Black-bellied Tern Bird Facts (Sterna acuticauda)

The Black-bellied Tern is a medium-sized tern with distinctive colouration. In breeding plumage, it has a black cap and belly, contrasting with its pale grey upperparts, white throat, and darker grey wings. The bill is yellow-orange, and the legs are reddish-orange. The underwings show a striking white pattern with a darker band across the flight feathers.

Non-breeding adults have a white forehead (streaked with black), belly, and a black band behind the eye. The bill develops a black tip during this period. Juveniles can be distinguished by their reddish bill base and blackish feet, along with darker markings than similar species.

The Black-bellied Tern is not typically found in Woodland habitats.

The Black-bellied Tern is not typically found in Garden habitats.

The Black-bellied Tern can be found in Wetland habitats.

The Black-bellied Tern can be found in Coastal habitats.

The Black-bellied Tern is not typically found in Urban habitats.

The Black-bellied Tern is not typically found in Farmland habitats.

The Black-bellied Tern is not typically found in Grassland habitats.

The Black-bellied Tern is not typically found in Desert habitats.

The Black-bellied Tern is not typically found in Tundra habitats.

The Black-bellied Tern is not typically found in Rainforest habitats.

The Black-bellied Tern is not typically found in Mountain habitats.

The Black-bellied Tern is not typically found in Savanna habitats.

Black-bellied Terns inhabit large rivers, lakes, and coastal areas across South and Southeast Asia. They are found in countries such as India, Bangladesh, Myanmar, and Cambodia. These birds prefer freshwater habitats but may also frequent estuaries and coastal lagoons.

During the non-breeding season, some populations move to coastal areas or undertake short-distance migrations within their range following changing water levels and food availability.

This map gives you a rough idea of where you might spot a Black-bellied Tern. The coloured areas show countries where these birds have been seen.

A few things to keep in mind:

Birds might not be everywhere in the coloured areas, for example, they may be present around the coast of that country
Where birds live can change with seasons and available food
This map is quite simple - it doesn't show exact locations

We're working on making our maps even better! Soon, we hope to show you:

More detailed maps for bigger countries, including state and region
How birds move around during different seasons

Species that can be found in the area throughout the year

Bangladesh India Myanmar Nepal Pakistan

Species that appear infrequently (rare) and unpredictably outside their normal range

Cambodia China Laos Thailand Vietnam

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Bird Attributes Explained

Our bird attributes system rates various aspects of a bird's capabilities on a scale of 0-100, based on data from field observations, scientific studies, and expert knowledge.

Attribute Categories:

Agility: Manoeuvrability, speed, and grace in flight or movement.
Strength: Physical power, often correlating with size and hunting abilities.
Adaptability: Ability to thrive in various environments or changing conditions.
Aggressiveness: Territorial behaviour and assertiveness, particularly during breeding seasons.
Endurance: Stamina, often seen in migration patterns or foraging behaviours.

Understanding the Ratings:

0-20: Very Low
21-40: Low
41-60: Average
61-80: High
81-100: Very High

Remember, these attributes are relative to other bird species and don't necessarily indicate superiority.

Agility

Reflects the bird's manoeuvrability, speed, and grace in flight or movement.

The Black-bellied Tern demonstrates remarkable agility through its precise plunge-diving technique, low-altitude flight patterns, and ability to hover effectively whilst hunting. Their forked tail provides excellent manoeuvrability, particularly when making quick directional changes during fishing.

Strength

Indicates the bird's physical power, often correlating with size and hunting abilities.

Whilst capable of carrying fish prey and maintaining steady flight in varying conditions, the Black-bellied Tern's relatively modest size (90-150g) and slender build suggest moderate strength. Their ability to plunge-dive effectively requires some muscle power, but they're not notably strong compared to other waterbirds.

Adaptability

Represents the bird's ability to thrive in various environments or changing conditions.

These terns show good adaptability through their ability to utilise both freshwater and coastal habitats, adjust to seasonal changes, and modify their hunting techniques (including following fishing boats). They can nest on various substrates, including floating vegetation, demonstrating flexible behaviour.

Aggressiveness

Measures the bird's territorial behaviour and assertiveness, particularly during breeding seasons.

During breeding season, Black-bellied Terns display territorial behaviour and will actively defend their nesting sites. They're known to produce harsh alarm calls when threatened and will mob potential predators, though they're not among the more aggressive tern species.

Endurance

Reflects the bird's stamina, often seen in migration patterns or foraging behaviours.

Their capacity for sustained low-altitude hunting flights, ability to migrate short distances, and regular plunge-diving activities demonstrate good endurance. They can maintain speeds of up to 40 km/h while hunting and spend considerable time airborne searching for prey, indicating strong stamina.

Black-bellied Terns primarily feed on small fish, which they catch by plunge-diving into water. They also consume aquatic insects, crustaceans, and occasionally small amphibians.

These terns often follow fishing boats to catch discarded fish or those stirred up by nets.

Black-bellied Terns are often seen flying low over water, scanning for prey. They hover briefly before plunge-diving to catch fish.

These terns are generally social, forming small flocks during non-breeding seasons and often associating with other tern species at roosting sites.

The Black-bellied Tern's call is a harsh, grating 'kree-ah' or 'kik-kik'. During the breeding season, they become more vocal, producing a series of rapid, high-pitched notes that sound like 'ki-ki-ki-ki'. When alarmed, they emit a sharp, piercing 'keeya' call.

Breeding occurs primarily during the dry season when river levels are low. Black-bellied Terns form monogamous pairs and nest in small colonies, often with other tern species. They select sandy or rocky islands in rivers or lakes for nesting.

Nests are simple scrapes in the ground, sometimes lined with small pebbles. The female typically lays 2-3 eggs, which are pale buff with dark brown spots. Both parents share incubation duties.

Incubation lasts about 21-22 days, and chicks fledge after 25-30 days. Parents continue to care for the young for several weeks after fledging.

The Black-bellied Tern is classified as Endangered due to rapid population decline. Major threats include habitat loss, water pollution, and disturbance of nesting sites.

Conservation efforts focus on protecting riverine habitats and raising awareness among local communities about the importance of these birds.

Look for Black-bellied Terns near large rivers, lakes, and coastal areas
Observe their distinctive low flight and hovering behaviour over water
Listen for their harsh, grating calls during breeding season
Watch for their unique plunge-diving feeding technique

Main predators include large birds of prey, such as eagles and falcons, as well as corvids, gulls, and some mammals that may raid nests.

Black-bellied Terns are excellent swimmers, despite rarely being seen on water.
They have been known to nest on floating vegetation in some areas.
These terns can fly at speeds of up to 40 km/h when hunting.

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