The Atlantic Cod (Gadus morhua) is a medium to large saltwater fish: generally averaging two to three kilograms in weight and about 65 to 100 centimetres in length, the largest cod on record weighed about 100 kg and was more than 180 cm long! Individuals living closer to shore tend to be smaller than their offshore relatives, but male and female cod are not different in size, wherever they live.

The Atlantic Cod shares some of its physical features with the two other species of its genus, or group of species, named Gadus. The Pacific Cod and Alaska Pollock also have three rounded dorsal fins and two anal fins. They also have small pelvic fins right under their gills, and barbels (or whiskers) on their chins. Both Pacific and Atlantic Cod have a white line on each side of their bodies from the gills to their tails, or pectoral fins. This line is actually a sensory organ that helps fish detect vibrations in the water.

The colour of an Atlantic Cod is often darker on its top than on its belly, which is silver, white or cream-coloured. Its exact colour varies between individuals and seems to depend on its habitat in order to camouflage, or blend in: when there’s lots of algae around, a cod can be reddish to greenish in colour, while a paler grey colour is more common closer to the sandy bottom of the ocean. In rocky areas, a cod may be a darker brown colour. Cod are often mottled, or have a lot of darker blotches or spots.

The Atlantic Cod may live as long as 25 years.

The North Atlantic Right Whale (Eubalæna glacialis) is one of the rarest of the large whales. It can weigh up to 63,500 kilograms and measure up to 16 metres. That’s the length of a transport truck and twice the weight! Females tend to be a bit larger than males – measuring, on average, one metre longer. Considering its weight, it’s fairly short, giving it a stocky, rotund appearance. Its head makes up about a fourth of its body length, and its mouth is characterized by its arched, or highly curved, jaw.  The Right Whale’s head is partially covered in what is called callosities (black or grey raised patches of roughened skin) on its upper and lower jaws, and around its eyes and blowhole. These callosities can appear white or cream as small cyamid crustaceans, called “whale lice”, attach themselves to them. Its skin is otherwise smooth and black, but some individuals have white patches on their bellies and chin. Under the whale’s skin, a blubber layer of sometimes more than 30 centimetres thick helps it to stay warm in the cold water and store energy. It has large, triangular flippers, or pectoral fins. Its tail, also called flukes or caudal fins, is broad (six m wide from tip to tip!), smooth and black. That’s almost the same size as the Blue Whale’s tail, even though Right Whales are just over half their size. Unlike most other large whales, it has no dorsal fin.

For a variety of reasons, including its rarity, scientists know very little about this rather large animal. For example, there is little data on the longevity of Right Whales, but photo identification on living whales and the analysis of ear bones and eyes on dead individuals can be used to estimate age. It is believed that they live at least 70 years, maybe even over 100 years, since closely related species can live as long.

Unique characteristics

The Right Whale has a bit of an unusual name. It is thought to have been named by whalers as the “right” whale to hunt due to its convenient tendencies to swim close to shore and float when dead. Its name in French is more straightforward; baleine noire, the black whale.

The American Eel (Anguilla rostrata) is a fascinating migratory fish with a very complex life cycle. Like salmon, it lives both in freshwater and saltwater. But its life-cycle is exactly the reverse of salmon’s: the eel is a catadromous species. It is born in saltwater and migrating to freshwater to grow and mature before returning to saltwater to spawn and die. The American Eel can live as long as 50 years.

It is a long, slender fish that can grow longer than one metre in length and 7.5 kilograms in weight. Males tend to be smaller than females, reaching a size of about 0.4 m. With its small pectoral fins right behind its gills, absence of pelvic fins, long dorsal and ventral fins and the thin coat of mucus on its tiny scales, the adult eel slightly resembles a slimy snake but are in fact true fish. Adult eels vary in coloration, from olive green and brown to greenish-yellow, with a light gray or white belly. Females are lighter in colour than males.  Large females turn dark grey or silver when they mature.

It is known by a variety of names in Canada, including: the Atlantic Eel, the Common Eel, the Silver Eel, the Yellow Eel, the Bronze Eel and Easgann in Irish Gaelic. In Indigenous languages, like Mi’kmaq, it is known as k’at or g’at, the Algonquins call it pimzi or pimizi, in Ojibwe bimizi, in Cree Kinebikoinkosew and the Seneca call it goda:noh.

The American Eel is the only representative of its genus (or group of related species) in North America, but it does have a close relative which shares the same spawning area: the European Eel. Both have similar lifecycles but different distributions in freshwater systems except in Iceland, where both (and hybrids of both species) can be found.

Barn Swallow (photo by J.J. Cadiz)

The Barn Swallow (Hirundo rustica) is a medium-sized songbird, about the size of a sparrow. It measures between 15 and 18 centimeters (cm) in length and 29 to 32 cm in wingspan, and weighs between 15 and 20 grams (g). But while it is average-sized, it’s far from average-looking! Its back and tail plumage is a distinctive steely, iridescent blue, with light brown or rust belly and a chestnut-coloured throat and forehead. Their long forked tail and pointed wings also make them easily recognizable. It’s these wings, tail and streamlined bodies that make their fast, acrobatic flight possible. Both sexes may look similar, but females are typically not as brightly coloured and have shorter tails than males. When perched, this swallow looks almost conical because of its flat, short head, very short neck and its long body.

Although the average lifespan of a Barn Swallow is about four years, a North American individual older than eight years and a European individual older than 16 years have been observed.

Sights and sounds:
Like all swallows, the Barn Swallow is diurnal –it is active during the day, from dusk to dawn. It is an agile flyer that creates very acrobatic patterns in flight. It can fly from very close to the ground or water to more than 30 m heights. The species may be the fastest swallow, as it’s been recorded at speeds close to 75 kilometers per hour (km/h). When not in flight, the Barn Swallow can be observed perched on fences, wires, TV antennas or dead branches.

Both male and female Barn Swallows sing both individually and in groups in a wide variety of twitters, warbles, whirrs and chirps. They give a loud call when threatened, to which other swallows will react, leaving their nests to defend the area.

Stinkpot

Freshwater turtles are reptiles, like snakes, crocodilians and lizards. Like other reptiles, they are ectothermic, or “cold-blooded”, meaning that their internal temperature matches that of their surroundings. They also have a scaly skin, enabling them, as opposed to most amphibians, to live outside of water. Also like many reptile species, turtles lay eggs (they are oviparous). But what makes them different to other reptiles is that turtles have a shell. This shell, composed of a carapace in the back and a plastron on the belly, is made of bony plates. These bones are covered by horny scutes made of keratin (like human fingernails) or leathery skin, depending on the species. All Canadian freshwater turtles can retreat in their shells and hide their entire body except the Common Snapping Turtle (Chelydra serpentina). This shell is considered perhaps the most efficient form of armour in the animal kingdom, as adult turtles are very likely to survive from one year to the next. Indeed, turtles have an impressively long life for such small animals. For example, the Blanding’s Turtle (Emydoidea blandingi) can live for more than 70 years! Most other species can live for more than 20 years.

There are about 320 species of turtles throughout the world, inhabiting a great variety of terrestrial, freshwater and marine ecosystems on every continent except Antarctica and its waters. In Canada, eight native species of freshwater turtles (and four species of marine turtles) can be observed. Another species, the Pacific Pond Turtle (Clemmys marmorata), is now Extirpated, having disappeared from its Canadian range.  Also, the Eastern Box Turtle (Terrapene carolina) has either such a small population that it is nearly Extirpated, or the few individuals found in Canada are actually pets released in the wild. More research is needed to know if these turtles are still native individuals. Finally, the Red-eared Slider (Trachemys scripta elegans), has been introduced to Canada as released pets and, thus, is not a native species.

Little Brown Bat

The Little Brown Bat, or Little Brown Myotis (Myotis lucifugus) weighs between 7 and 9 g, and has a wingspan of between 25 and 27 cm.  Females tend to be slightly larger than males but are otherwise identical. As its name implies, it is pale tan to reddish or dark brown with a slightly paler belly, and ears and wings that are dark brown to black.

Contrary to popular belief, Little Brown Bats, like all other bats, are not blind. Still, since they are nocturnal and must navigate in the darkness, they are one of the few terrestrial mammals that use echolocation to gather information on their surroundings and where prey are situated.  The echolocation calls they make, similar to clicking noises, bounce off objects and this echo is processed by the bat to get the information they need. These noises are at a very high frequency, and so cannot be heard by humans.

Narwhals (Monodon monoceros) are considered medium-sized odontocetes, or toothed whales (the largest being the sperm whale, and the smallest, the harbour porpoise), being of a similar size to the beluga, its close relative. Males can grow up to 6.2 m -the average size being 4.7 m- and weigh about 1,600 kg. Females tend to be smaller, with an average size of 4 m and a maximum size of 5.1 m and weigh around 900 kg. A newborn calf is about 1.6 m long and weighs about 80 kilograms. The narwhal has a deep layer of fat, or blubber, about 10 cm thick, which forms about one-third of the animal’s weight and acts as insulation in the cold Arctic waters.

Like belugas, they have a small head, a stocky body and short, round flippers. Narwhals lack a dorsal fin on their backs, but they do have a dorsal ridge about 5 cm high that covers about half their backs. This ridge can be used by researchers to differentiate one narwhal from another. It is thought that the absence of dorsal fin actually helps the narwhal navigate among sea ice. Unlike other cetaceans –the order which comprises all whales–, narwhals have convex tail flukes, or tail fins.

These whales have a mottled black and white, grey or brownish back, but the rest of the body (mainly its underside) is white. Newborn narwhal calves are pale grey to light brownish, developing the adult darker colouring at about 4 years old.  As they grow older, they will progressively become paler again. The narwhal’s colouring gives researchers an idea about how old an individual is. Some may live up to 100 years, but most probably live to be 60 years of age.

The narwhal’s most striking feature is undoubtedly its tusk. This long, spiral upper incisor tooth (one of the two teeth narwhals have) grows out from the animal’s upper jaw, and can measure up to 3 m and weigh up to 10 kg. Although the second, smaller incisor tooth often remains embedded in the skull, it rarely but on occasion develops into a second tusk. Tusks typically grow only on males, but a few females have also been observed with short tusks. The function of the tusk remains a mystery, but several hypotheses have been proposed. Many experts believe that it is a secondary sexual character, similar to deer antlers. Thus, the length of the tusk may indicate social rank through dominance hierarchies and assist in competition for access to females. Indeed, there are indications that the tusks are used by male narwhals for fighting each other or perhaps other species, like the beluga or killer whale.  A high quantity of tubules and nerve endings in the pulp –the soft tissue inside teeth – of the tusk have at least one scientist thinking that it could be a highly sensitive sensory organ, able to detect subtle changes in temperature, salinity or pressure.  Narwhals have not been observed using their tusk to break sea ice, despite popular belief. Narwhals do occasionally break the tip of their tusk though which can never be repaired.  This is more often seen in old animals and gives more evidence that the tusk might be used for sexual competition.  The tusk grows all throughout a male’s lifespan but slows down with age.

The scientific name for the Ruffed Grouse is Bonasa umbellus. Both terms are from the Latin: Bonasa means good when roasted and umbellus, a sunshade. This refers to the ruff or dark-coloured neck feathers that are particularly large in the male. When he is in display before the female, these are erected and surround his head almost like an umbrella. By nodding his head and ruffs, and spreading his tail and strutting, the male identifies himself to the female and encourages her advances.

The male Ruffed Grouse is about the size of a bantam chicken and weighs about 500 g. The females are smaller. Unlike the chicken, the grouse has a broad flat tail that is usually held down but that may be erected and spread into a half circle.

The dappled and barred plumage ranges in colour from pale grey through sombre red to rich mahogany. In the east, most grouse are predominantly grey, although some are red. Greys are in the majority in the central parts of the continent, and on the west coast most grouse are reddish brown.

The colours worn by the grouse are related to their habitat: the dark-coloured grouse inhabit dark forest, as on the coast; grey grouse live in lighter bush. This camouflage helps protect the grouse from their predators.

Males are hard to tell from females at a distance, but they are larger with larger ruffs and a longer tail. In the male the broad band of dark colour in the tail is usually unbroken.

The Ruffed Grouse is frequently called the “partridge.” This leads to confusion with the Gray, or Hungarian, Partridge, which was introduced to Canada from Europe. The Ruffed Grouse is only distantly related to the Gray Partridge, which is a bird of open areas, not woodlands.

Ptarmigans are hardy members of the grouse family that spend most of their lives on the ground at or above the treeline. Three species are present in North America: the Willow Ptarmigan Lagopus lagopus, the White-tailed Ptarmigan Lagopus leucurus, and the Rock Ptarmigan Lagopus mutus.

Like other grouse, ptarmigans have chunky bodies, short tails and legs, and short, rounded wings. Willow Ptarmigans weigh from 450 to 800 g, White-tailed Ptarmigans weigh about 350 g, and Rock Ptarmigans are intermediate in size.

All ptarmigans have feathered feet, unique among chickenlike birds, which improve their ability to walk in snow. They also have white wings throughout the year. Inflatable red combs above their eyes, which are especially evident in territorial and courting males, are inconspicuous to barely visible in females.

Ptarmigans have three seasonal plumages per year, instead of the two that are usual for most birds. These plumages keep the birds, particularly the female, well camouflaged at all times. In winter, all ptarmigans of both sexes are basically white. Whereas White-tailed Ptarmigans have permanently white tail feathers, the tails of Willow and Rock Ptarmigans remain black throughout the year. In winter, male—and some female—Rock Ptarmigans sport a black stripe that extends through the eye to the bill (as if they had put on charcoal goggles to prevent snow blindness), distinguishing them from male Willow Ptarmigans.

In ptarmigans, the moult, or shedding of old feathers, starts with the head and progresses towards the tail. As soon as the spring snowmelt begins, females moult into a barred breeding plumage of brown, gold, and black. Female ptarmigans are difficult to tell apart in spring, but the overall tones of the White-tailed Ptarmigan females are cooler in comparison to those of the other two species. Breeding males delay their moult.

The Piping Plover Charadrius melodus is a small bird of lakeshores, river sandbars, and ocean coasts. With its head and back the colour of dried sand, the Piping Plover blends well into its beach surroundings, helping it hide from predators. It has a white rump, a partially black tail, a black band above its white forehead, and a single black “belt” or breastband (also referred to as a collar or neckband), which is sometimes incomplete, that contrasts with its white breast and abdomen. Its bright orange legs match its orange, black-tipped bill. Adults weigh from 43 to 64 g and are about the size of a bluebird.

Males and females are similar in appearance, although the males tend to have broader and more distinct black bands on the head and breast and a brighter orange bill. The adult winter plumage, which looks like the juvenile plumage, lacks the black head and breast bands. On the wintering grounds, orange legs distinguish the Piping Plover from other plover species.

The Piping Plover is the rarest of six “belted” plover species found in North America. The single band, or “belt,” of the Piping Plover tends to be more incomplete in coastal birds and complete in interior birds. The Piping Plover is often confused with the Semipalmated Plover Charadrius semipalmatus, which is similar in size to the Piping Plover but has a darker body, the colour of wet sand, lacks a white rump patch, and has more pronounced black bands on the forehead, cheek area, and neck. Taxonomically, the Piping Plover is split into two subspecies. The circumcinctus subspecies occurs in the Northern Great Plains and Great Lakes regions. The melodus subspecies is restricted to the Atlantic coast.

Signs and sounds

The Piping Plover’s call is a plaintive cry, sometimes described as a whistled peep-lo, with the first syllable higher. The male calls vigorously during its courtship flights and when preparing nest scrapes.

Shorebirds form one of the most interesting, important, and spectacular groups of birds in Canada. They comprise a diverse group of species, including the plovers, oystercatchers, avocets, stilts, turnstones, sandpipers, yellowlegs, snipes, godwits, curlews, and phalaropes.

To the uninitiated, many species of shorebirds, especially the smaller sandpipers, appear confusingly similar, representing variations on a design involving long legs, a long bill, sharp, dynamic wings, and a streamlined body. These design features all reflect the lifestyle for which the birds are adapted—long legs for wading in water or on mudflats or marshes, the long bill for searching for tiny animal and insect prey by probing into Arctic tundra or a variety of substrates, and long wings and a streamlined body for swift flight over long distances.

The Redhead Aythya americana is a well-known and widely distributed North American diving duck. The adult male is a large, grey-backed, white-breasted duck with a reddish-chestnut head and black neck and chest. It resembles the larger male Canvasback. At close range, the head appears puffy, with an abrupt forehead and a short, broad bill, while the Canvasback’s bill is longer and slopes down from the forehead. The adult female is a large, brown-backed, white-breasted duck with a brown head, whitish chin, abrupt forehead, short, broad bill, and pearl-grey wing patches. Female Redheads, although larger, may be confused with female Ring-necked Ducks and scaups.

In autumn young Redheads resemble adult females, although their breast plumage is dull grey-brown, rather than white. During November and December, the young begin to develop the adult plumage, which has almost completely grown in by February.

The genus Aythya, to which the Redhead belongs, includes 12 species, all of which are well adapted to diving. The body is rounded and thick with large feet, legs set back on the body, and a broad bill. Body shapes vary from the big, long-necked, long-billed Canvasback to the short-billed scaup. The genus is represented in North America by the Canvasback, Redhead, Greater Scaup, Lesser Scaup, and Ring-necked Duck.

Adult coho salmon have silvery sides and metallic blue backs with irregular black spots. Spawning males have bright red sides, and bright green backs and heads, with darker colouration on their bellies. The fish have hooked jaws and sharp teeth. Young coho salmon are aggressive, territorial and often vibrantly coloured, with a large orange anal fin edged in black and white.

Adult Trumpeter Swans Cygnus buccinator are large birds with white feathers and black legs and feet. The feathers of the head and the upper part of the neck often become stained orange as a result of feeding in areas rich in iron salts. The lack of colour anywhere on the swans’ bodies distinguishes them from other white species of waterfowl, such as snow geese, which have black wing tips.

The male swan, or cob, weighs an average of 12 kg. The female, or pen, is slightly smaller, averaging 10 kg. Wings may span 3 m. Young of the year, or cygnets, can be distinguished from adults by their grey plumage, their yellowish legs and feet, and until their second summer of life, their smaller size.

The shape and colour of the bill help in identifying the Trumpeter and Tundra swans in the field. Trumpeters have all black bills; Tundra Swans, formerly called Whistling Swans, have more sloping bills, usually with a small yellow patch in front of the eye. If this patch is missing, it is quite difficult to distinguish between the two birds unless the voice is heard. At close range, an observer should look for a salmon-red line on the lower bill.

A third type of swan, the Eurasian Mute Swan, is often seen in Canadian parks and zoos. The Mute is all white with a black knob on a reddish-orange and black bill. The Trumpeter Swan is the largest of the three species.

Signs and sounds

Although very similar in appearance, the Trumpeter Swan and the Tundra Swan have quite different voices. The Trumpeter Swan has a deep, resonant, brassy, trumpet-like voice; the voice of the Tundra Swan is softer and more melodious.

The Tundra Swan Cygnus columbianus, formerly known as the Whistling Swan, is a large bird with white plumage and black legs, feet, and beak. However, when it is feeding in iron-rich areas, the feathers on its head and neck may take on a reddish tinge.

The male weighs on average 7.5 kg and can measure 1.3 m from bill to tail. The adult female is about the same size as the male but weighs slightly less, about 6.3 kg. The young of the year are smaller than the adults and have grey plumage, pinkish beaks with black tips, and pink legs and feet. It takes at least two years for adult plumage to grow in.

There are seven species of swans in the world. Two of these, the Tundra Swan and the Trumpeter Swan C. buccinator, are native to North America; their respective populations comprise 140 000 and 16 000 individuals. One non-native species, the Mute Swan, is found in North America,. People brought Mute Swans from Europe and Asia for ornamental display in parks and zoos, and now this species is found in the wild in certain parts of the continent. The Tundra Swan is the most common of the three species of swan found in Canada.

Although Trumpeter Swans are slightly larger than Tundra Swans, it is very difficult to tell the two species apart. At close range, a small yellow mark at the base of the bill, close to the eye, can be seen on the Tundra Swan. There is no such mark on the Trumpeter Swan.

Signs and sounds

Although very similar in appearance, the Trumpeter Swan and the Tundra Swan have quite different voices. The Trumpeter Swan has a deep, resonant, brassy, trumpet-like voice; the voice of the Tundra Swan is softer and more melodious.

The Tundra Swan’s former name “whistling swan” referred to the sound made by the slow, powerful beating of the wings in flight, and not to the voice of the bird. The call is pitched lower than a whistle and more closely resembles a blowing or tearing sound.

When thousands of birds are concentrated at a migratory staging point, the level of sound is very high, particularly at night when much of the social activity takes place.

Common Tern

Everyone who has visited the coast is familiar with gulls, those graceful, long-winged birds that throng the beaches and harbours and boldly beg for scraps. The gulls are a family of birds that live mainly at sea, either along the shore, or out in the ocean itself. Worldwide, there are more than 350 species of birds that live either partially or exclusively at sea, and these are generally known as "seabirds.”

The table below lists the 14 families of marine birds and the approximate number of species in each (the exact number of species is continually being revised as genetic research reveals that some very similar-looking birds are so different in their genetic makeup that they constitute different species). All species belonging to the albatross, auk, frigatebird, gannet, penguin, petrel, and storm-petrel families feed exclusively at sea. In addition, many species of cormorants, grebes, gulls, jaegers, loons, pelicans and terns feed either entirely or mainly at sea. The Phalaropes are the only shorebirds that feed at sea.

Families of birds in which all species feed either entirely of partially at sea and the approximate number of species in each family appear below (from http://www.worldbirdnames.org/ioc-lists/master-list/). The number of species that breed in Canada are shown in parentheses. Ducks and grebes that feed at sea are not included.

Of the 19 species of raptors, or birds of prey, in Canada, three are Accipiters. Accipiters are small to medium-sized hawks of swift flight that occur around the world. The Canadian species are the Sharp-shinned Hawk Accipiter striatus, the Cooper’s Hawk Accipiter cooperii, and the Northern Goshawk Accipiter gentilis. The Sharp-shinned Hawk is found in North, Central, and South America, the Cooper’s Hawk only in North America, and the Northern Goshawk on five continents.

Accipiters can be distinguished from other types of hawks by their flight silhouettes (see sketch). Like the buteos (e.g., the Red-tailed Hawk Buteo jamaicensis) and harriers (the Northern Harrier Circus cyaneus is the only Canadian harrier), the accipitrine hawks have rounded wings; however, these are shorter than in the other two groups. In contrast, the wings of another group of hawks, the falcons, such as the Kestrel or Sparrow Hawk Falco sparverius, are pointed.

All accipiters generally have similar colouring, small heads, long tails, and short rounded wings. The female of each species grows larger than the male. They range in size from the small male Sharp-shinned Hawk, which is smaller than a gull, to the large female Northern Goshawk, which at 55 to 66 cm is larger than a crow. The Cooper’s Hawk is intermediate in size; the male Cooper’s is easily confused with the female Sharp-shinned Hawk, and the female Cooper’s Hawk is almost as large as the male Northern Goshawk. There are distinguishing characteristics—for example, the shape of the tail is square for the Sharp-shinned Hawk, rounded for the Cooper’s Hawk, and almost square for the Northern Goshawk—but identification is difficult.

Many naturalists and hunters consider the Wood Duck Aix sponsa to be the most beautiful duck in North America, if not the world. The male in its multi-coloured breeding plumage, worn from October through June, is unexcelled among ducks. The female is less showy, although still beautiful and more colourful than other female ducks.

Wood Ducks are intermediate in size, between the Mallard and Blue-winged Teal; on average, males weigh 680 g and females weigh 460 g. From a distance, the male Wood Duck on the water appears as a dark-bodied, dark-breasted, light-flanked duck with a striped crested head and a light-coloured throat. At close range, its iridescent plumage, red eyes, and black, red, and white bill are conspicuous. A white eye-ring, light-coloured throat, and fine crest distinguish the female from both the male Wood Duck and females of other species. Both sexes usually show a downward pointing crest at the back of the head, and their long broad square tails are distinctive features in flight.

The wings of Wood Ducks are highly characteristic. The primary wing feathers, which are the 10 outermost flight feathers attached to the wing beyond the wrist, are dark in colour. The outer vanes of these feathers look as if they have been sprayed with aluminum paint. The Wood Duck is the only North American duck so marked.

The Roseate Tern Sterna dougallii is a seabird that resembles a small gull, but it has the typically slender body, short legs, and long, pointed wings of all terns. It is closely related to the Common Tern Sterna hirundo and the Arctic Tern Sterna paradisaeaand is frequently found in their company. For these reasons, the Roseate Tern is not easy to identify (see drawings). It is a paler grey than Arctic and Common terns, and its tail streamers are considerably longer.

The adult Roseate Tern is 33 to 34 cm in length and has a wingspan of 72 to 80 cm. At a weight of approximately 100 to 120 g, an adult is slightly smaller than a Mourning Dove. It has a black forehead and nape, and its upper wing is a pale grey. Its tail is white with deeply forked outer feathers that give the impression of long streamers when the bird is in flight. The underside of the tern is white, tinged with pink early in the breeding season; however, this pale rosy tint is not a good field mark, or identification characteristic, because it varies from bird to bird, and the colour tends to be bleached out by the sun. The legs and feet are reddish, and the bill is mostly black, although bills of breeding birds may be red at the base. Male and female birds look alike. The head of the nonbreeding adult is mottled black and white.

The juvenile Roseate Tern has a mottled greyish back and rump and dark bill and legs. Chicks are unevenly covered with down, giving them a spiky appearance; their legs are dark purplish to black.

Signs and sounds

All terns have a harsh cry, but the Roseate Tern has a distinctive, two-syllable call — kir-rick. This is often the best way of confirming its presence at a colony.