Swift Tern vs Sandwich Tern
Belonging to the same genus, both birds, swift tern and sandwich tern, exhibit a range of common characteristics between them. However, the differences between these two terns would be interesting to know. External features with their colouration differences are important to notice in distinguishing swift terns from sandwich terns as discussed in this article.
Swift Tern
Swift tern, Thalasseus bergii, aka great crested tern (Family: Sternidae), lives around warmer coastlines and islands of tropical and subtropical regions of Indian and Pacific Oceans. There are five subspecies of swift terns, varied according to respective geographical range. Swift tern is a large and stocky tern with a body length of 48 centimetres and a body weight of almost 400 grams. It has a shaggy black crest and a long slightly down-curved yellow colour bill. Upper parts of their body is plain grey in adults but streaked with white colour feathers in juveniles and during non-breeding season. Ventral and undersides are white but little black towards the tips of the underwings. It has black and short legs, and both male and females look similar in plumage. They show colonial nesting on either sandy or rocky or coral islands at low altitudes. They are omnivores and sea fish are their main prey items.
Sandwich Tern
Sandwich tern, Thalasseus sandvicensis, is also a member of sternidae family. There are three subspecies of sandwich terns as geographical races. They inhabit coastlines around Atlantic Ocean mostly. However, they migrate to warmer coasts of South Asian, Persian, Mediterranean, and West African countries during winter. It is a medium sized sea bird with a length around 42 centimetres. Upper parts of their body has pale grey colour feathers and the under parts are white in colour. During breeding season, their hood is completely black, but the small crest is always black in colour. Their bill is black and slender with the tip is yellow. They breed in extensively dense colonies on grounds around freshwater lakes close to coast. During breeding season, males go fishing and bring presents for their females.
|
What is the difference between Swift Tern and Sandwich Tern? • Upper parts of both birds have grey feathers, but those are darker in swift tern than in sandwich terns. • Juveniles have grey upper feathers with white streaks in swift terns, while those are browner with darker streaks in sandwich terns. • Bill is yellow in swift tern and black with a yellow tip in sandwich tern. • During winter, the white forehead is prominent in adults of sandwich terns compared to swift terns. • Shaggy black crest is prominent in swift tern, and is less extensive in sandwich tern. • There are five geographical subspecies in swift tern, while there are only three of them in sandwich tern. • Swift terns migrate to coasts of Western Africa, South Asia, Persia, Mediterranean, and warmer Americas in winter. However, sandwich terns live around coasts of Indian and Pacific Oceans.
|