La Sterne Caspienne dans le Lac Saint-Pierre

The caspian tern

The Caspian Tern (Hydroprogne caspia)

The Caspian tern is the largest of the terns, recognizable by its imposing size and elegant flight. It frequents various coastal and lake environments, where its ability to travel great distances makes it an efficient migrant and an indicator of the health of aquatic ecosystems.

Sexual dimorphism

Males and Females: Sexual dimorphism is low in the Caspian Tern.
Both sexes have similar plumage, although slight variations in color may be observed during the breeding season.

Size and wingspan

Size: The Caspian Tern is about 45 to 50 cm long.
Wingspan: Its wingspan varies from 90 to 105 cm, giving it excellent long-distance gliding capabilities.
Weight: Generally, it weighs between 200 and 300 grams.

Beak and legs

Beak: Its thin, pointed, slightly curved beak is perfectly adapted for grasping small aquatic prey, such as fish and invertebrates.
Legs: The legs are relatively long and lightly webbed, allowing good mobility on sandy or rocky surfaces as well as in shallow water.

Social behavior

The Caspian Tern is often seen in groups during migration periods and at roosting sites, although it is generally solitary when hunting.
During the breeding season, it forms colonies on secure nesting sites, which promotes collective protection against predators.

Voice

Its vocalizations, consisting of whistles and piercing calls, facilitate communication between individuals, particularly during reproductive interactions.

Breeding Habitat

Coastal Areas and Islands: The Caspian Tern frequently nests on isolated islands or cliffs along the coast, where security and an abundance of prey ensure breeding success.
Lake and Reservoir Shores: It can also breed on sites located near large inland bodies of water with sandy beaches or rocky banks.

migration habitat

Temporary Coastal Sites: During migrations, it uses various sites along the coasts, such as beaches and estuaries, for feeding and resting.
Inland Wetlands: Inland bodies of water also provide convenient stopovers for feeding during its long journeys.

wintering habitat

Areas with Unfrozen Waters: In winter, the Caspian Tern migrates to areas where water bodies remain free of ice, ensuring continuous access to food resources.
Coastal Areas: Estuaries and coastal areas rich in prey support its feeding during the cold season.

habitat features

Sandy or Rocky Soil: Nesting sites often have sandy or rocky soils that provide good protection from predators.
Presence of Clear Water: The clarity of the waters encourages a high density of fish and invertebrates, essential for its diet.
Open Spaces: Large open spaces allow the Caspian Tern to make long gliding flights to locate prey.

Adaptation to the Habitat

Its large wingspan and gliding ability allow it to travel great distances in search of food.
The thin, pointed beak is an optimal adaptation for efficiently capturing small prey in varied environments.
Its lightly webbed feet provide good mobility over diverse terrain, facilitating the transition between resting and feeding sites.
Colony formation during nesting contributes to collective defense, improving the survival of young against predators.

Les oiseaux du lac st-pierre

Les
hérons