The Pitt shag (Phalacrocorax featherstoni), also known as the Pitt Island shag or Featherstone's shag, is a species of bird in the family Phalacrocoracidae. It is endemic to Pitt Island where its natural habitats are open seas
and rocky shores. The bird with the color of a dark body, gray chest,
yellow eyes and feet can be found in small groups in their breeding
habitat or alone within 18 km from their territory searching for food.
The species was close to extinction in 1905 but actions of conservation
have been done ever since. The Pitt shag is threatened by habitat loss
due to predation and climate change causing a decline from 1997 to
2012, but there is a recovery plan by the Department of Conservation.
Members of the shag family belong to three groups, based on the color
of their feet: black, yellow or pink. Outside New Zealand, the
black-footed shags are better known as cormorants. The Pitt shag belongs
to the yellow footed group. They are about 63 cm in length and weigh
650–1300 g, with a slim build. The Pitt shag has a yellow colored detail
around the eyes, light gray at the neck and chest, and the rest of the
head, back, wings and tail with shades of black and navy.[2]
From the Spotted shag (Phalacrocorax punctatus), the Pitt shag became a subspecies.[2]
This representative of the shags in the Chatham Group was discovered by
H.H. Travers in 1871. Buller dedicated the species to Dr Featherston,
superintendent of the Province of Wellington at that time.[3] The Spotted shag and the Pitt shag have been determined as a part of the Phalacrocorax genus considering a DNA study.[4]
When apart from the group the Pitt shag is quiet, but during
mating season males make noises of grunting, gargling and ticking while
females remain silent.[2]
Shags find food on their own, traveling up to 18 km from their territory to feed on mostly small fish and when possible snails, worms and crustaceans found flying over waters and shores.[5]
From August to December, 2 to 3 year old Pitt shags gather in
small crowds on the rocky shores and cliffs of the coast, protecting
themselves against predators and weather. With up to 40 pairs of birds, nests
are created out of small branches, plants and seaweed, and are
eventually found with about 2 to 4 pale bluish-white colored eggs.
Parents take turns incubating the eggs for about 30 days, once hatched a
single parent will stay with the chicks for two weeks, then both
parents will search and feed their chicks until they fledge at around 6 to 8 weeks.[4]
Apparently never a common species, it was reported as nearly extinct in 1905. The Department of Conservation does have a recovery plan for this bird.
The Pitt shag is claimed endangered[6]
due to its loss of breeding habitat and rapidly declining, small
population. Studies show a record of 729 pairs found from 1997 to 1998,
547 pairs from 2003 to 2004, and 434 pairs from 2011 to 2012.[5] With nests planted along coastal cliffs predators are not much of a concern, although Feral Cats, Black Rats, Brown Rats, Common Brushtail Possum and Weka are known to be possible threats. The threat of human activity is more evident as it causes climate change, leading to changes in their environment and resources. These activities include introduction of predators, bycatch in the fishing industry, bird hunting, and crayfish pots.[5]
Conservation actions done specifically for the Pitt shag are not
very apparent, although other works on the Chatham Islands have been
done such as withdrawing sheep and cattle from the South East and
Mangere Islands in 1961 and 1968, and fencing coastal habitats to avoid
possible interference. Actions that are being considered are measuring
the whole adult population with intervals of 10 years starting from the
year a plan is created, and in each year study the pattern of two
communities. Other plans include analyzing the effect of rock lobster
fishing, additional fencing, continuous studying of the breeding and
foraging of the bird, and withdrawing feral cats, Wekas, sheep, cattle
and pigs concerning Pitt and Chatham Islands.[5]
The little pied cormorant, little shag or kawaupaka (Microcarbo melanoleucos) is a common species of Australasianwaterbird, found around the coasts, islands, estuaries, and inland waters of Australia, New Guinea, New Zealand, Timor-Leste and Indonesia, and around the islands of the south-western Pacific and the subantarctic.
It is a small short-billed cormorant usually black above and white
below with a yellow bill and small crest, although a mostly black
white-throated form predominates in New Zealand. Three subspecies are
recognised. Until recently, most authorities referred to this species as
Phalacrocorax melanoleucos.
In New South Wales
The species is known as the little pied cormorant in Australia, and as the little shag or by the Māori name of kawaupaka in New Zealand. The term white-throated shag is also reserved for the melanistic form there.[2]
In India
The little pied cormorant was originally described by French naturalist Louis Pierre Vieillot in 1817. In 1931, American ornithologist James Lee Peters was the first to consider this in a separate genus along with the pygmy cormorant (M. pygmaeus), little cormorant (M. niger), and the long-tailed cormorant (M. africanus).
Since then, molecular work by Sibley and Ahlquist showed the little
pied and long-tailed cormorants formed a group which had diverged early
on from other cormorants. This group of "micro-cormorants" assumed the
genus name Microcarbo, initially described by French naturalist Charles Lucien Bonaparte in 1855.[3] The generic name is derived from the Ancient Greek mikros "small", and Latincarbo "black". However, most older authorities refer to this species as Phalacrocorax melanoleucus.
In the now-extinct Waray language spoken along the Adelaide River in North Arnhem Land, the species was known as mawa.[4]
Wing drying pose
The little pied cormorant is a small cormorant measuring 56–58 cm
(22–23 in) with a shorter 3 cm (1.2 in) bill and longer tail than the little black cormorant; it has a small black crest. It is found in two morphs in New Zealand. Subspecies melanoleucos and brevicauda are found only in a pied morph, black (with a slight green tinge) above and white beneath. This is also found in subspecies brevirostris,
but in this form the melanistic morph is much more common. In this form
the entire plumage is black with a greenish tinge except for the sides
of the head, chin, throat and upper neck; the bill is yellow with black
on top. Intermediate forms are also found.[2]
The pied form is glossy black above with white face, underparts
and thighs. The bill and bare skin around the face are yellow. In both
forms the legs and feet are black.[5] The pied form is rare in New Zealand, and is most common there in Northland, where it makes up one in every four birds or so.[2]
Chicks have dark brown down, with pied morph having patches of
paler down. Immature birds are a dull blackish brown, with pied morph
birds having paler underparts.[2]
The little pied cormorant makes a low cooing during courtship.[2]
The species ranges across New Zealand, from Stewart Island to Northland,[2]
and across mainland Australia (although not in the arid interior of the
west of the country) and Tasmania. It is also present in Papua New Guinea, Palau, Timor-Leste, the Solomon Islands, New Caledonia, and Vanuatu. In eastern Indonesia, the little pied cormorant's range includes Sulawesi, the Lesser Sunda Islands, Maluku Islands, and Western New Guinea, with non-breeding birds recorded in Java, Bali, and once off the coast of East Kalimantan.[5] Widespread and common, it lives near bodies of water such as swamps, lakes, lagoons, estuaries and the coastline.[2][5]
The little pied cormorant is a benthic
feeder, i.e. it finds its prey on the sea floor. It is a solitary
feeder, normally diving in relatively shallow water, often near the
shore. Dive times are short, around 15 to 20 seconds, with recovery
times on the surface of 5 to 10 seconds unless prey are being swallowed.
It takes a variety of fish prey but an unusually high proportion
(nearly 30% by weight on average, and up to 80% in some individuals) of crustaceans. In New Zealand waters it is most often seen preying on the local flounder and other small flatfish.
Eels and insect larvae are also consumed. These are brought to the
surface to be swallowed: the bird will sometimes put a fish down on the
surface of the water in order to re-orient it and swallow it head first.
Because of this habit, they suffer some kleptoparasitism from red-billed gulls.
Breeding occurs once a year in spring or early summer in southern
areas of its range (southern Australia and New Zealand), and after the
monsoon in tropical regions.[7] The nest is a platform built of branches and sticks, often still green with leaves in the forks of trees, usually eucalypts
that are standing in water. Nests are often located near other
waterbirds such as other cormorants, herons, ibises or spoonbills. Four
or five pale blue oval eggs measuring 46 x 31 mm are laid. The eggs are covered with a thin layer of lime,
giving them a matte white coated appearance. They become increasingly
stained with faeces, as does the nest, over the duration of the breeding
season.[8]
The double-crested cormorant (Nannopterum auritum) is a member of the cormorant family of water birds. It is found near rivers and lakes and in coastal areas and is widely distributed across North America, from the Aleutian Islands in Alaska down to Florida and Mexico.
Measuring 70–90 cm (28–35 in) in length, it is entirely black except
for a bare patch of orange-yellow facial skin and some extra plumage
that it exhibits in the breeding season when it grows a double crest in
which black feathers are mingled with white. Five subspecies are
recognized. It mainly eats fish
and hunts by swimming and diving. Its feathers, like all cormorants,
are not waterproof, and it must dry them out after spending time in the
water. Once threatened by the use of DDT, the numbers of this bird have increased markedly in recent years.
The double-crested cormorant was described by René Primevère Lesson in 1831. It was formerly classified in the genus Phalacrocorax, but a 2014 study supported reclassifying it and several other American cormorant species into the genus Nannopterum.[3] The IOC followed this classification in 2021.[4]
Its scientific genus name is derived from the Greek words νᾶνος : nános, "small" and πτερόν : pterón, "wing". This genus name was originally coined for the flightless cormorant (N. harrisi), which does have very small wings; although the double-crested cormorant has normal-sized wings, it (along with the neotropic cormorant, N. brasilianum) was still reclassified into the genus Nannopterum when the relationship between it and the flightless cormorant became apparent. The species name is from the Latinauritus, "eared", referring to its nuptial crests.[5] Its common name refers to the same nuptial crests.
Close-up of an adult in breeding plumage with dark crests
The double-crested cormorant is a large waterbird with a stocky body,
long neck, medium-sized tail, webbed feet, and a medium-sized hooked
bill. It has a body length of between 70 and 90 cm (28 and 35 in) long,
with a wingspan of between 114 and 123 cm (45 and 48 in).
This species has dark-colored plumage with bare supra-loreal skin and gular skin that is yellow or orange. An adult in breeding plumage will be mostly black with the back and coverts
being a dark grayish towards the center. Nuptial crests, for which the
species is named, are either white, black or a mix of the two. These are
located just above the eyes with the bare skin on the face of a
breeding adult being orange. A non-breeding adult will lack the crests
and have more yellowish skin around the face. The bill of the adult is
dark-colored.[8] The double-crested cormorant is very similar in appearance to the larger great cormorant, which has a more restricted distribution in North America, mainly on the Canadian maritime provinces; it can, however, be separated by having more yellow on the throat and the bill.[10] The neotropic cormorant also looks very similar, and the two species can sometimes be found together where their ranges meet.
The plumage of juvenile double-crested cormorants is more dark
gray or brownish. The underparts of a juvenile are lighter than the back
with a pale throat and breast that darkens towards the belly. As a bird
ages, its plumage will grow darker. The bill of a juvenile will be
mostly orange or yellowish.[8]
A very common and widespread species, it winters anywhere that is ice-free along both coasts, as far north as southern Alaska (on the west coast) and southern New England (on the east coast). It can be found as far south as Mexico and the Bahamas. It migrates from the coldest parts of its breeding range, such as eastern Canada, and has occurred in Europe as a very rare vagrant, for example in Great Britain, Ireland, and the Azores.
The double-crested cormorant swims low in the water, often with just
its neck and head visible, and dives from the surface. It uses its feet
for propulsion and is able to dive to a depth of 1.5–7.5 m (4 ft 11 in –
24 ft 7 in) for 30–70 seconds. After diving, it spends long periods
standing with its wings outstretched to allow them to dry, since they
are not fully waterproofed. This species flies low over the water, with
its bill tilted slightly upward, sometimes leaving the colony in long,
single-file lines.
Food can be found in the sea, freshwater lakes, and rivers. Like all
cormorants, the double-crested dives to find its prey. It mainly eats fish, but will sometimes also eat amphibians, crustaceans and insects.[7]
Fish are caught by diving under water. Smaller fish may be eaten while
the bird is still beneath the surface but bigger prey is often brought
to the surface before it is eaten. Double-crested cormorants are also
considered pests to aquaculturists
because of their intense predation on fish ponds which can cause
thousands of dollars in losses to farmers.
Cormorants regurgitate pellets containing undigested parts of their
meals such as bones. These pellets can be dissected by biologists in
order to discover what the birds ate.
Parent and a chick at the nest
Breeding occurs in coastal areas as well as near inland rivers and
lakes. They build stick nests in trees, on cliff edges, or on the ground
on suitable islands. They are gregarious birds usually found in
colonies, often with other aquatic birds, and have a deep, guttural
grunt call.
The double-crested cormorant's numbers decreased in the 1960s due to the effects of DDT. Colonies have also been persecuted from time to time in areas where they are thought to compete with human fishing.
Recently the population of double-crested cormorants has
increased. Some studies have concluded that the recovery was allowed by
the decrease of contaminants, particularly the discontinued use of DDT.[12]
The population may have also increased because of aquaculture ponds in
its southern wintering grounds. The ponds favor good over-winter
survival and growth.
Adult in breeding plumage with white crests
In 1894, Thomas McIlwraith in his book, Birds of Ontario,
concludes his section on double-crested cormorants by saying: "When the
young are sufficiently grown, they gather into immense flocks in
unfrequented sections, and remain until the ice-lid has closed over
their food supply, when they go away, not to return till the cover is
lifted up in the spring."
For populations nesting in the Great Lakes region, it is believed that the colonization of the lakes by the non-native alewife (a small prey fish)
has provided optimal feeding conditions and hence good breeding
success. Double-crested cormorants eat other species of fish besides
alewives and have been suspected of contributing to the decline of some sport-fish populations in the Great Lakes and other areas.[13]
In light of this belief, and because of calls for action by the public, the United States Fish and Wildlife Service
(the U.S. federal government agency charged with their protection) has
recently extended control options to some other government entities.
This includes culling of populations and egg addling
to thwart reproduction, in an effort to control their growing numbers.
The U.S. Fish and Wildlife Service retains oversight and the control
measures are not extended to the general public (no hunting season).[14]
In May 2008, the Canadian government reduced significantly the number of nests of the birds on Middle Island, a small island in Lake Erie and part of Point Pelee National Park.[15] This is an attempt to keep the small island in balance and preserve its vegetation[16] but opponents to the plan have argued that it is based on faulty information, provided in part by anglers who view cormorants as competitors.[17] As of 2021, the cormorant culling program continues.[18]
In 2020 the government of Ontario introduced a hunting season for
double-crested cormorants from September 15 to December 31, allowing
any hunter to kill up to fifteen birds per day.[19]
Geographical distribution of Double-crested cormorant.
The Arctic tern (Sterna paradisaea) is a tern in the familyLaridae. This bird has a circumpolar breeding distribution covering the Arctic and sub-Arctic regions of Europe (as far south as Brittany), Asia, and North America (as far south as Massachusetts). The species is strongly migratory, seeing two summers each year as it migrates along a convoluted route from its northern breeding grounds to the Antarctic
coast for the southern summer and back again about six months later.
Recent studies have shown average annual round-trip lengths of about
70,900 km (38,300 nmi) for birds nesting in Iceland and Greenland, and about 48,700 km (26,300 nmi) for birds nesting in the Netherlands, while an individual from the Farne Islands in Northumberland with a light level geolocator
tag covered a staggering 96,000 km (52,000 nmi) in ten months from the
end of one breeding season to the start of the next. These are by far
the longest migrations known in the animal kingdom.
Flatey Island, Western Iceland
Arctic terns are medium-sized birds. They have a length of 28–39 cm (11–15 in) and a wingspan of 65–77 cm (26–30 in),[3][4] and weigh around 100 g.[5]
In the breeding season they are mainly grey and white plumaged, with a
blood red beak and feet, a black crown and nape, and white cheeks. The
mantle is grey, and the scapulars grey, tipped white. The upper wing is
grey with a white leading edge and a narrow blackish trailing edge on
the primary feathers; the collar is completely white, as is the rump.
The deeply forked tail is whitish, with grey outer webs. In winter, the
forehead becomes partly white, and the bill and legs are black.[3] Juveniles also have a partly white forehead, and narrow pale orangey-brown fringes on the grey mantle feathers (unlike common tern, where the mantle feathers are more completely gingery-brown).[3]
Arctic terns are long-lived birds, with many reaching fifteen to thirty years of age, with a record of 31 years.[5] They eat mainly fish and small marine invertebrates.
The species is abundant, with an estimated two million individuals.
While the trend in the number of individuals in the species as a whole
is not known, exploitation in the past has reduced this bird's numbers
in the southern reaches of its ranges.
The genus name Sterna is derived from Old English "stearn", "tern".[6] The specific paradisaea is from Late Latinparadisus, "paradise".[7]
The Scots names pictarnie,[8]tarrock[9] and their many variants are also believed to be onomatopoeic, derived from the distinctive call.[10] Due to the difficulty in distinguishing the two species, all the informal common names are shared with the common tern.[11]
An Arctic tern nesting on the Farne Islands, from where the longest migration is recorded
The Arctic tern has a continuous worldwide circumpolar breeding distribution; there are no accepted subspecies. It can be found in coastal regions in cooler temperate parts of North America and Eurasia during the northern summer. During the southern summer, it can be found at sea, reaching the northern edge of the Antarctic ice.[12]
The Arctic tern is famous for its migration; it flies from its
Arctic breeding grounds to the Antarctic and back again each year. The
shortest distance between these areas is 19,000 km (12,000 mi). The long
journey ensures that this bird sees two summers per year and more
daylight than any other creature on the planet.[13] One example of this bird's remarkable long-distance flying abilities involves an Arctic tern ringed as an unfledged chick on the Farne Islands, Northumberland, UK, in the northern summer of 1982 that reached Melbourne, Australia in October, just three months after fledging, a journey of more than 22,000 km (14,000 mi).[14] Another example is that of a chick ringed in Labrador, Canada, on 23 July 1928. It was found in South Africa four months later.[15]
A 2010 study using tracking devices attached to the birds showed
that the above examples are not unusual for the species. In fact, the
study showed that previous research had seriously underestimated the
annual distances travelled by the Arctic tern. Eleven birds that bred in
Greenland or Iceland covered 70,900 km (38,300 nmi) on average in a
year, with a maximum of 81,600 km (44,100 nmi).[16]
The difference from previous estimates is due to the birds taking
meandering courses rather than following a straight route as was
previously assumed. The birds follow a somewhat convoluted course in
order to take advantage of prevailing winds.[17]
The average Arctic tern lives about 30 years and will, based on the
above research, travel some 2.4 million km (1.5 million mi) during its
lifetime, the equivalent of a roundtrip from Earth to the Moon more than
three times.[18]
A 2013 tracking study of half a dozen Arctic terns breeding in the Netherlands[19]
shows average annual migrations of c. 48,700 km (26,300 nmi). On their
way south, these birds roughly followed the coastlines of Europe and Africa.[20]
In a 2015–2017 study of Arctic terns on the Farne Islands in Northumberland, an individual with a light level geolocator
tag 'G82' covered a staggering 96,000 km (52,000 nmi) in just 10 months
from the end of one breeding season to the start of the next, setting a
new global migration record by travelling not just the length of the
Atlantic Ocean and the width of the Indian Ocean, but also half way
across the South Pacific to the boundary between the Ross and Amundsen Seas, before returning back west along the Antarctic coast and back up the Atlantic.[21][22][23]
Arctic terns usually migrate sufficiently far offshore that they are rarely seen from land outside the breeding season.[24]
The Arctic tern is a medium-sized bird around 33–36 cm (13–14 in)
from the tip of its beak to the tip of its tail. The wingspan is
76–85 cm (30–33 in).[24] The weight is 86–127 g (3.0–4.5 oz). The beak is dark red, as are the short legs and webbed feet. Like most terns, the Arctic tern has high aspect ratio wings and a tail with a deep fork.[24]
The adult plumage
is grey above, with a black nape and crown and white cheeks. The
upperwings are pale grey, with the area near the wingtip being
translucent. The tail is white, and the underparts pale grey. Both sexes
are similar in appearance. The winter plumage is similar, but the crown
is whiter and the bills are darker.[24]
Juveniles differ from adults in their black bill and legs,
"scaly" appearing wings, and mantle with dark feather tips, dark carpal
wing bar, and short tail streamers.[24] During their first summer, juveniles also have a whiter forecrown.[25]
The species has a variety of calls; the two most common being the alarm call, made when possible predators (such as humans or other mammals) enter the colonies, and the advertising call.[26]
While the Arctic tern is similar to the common and roseate terns,
its colouring, profile, and call are slightly different. Compared to
the common tern, it has a longer tail and mono-coloured bill, while the
main differences from the roseate are its slightly darker colour and
longer wings. The Arctic tern's call is more nasal and rasping than that
of the common, and is easily distinguishable from that of the roseate.[27]
This bird's closest relatives are a group of South Polar species, the South American (Sterna hirundinacea), Kerguelen (S. virgata), and Antarctic (S. vittata) terns.[28]
The immature plumages of Arctic tern were originally described as separate species, Sterna portlandica and Sterna pikei.[29]
with an eel
Breeding begins around the third or fourth year.[30] Arctic terns mate for life and, in most cases, return to the same colony each year.[31]Courtship is elaborate, especially in birds nesting for the first time.[32]
Courtship begins with a so-called "high flight", where a female will
chase the male to a high altitude and then slowly descend. This display
is followed by "fish flights", where the male will offer fish to the
female. Courtship on the ground involves strutting with a raised tail
and lowered wings. After this, both birds will usually fly and circle
each other.[32]
Both sexes agree on a site for a nest, and both will defend the
site. During this time, the male continues to feed the female. Mating
occurs shortly after this.[32] Breeding takes place in colonies on coasts, islands and occasionally inland on tundra near water. It often forms mixed flocks with the common tern. It lays from one to three eggs per clutch, most often two.[24]
It is one of the most aggressive terns, fiercely defensive of its
nest and young. It will attack humans and large predators, usually
striking the top or back of the head. Although it is too small to cause
serious injury to an animal of a human's size, it is still capable of
drawing blood, and is capable of repelling many raptorial birds, polar
bears[33] and smaller mammalian predators such as foxes and cats.[13]
The nest is usually a depression in the ground, which may or may
not be lined with bits of grass or similar materials. The eggs are
mottled and camouflaged.[24] Both sexes share incubation duties. The young hatch after 22–27 days and fledge after 21–24 days.[24] If the parents are disturbed and flush from the nest frequently the incubation period could be extended to as long as 34 days.[26]
When hatched, the chicks are downy. Being precocial, the chicks begin to move around and explore their surroundings within one to three days after hatching.[34] Usually they do not stray far from the nest. Chicks are brooded by the adults for the first ten days after hatching.[35] Both parents care for hatchlings.[24] Chick diets always include fish, and parents selectively bring larger prey items to chicks than they eat themselves.[26] Males bring more food than females. Feeding by the parents lasts for roughly a month before being weaned off slowly.[24] After fledging, the juveniles learn to feed themselves, including the difficult method of plunge-diving.[36] They will fly south to winter with the help of their parents.[37]
Arctic terns are long-lived birds that spend considerable time raising only a few young, and are thus said to be K-selected.[38] A 1957 study in the Farne Islands estimated an annual survival rate of 82%.[39]
adult with juvenile
The diet of the Arctic tern varies depending on location and time, but is usually carnivorous. In most cases, it eats small fish or marine crustaceans.[12][24] Fish species comprise the most important part of the diet, and account for more of the biomass consumed than any other food. Prey species are immature (1–2-year-old) shoaling species such as herring, cod, sandlances, and capelin.[13] Among the marine crustaceans eaten are amphipods, crabs and krill. Sometimes, these birds also eat molluscs, marine worms, or berries, and on their northern breeding grounds, insects.[34]
juvenile
Arctic terns sometimes dip down to the surface of the water to
catch prey close to the surface. They may also chase insects in the air
when breeding.[34] It is also thought that Arctic terns may, in spite of their small size, occasionally engage in kleptoparasitism by swooping at birds so as to startle them into releasing their catches.[34] Several species are targeted—conspecifics, other terns (like the common tern), and some auk and grebe species.[26]
While nesting, Arctic terns are vulnerable to predation by cats and other animals.[12] Besides being a competitor for nesting sites, the larger herring gull steals eggs and hatchlings. Camouflaged eggs help prevent this, as do isolated nesting sites.[36]
Scientists have experimented with bamboo canes erected around tern
nests. Although they found fewer predation attempts in the caned areas
than in the control areas, canes did not reduce the probability of
predation success per attempt.[40] While feeding, skuas, gulls, and other tern species will often harass the birds and steal their food.[41]
The total population for the arctic tern is estimated at more than
two million individuals, with more than half of the population in
Europe. The breeding range is very large, and although the population is
considered to be decreasing, this species is evaluated as a species of least concern by the IUCN.[1] Arctic terns are among the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds applies.[42]
The population in New England was reduced in the late nineteenth-century because of hunting for the millinery trade.[26] Exploitation continues in western Greenland, where the population of the species has been reduced greatly since 1950.[43] In Iceland, the Arctic tern has been regionally uplisted to Vulnerable as of 2018, due to the crash of sandeel (Ammodytes spp.) stocks.[44]
At the southern part of their range, the Arctic tern has been reducing in numbers. Much of this is due to a lack of food.[25] However, most of these birds' range is extremely remote, with no apparent trend in the species as a whole.[34] The Arctic terns' dispersal pattern is affected by changing climatic conditions,[45]
and its ability to feed in its Antarctic wintering is dependent on
sea-ice cover, but unlike breeding species, it is able to move to a
different area if necessary, and can be used as a control to investigate
the effect of climate change on breeding species.[46]
Wing drying pose
Close-up of an adult in breeding plumage with dark crests
Displaying,
Parent and a chick at the nest
adult with juvenile
juvenile
