Sandwich Tern vs. Swift Tern

Attribute	Sandwich Tern	Swift Tern
Scientific Name	Sterna sandvicensis	Sterna bergii
Family	Laridae	Laridae
Size	Medium-sized	Medium-sized
Wingspan	100-110 cm	85-95 cm
Weight	350-450 grams	250-350 grams
Habitat	Coastal areas, estuaries	Coastal areas, estuaries
Diet	Fish, crustaceans	Fish, crustaceans
Migration	Migratory	Migratory
Breeding Range	Europe, Asia, Africa	Africa, Asia, Australia
Conservation Status	Least Concern	Least Concern

Introduction

The Sandwich Tern and Swift Tern are two species of seabirds that belong to the tern family. While they share some similarities, they also have distinct attributes that set them apart. In this article, we will explore the physical characteristics, habitat, behavior, diet, and conservation status of both species, providing a comprehensive comparison of these fascinating birds.

Physical Characteristics

The Sandwich Tern (Thalasseus sandvicensis) is a medium-sized seabird with a length of about 37-43 cm (14.5-17 inches) and a wingspan of approximately 85-97 cm (33.5-38 inches). It has a black cap on its head, a long black bill with a yellow tip, and a white body with gray wings. In contrast, the Swift Tern (Thalasseus bergii) is slightly larger, measuring around 45-50 cm (17.7-19.7 inches) in length and having a wingspan of about 100-115 cm (39.4-45.3 inches). It also has a black cap, but its bill is entirely black, and its body is a darker gray overall.

Both species have long, pointed wings that enable them to soar and dive with agility. They also possess webbed feet, which aid in swimming and diving for prey. These physical adaptations make them well-suited for their marine habitats.

Habitat

The Sandwich Tern is primarily found in coastal areas of the Atlantic and Mediterranean, breeding in colonies on sandy beaches, dunes, or islands. It prefers habitats with shallow waters and nearby estuaries or lagoons, where it can find an abundant supply of fish. During the non-breeding season, it migrates to warmer regions, including West Africa and the Caribbean.

The Swift Tern, on the other hand, has a more extensive range, inhabiting coastal regions of the Indian and Atlantic Oceans. It breeds on islands, coastal cliffs, or sandy beaches, often in mixed colonies with other seabirds. It can be found in South Africa, Namibia, Australia, New Zealand, and various islands in the Indian Ocean. During the non-breeding season, it may disperse widely, reaching as far as the Arabian Peninsula and the coasts of India and Sri Lanka.

Behavior

Both tern species are highly social and form large colonies during the breeding season. They are known for their aerial acrobatics, gracefully swooping and diving to catch fish near the water's surface. They are also skilled at plunge-diving, where they fold their wings and dive headfirst into the water to capture prey. This behavior is facilitated by their sharp eyesight, allowing them to spot fish from above.

While the Sandwich Tern is generally more gregarious, the Swift Tern tends to be more aggressive and territorial, especially during the breeding season. It will defend its nesting site vigorously, often engaging in aerial battles with intruders. The Sandwich Tern, on the other hand, is more tolerant of neighboring nests and may even form mixed colonies with other tern species.

Diet

Both tern species primarily feed on fish, but they may also consume crustaceans and other small marine creatures. The Sandwich Tern typically hunts for fish in shallow coastal waters, using its keen eyesight to locate prey from above. Once it spots a fish, it will hover briefly before diving headfirst to catch it. It can also be seen plunge-diving from the air or diving from a perched position on a rock or buoy.

The Swift Tern, on the other hand, is known for its ability to catch fish on the wing. It often feeds in large flocks, flying low over the water's surface and snatching fish with its sharp bill. This behavior is facilitated by its longer wings and more streamlined body, allowing it to maneuver swiftly and efficiently while in flight.

Conservation Status

The conservation status of both tern species varies, with the Sandwich Tern being classified as "Least Concern" by the International Union for Conservation of Nature (IUCN). Although it faces threats such as habitat loss, disturbance at breeding sites, and predation, its large population and wide distribution contribute to its overall stability.

The Swift Tern, on the other hand, is listed as "Near Threatened" by the IUCN. It has a more restricted range and is susceptible to various threats, including habitat degradation, disturbance, and predation. Conservation efforts are underway to protect its breeding sites and ensure the long-term survival of this species.

Conclusion

In conclusion, the Sandwich Tern and Swift Tern are two remarkable seabird species that share similarities in their physical characteristics, habitat preferences, and feeding habits. However, they also exhibit distinct attributes in terms of size, bill coloration, behavior, and conservation status. Understanding these differences allows us to appreciate the unique qualities of each species and highlights the importance of conservation efforts to protect their populations and habitats.