West African Crested Tern

Adult West African Crested Terns are medium-sized birds with a body length of approximately 40 to 43 centimeters and a wingspan reaching up to 85 centimeters. They are easily identified by their black cap and distinctive crest, which contrasts sharply with their white underparts and pale grey upperparts. The bright orange bill is another distinguishing feature, contrasting with the dark head markings.

Juvenile terns exhibit more muted plumage, with less defined markings and a duller bill, which can lead to confusion with other tern species. However, as they mature, they develop the characteristic adult coloration. Males and females of this species are similar in appearance, though subtle differences may be seen in size, with females typically being slightly smaller.

In flight, the West African Crested Tern displays a graceful silhouette with long, pointed wings and a deeply forked tail. Their flight is buoyant and agile, often gliding over the water surface before diving to catch prey. When perched, they maintain an upright posture, often in groups along sandy beaches or rocky outcrops.

The diet of the West African Crested Tern primarily consists of small to medium-sized fish, which they catch through plunge-diving. They are adept hunters, often foraging in groups to efficiently exploit schools of fish. Their bright orange bill is perfectly adapted for grasping slippery prey from the water.

In addition to fish, these terns occasionally consume crustaceans and other small marine organisms, particularly when fish are less abundant. Seasonal variations in diet are observed, with a greater reliance on alternative prey during periods of low fish availability.

Foraging typically occurs during daylight hours, with peak activity in the early morning and late afternoon when fish are most active near the surface. The West African Crested Tern often follows fishing boats, taking advantage of disturbed fish populations, and may also feed in association with other seabirds.

West African Crested Terns are highly social birds, often seen in large, noisy flocks during the breeding season. They exhibit strong colonial nesting behavior, with hundreds of pairs nesting in close proximity on sandy or rocky islands. Their colonies are often mixed with other seabird species, such as gulls and other terns, which can offer some protection from predators.

During courtship, males perform elaborate displays, including aerial acrobatics and fish offerings to females. These behaviors help strengthen pair bonds and are crucial for successful mating. Once paired, both parents share responsibilities, including incubating eggs and feeding chicks.

Outside the breeding season, these terns remain gregarious, often joining mixed-species feeding flocks. They exhibit a range of vocalizations to communicate, especially when alarmed or during feeding activities. When threatened by predators, they rely on group mobbing strategies to deter potential threats.

West African Crested Terns build their nests in colonies on isolated beaches or rocky islands. The nests are simple scrapes in the sand or ground, often lined with bits of seaweed, shells, and other debris to provide some insulation for the eggs.

Clutch size typically consists of one to two eggs, which are pale with dark speckles, allowing them to blend into the sandy surroundings. Both parents share incubation duties, which last about 25 to 28 days. After hatching, the chicks are semi-precocial, meaning they are relatively mobile but still dependent on parents for feeding.

The fledging period lasts approximately five weeks, during which time the young birds develop their flight feathers and learn essential survival skills from their parents. West African Crested Terns usually raise one brood per year, although in areas with abundant food, a second brood may occasionally occur.

The primary call of the West African Crested Tern is a distinctive, harsh 'kreeee' or 'kyarr' sound, often repeated in quick succession. This call serves various functions, from maintaining contact within flocks to signaling alarm when predators approach.

During the breeding season, calls become more frequent and varied, with a mix of short chirps and longer, more complex vocalizations used in courtship displays. These sounds can often be heard at a distance, contributing to the cacophony typical of large tern colonies.

The West African Crested Tern does not have a dawn chorus per se, but its vocal activity peaks during the early morning hours when feeding and social interactions are most intense. Their calls, while not melodious, are a characteristic sound of the coastal environments they inhabit.

• 1The West African Crested Tern can be distinguished from the similar-looking Royal Tern by its slightly smaller size and brighter bill.
• 2Their nests are often situated so close together in colonies that adults have to carefully maneuver around neighboring nests.
• 3Unlike many seabirds, West African Crested Terns do not have a true migratory pattern but instead disperse along coastlines outside the breeding season.
• 4They can dive from heights of up to 10 meters to catch fish, a technique that requires precision and agility.
• 5During the breeding season, their black crest becomes more pronounced, serving as a visual cue in courtship displays.

The West African Crested Tern is currently listed as Near Threatened by the IUCN due to habitat loss and human disturbance. Coastal development, pollution, and overfishing pose significant threats to their populations. Conservation efforts focus on habitat protection, including the designation of marine protected areas and the enforcement of regulations to minimize human impact on breeding sites. Historical fluctuations in population sizes have highlighted the species' vulnerability to environmental changes. Recent studies suggest that while some populations remain stable, others are declining, emphasizing the need for continued monitoring and conservation action. International cooperation is crucial, given the species' wide range along the West African coast.