other species that migrate with Black Terns, including Sooty Terns and Bridled Terns, have dark plumage but are significantly larger in size compared to the Black Tern.


Black Terns have two distinct plumages: the breeding and non-breeding plumage. During the breeding season, which occurs from May to September, they develop a striking black head and upperparts with contrasting gray wings.

The breeding Black Terns have a distinctive white triangle under their wings, with rich red-base bills, and bright red legs. In contrast, their non-breeding plumage is almost entirely gray with white ventral and underwing coverts.


Like many bird species, Black Terns go through a yearly molt. They undergo two molting events; the pre-breeding molt that occurs between June and July and the post-breeding molt between August and September.

During the pre-breeding molts, they replace their primaries, secondaries, and rectrices in an ordered sequence, whereas, during post-breeding, they replace the remaining feathers in any random order.


The Black Tern is a migratory bird that breeds in freshwater wetlands across

North America and

Eurasia. Their striking black plumage distinguishes them from other bird species while their light and fluttery-style flight is another noteworthy characteristic.

In conclusion, the Black Tern is an interesting bird species with unique features that make it a fascinating addition to the ecosystem. Their synchronized migration pattern and intricate molting process are among the many intriguing aspects of these avian creatures.

For birdwatching enthusiasts, spotting this species, especially during the breeding season, is a remarkable experience.

Systematics History

The Black Tern (Chlidonias niger) is a member of the family Laridae and is distributed across

North America and

Eurasia. The taxonomy of Black Terns has been the subject of debate, and several variations have been proposed.

Geographic Variation

Geographic variation in Black Terns is not well understood. However, studies have reported that there is no significant differentiation between the

North American and

Eurasian populations of Black Terns.

This suggests that the population similarities could be due to gene flow or the recent divergence of the two populations.


Three Black Tern subspecies have been proposed:

Chlidonias niger surinamensis,

Chlidonias niger niger, and

Chlidonias niger sunsauensis.

Chlidonias niger surinamensis

The surinamensis subspecies is found in the South American country of Suriname and is considered a non-breeding visitor.

Chlidonias niger niger

The niger subspecies inhabits regions throughout

Eurasia, ranging from Russia and Scandinavia to central Asia.

Chlidonias niger sunsauensis

The sunsauensis subspecies is found in Mongolia and northwestern China.

Related Species

Black Terns belong to the tribe Sternini along with other small and medium-sized gulls and terns. Species closely related to the Black Tern include the Common Tern (Sterna hirundo), the Roseate Tern (Sterna dougallii), the Arctic Tern (Sterna paradisaea), and the Little Tern (Sternula albifrons).

Historical Changes to Distribution

The Black Tern is distributed across

North America and

Eurasia, but its range varies from place to place. Black Terns are migratory birds and have been known to travel long distances during migration.

North America


North America, breeding populations are found from British Columbia to Nova Scotia, Great Plains to Gulf Coast. During the winter months, these birds can be found in Central and South America while some may travel to the coastal regions of the United States.



Eurasian population, on the other hand, breeds from the northern and eastern parts of Greenland to Russia and southern Scandinavia. During winter, these birds migrate to Africa and Southwest Asia.

It has been suggested that the Black Tern’s range has been impacted by climate change. Studies have indicated that breeding ranges have shifted northward in response to warmer climatic conditions.


The Black Tern’s taxonomy has been the subject of debate, and although there are three proposed subspecies, the geographic variation in the population has not been fully understood. Black Terns belong to the tribe Sternini, and closely related species include the Common Tern, the Roseate Tern, the Arctic Tern, and the Little Tern.

The Black Tern is a migratory bird, and their range varies depending on the breeding and non-breeding seasons. However, the impact of climate change on their range distribution continues to be a topic of discussion.


The Black Tern is a freshwater bird species and is found in a variety of wetland habitats, including shallow ponds, marshes, bogs, and lake shores. They are found across different altitudes, from coastlines to high altitudes of up to 2,500 meters.

However, they are not found in saline or brackish water habitats. The habitat of Black Terns also varies with their breeding and wintering locations.




North America, Black Terns breed in isolated, small wetlands that are surrounded by sphagnum moss or emergent vegetation. They are also found in natural or man-made ponds, shallow marshes and bogs, beaver ponds, or small lakes.


Eurasia, Black Terns breed in shallow freshwater habitats, including marshes and lagoons. Wintering


During the winter months, Black Terns can be found in tropical regions, including South America and Africa.

They are commonly found resting or feeding over freshwater bodies, including rivers, lagoons, and lakeshores.

Movements and Migration

Black Terns are migratory birds and undertake long-distance migrations from their breeding grounds to wintering locations. The migration of Black Terns is characterized by extensive movements from breeding locations to non-breeding wetland habitats.

Their migration is an adaptation to changing seasonal conditions, availability of food, and optimal breeding conditions.

Breeding Migration

Black Terns breeding in

North America have been known to travel to wintering locations, including Central and South America. On average, breeding populations in

North America migrate southward between August and September and return to their breeding grounds between late April and early May the following year.

Eurasian Black Terns breed in a variety of habitats between May and August. In September, they migrate to their wintering locations across the Mediterranean and Africa.

The migration of

Eurasian Black Terns is known to take place earlier than

North American Black Terns, between July and August. Non-

Breeding Migration

During the winter months, Black Terns have been observed in wetland habitats across Africa and South America. The migration of Black Terns during the non-breeding season is characterized by movements from breeding habitats to wintering habitats.

In South America, Black Terns are frequently found at the edges of large lakes, sometimes miles away from their breeding site.

Factors Affecting Movement and Migration

Black Terns respond to changes in seasonal conditions, resource availability, and breeding conditions, as well as to environmental changes and other disturbances. The survival of individual birds is strongly influenced by their ability to identify and select optimal breeding and wintering locations.

Biologically active areas provide abundant biotic resources, such as insects and freshwater fish, and Black Terns have been reported to visit specific locations for feeding and resting during their migration. Anthropogenic factors, including habitat modification, water pollution, and invasive species, have contributed to the decline of Black Tern populations and affected the timing and routes of their migration.

Evidence has suggested that, as a result of changing climate conditions, Black Tern populations may shift northward, which could impact their migration routes in the years to come.


Black Terns are freshwater birds and are found in a range of wetland habitats, where they breed, rest, and feed. During the breeding season,

North American Black Terns can be found in small wetlands surrounded by emergent vegetation, while

Eurasian Black Terns breed in shallow water habitats, including marshes and lagoons.

Black Terns undertake long-distance migrations between breeding habitats and wintering locations, responding to changing environmental conditions and resource availability. The timing of their migrations is influenced by breeding and non-breeding periods, and the factors considered when selecting optimal locations for feeding and resting.

Although their movements are well documented, the impact of anthropogenic factors, including human activities and changes in the climate, pose a significant threat to Black Tern populations in the years to come.

Diet and Foraging

Black Terns are primarily insectivorous birds, feeding on a wide variety of aquatic and terrestrial insects. They are visually oriented hunters and forage aerially, picking insects from the waters surface or catching them in the air.

Black Terns are also known to eat small fish, crustaceans, and mollusks, but only when insects are scarce.


Black Terns feed primarily in wetland habitats, especially small ponds, marshes, and swamps. They feed by hovering or flying over the water and using their sharp eyesight to locate prey.

Once they spot their prey, they either skim the surface of the water or hover above the water and pick the insects from the surface.


The diet of Black Terns primarily consists of aquatic and terrestrial insects, including dragonflies, mayflies, beetles, and moths. Their diet varies depending on the availability of insects, which changes seasonally.

Black Terns are opportunistic feeders, and their diet also includes small fish, crustaceans, and mollusks, but only when their preferred insect prey is scarce.

Metabolism and Temperature Regulation

Black Terns are endothermic and have a high metabolic rate, allowing them to maintain a high body temperature even when exposed to cold temperatures. They are also able to regulate their body temperature through a variety of mechanisms, including panting, open-mouthed gular breathing, and fenestrated, or porous, bill adaptation.

Sounds and Vocal


Black Terns have a variety of calls that they use for communication, including alarm calls, contact calls, and begging calls. Their vocalizations are important in maintaining group cohesion and signaling potential danger.


The calls of Black Terns are relatively simple, consisting of two or three notes emitted in a relatively rapid and repetitive manner. The most common call is a high-pitched, nasal “kit-ik-it-ik,” which they use to communicate with members of their flock or during courtship displays.

During the breeding season, males hold their wings in a particular manner and give a distinct courtship call, a series of mewing “kik-kik-kik-kik”s with a rising inflection. Black Terns also use their vocalizations when displaying territorial behavior or warding off intruders.

They emit a harsh “ker” call, accompanied by a forward-leaning posture and a fluffed-up body. This call functions as an alarm call, alerting other birds to potential danger.


Black Terns are primarily insectivorous birds, feeding on aquatic and terrestrial insects in wetland habitats. They use their sharp eyesight to locate prey and capture them by either skimming the water’s surface or hovering above the water.

Black Terns have a high metabolic rate and can regulate their body temperature through various mechanisms. They also have a variety of calls that they use for communication, including contact calls, alarm calls, courtship calls, and territorial calls.

The ability to communicate effectively through their vocalizations and adapt to the changing environment helps to ensure the survival and success of the Black Terns.


Black Terns have a range of behaviors that are significant in their survival, including their locomotion, self-maintenance, agonistic behavior, and sexual behavior.


Black Terns are graceful and agile flyers, capable of quick and sudden turns in the air. They have a buoyant, light, and fluttery flight style and use a combination of brief flits and short glides as they hunt for insects over water surfaces.

When taking off, they may run on the surface of the water with rapid steps before becoming airborne.

Self Maintenance

Black Terns spend a significant amount of time preening and cleaning their feathers. They use their beaks to remove debris and any parasites from their feathers, which helps to maintain their feathers insulating and aerodynamic properties.



Black Terns exhibit agonistic behavior towards other birds, particularly during the breeding season when competition for mating opportunities is typically higher. They use their wings, bills, and calls to ward off competitors and defend their territories.



During courtship displays, male Black Terns perform elaborate aerial displays, including circling flights and the presentation of food to females while hovering in the air. Males also exhibit a distinctive threat display, including erect posturing, lunging, and vocalizations, to ward off other males.


Breeding among Black Terns typically occurs in May to August in

North America and June to August in

Eurasia. They form monogamous pairs, with both males and females contributing to the creation of the nest and the care of the offspring.


Black Terns construct nests floating on the surface of the water, often using floating plant material and mud. The nests are concealed within vegetation or clumped together in colonies.

The female lays 2-3 eggs, which are incubated for approximately 21-24 days.

Parental Care

Both male and female Black Terns participate in the care of the chicks. The chicks are fed by regurgitation, which is initially fed a diet high in insects before gradually switching to fish and crustaceans.

The chicks fledge the nest within 16-22 days, but the parents continue to feed them for several weeks after they leave the nest.

Demography and Populations

Black Terns populations have experienced varied population trends across their range. In many regions of

North America, populations declined as a result of habitat loss and degradation, competition, predation, and human disturbance.

In contrast, populations in Europe have remained relatively stable. Conservation efforts have been implemented across different regions to mitigate the threats affecting Black Tern populations.


North America, various conservation strategies have been employed, including wetland restoration, the creation of artificial nesting sites, and population monitoring. Population modeling studies have predicted that climate change could have a significant impact on Black Tern populations in years to come.

Climate change could alter habitat availability, breeding success, and food supply, potentially leading to the decline of Black Tern populations across different regions.


The behavior of Black Terns is essential to their survival, with behaviors such as locomotion, self-maintenance, agonistic behavior, and sexual behavior playing critical roles.

Breeding among Black Terns occurs in floating nests, with both males and females contributing to their creation and care.

Black Tern populations have faced varied population trends depending on their range, with conservation efforts employed across different regions. Climate change poses a significant challenge to Black Tern populations, indicating that additional conservation strategies will be necessary to conserve them.

Maintaining the wetland habitats in which Black Terns depend on remains essential to ensuring the survival and success of the species.

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