Arctic Tern Fact Sheet
By Rayne Billings
The Arctic tern is a small coastal waterbird that has a dark forehead, a sharp beak, long pointed wings, and bright red legs and feet. They can be found in Alaska during the summer when they come to breed. They are often seen in coastal areas, where they will dive into the water to catch small fish. Arctic terns have one of the longest migrations of any animal, which range from the Arctic to the Antarctic — a distance of, at minimum, 25,000 miles round-trip.
Although they are not currently endangered, they are at risk of losing large portions of their range due to global climate change and warming. It is believed that their range will continue shifting further north to combat this.
DID YOU KNOW…
Although terns are waterbirds, they have very small webbed feet, meaning that they do not swim well. They are usually only in the water for as long as it takes to grab a bite of food.
Arctic terns are thought to have the longest migration of any animal on Earth. Their migration can be at least 25,000 miles per year, stretching from their breeding grounds in the Arctic down to Antarctica.
In 2016, one Arctic tern was recorded traveling 59,650 miles during their migration.
Terns belong in the same taxonomic family as gulls.
Terns are one of the few birds that can hover in midair.
Photo courtesy of University of British Columbia/Mark Mallory
SCIENTIFIC AND COMMON NAMES
Sterna paradisaea, Arctic Tern, Kichyát (Tlingit)
GENERAL DESCRIPTION
Terns are a group of small, slender waterbirds that have gray wings and red webbed feet. There are three total species of terns in Alaska: the Arctic tern, the Aleutian tern, and the Caspian tern. Arctic terns are the most commonly seen throughout the state, with the other two species being rather rare.
Arctic terns are smaller than gulls and thinly-built with long, forked tails. Their beaks are sharp and pointed. Terns will often fly with their beaks pointed at a right angle towards the ground. On top of their forehead is a black patch of feathers that will be larger in size during the breeding season. Arctic terns’ bills, feet, and legs are bright red. They have high-pitched, raspy calls. Arctic terns are about a foot long and have a 30 inch wingspan.
RANGE
Map courtesy of The Audubon Society
The Arctic tern has the largest breeding range of any Alaskan waterbird. They nest throughout the state, from Utqiagvik down to Ketchikan. They will occasionally nest inland, despite being a waterbird. Some Arctic terns will even nest as far south as Washington State or New England. They will only be in North America for the summer breeding season. During the winter, they live on pack ice in Antarctica.
Arctic terns can be seen in a variety of places besides Alaska, such as South America, Western Europe, Iceland, Australia, New Zealand, and on Pacific Islands.
THREATS/CONCERNS
Globally, Arctic tern populations appear to be stable. However, they can be difficult to observe because their range is so remote. Their long life span of up to 34 years could also mask population declines.
One of the largest potential threats facing the Arctic tern is climate change in the Arctic and Antarctic. Under potential global temperature increases, it is estimated that the Arctic tern’s range could be decreased by 48%. It is projected that their range will continue shifting further north to combat overall warming temperatures.
Another threat to the Arctic tern is predation and disturbances, which the eggs and hatchlings are very sensitive to. In 2019, a wolf ate seven nest’s worth of eggs at Mendenhall Glacier in Juneau, Alaska. It is also believed that, during the same time period, a domestic dog ate several eggs as well. Because of this, along with a few other predation events, no new fledglings were born in Juneau that year, which was of concern as the local population of Arctic terns appears to be declining. Loose dogs can cause harm to tern populations through both eating the eggs and causing stress to the breeding adults.
LIFE HISTORY
Terns usually arrive at their summer breeding grounds in May and will begin nesting soon after. They build their nests near freshwater or saltwater on sandpits, beaches, and islands. When nesting inland, they build their nests on tundra or near ponds. Arctic terns mate for life and will often form large breeding colonies.
They will usually lay two eggs, which are brown with light spots. The eggs hatch in about 23 days. The hatchlings will leave the nest soon after and hide in surrounding bushes, where they are fed small fish by the parents. After about 25 days, the hatchlings will be able to fly. They will stay with their parents for another month.
Typically, Arctic terns only spend about three months in their breeding grounds before leaving for their southward migration towards Antarctica. While terns are usually very noisy birds, just before migration begins they will stay silent in a behavior known as “dread.” It is unknown as to why this happens. After dread is over, the colony will begin migration all at once. Most of the migration takes place over offshore waters and will usually last a few months.
Arctic terns migrate in order to stay where it is summer. While it is winter in the Northern Hemisphere, it is summer in the Southern Hemisphere. Sunlight in the summer allows them to easily find the small fish that they eat. It is possible that the Arctic tern experiences more daylight than any other animal on the planet due to their migration patterns.
Arctic terns are so lightweight that they are able to utilize ocean breezes to carry them long distances without flapping their wings. They are able to sleep and eat while gliding. It is commonly assumed that the terns utilize “unihemispheric sleep,” or the practice of sleeping with one half of the brain at a time. However, it is also possible that they do not sleep or sleep for very short periods of time during migration. If Arctic terns did not need to stop and eat, they would be able to fly 1,000 miles a day — further than the distance from Utqiagvik to Anchorage.
However, Arctic terns do not fly in a straight path from the Arctic to the Antarctic. Instead, they will regularly stray off course in search of the best weather and the best food. Although they will usually return to the same nesting ground each year, occasionally a tern will go to a new spot. For example, it has been recorded that some Arctic terns from Greenland were later spotted in Australia!
Arctic terns have long lifespans and typically live to be between 20 - 30 years old. One Arctic tern was recorded living to be age 34. By the end of their life, an average individual Arctic tern may have flown 1.5 million miles, the equivalent of traveling around the Earth 60 times.
Watch this video to watch some Arctic tern migration patterns…
DIET
Arctic terns primarily eat small fish, such as herring. They will also eat small invertebrates and insects. Rarely, they will eat berries.
They forage by hovering over the water, then plunging down and grabbing a fish in their beak. They are not strong swimmers, and will typically only stay in the water for as long as it takes to grab a fish.
CULTURAL SIGNIFICANCE
Inuit and Inupiat eat the eggs of Arctic terns. The eggs are mostly boiled, but can also be fried or eaten raw. Most of the egg collecting happens during a two-week window in early July. They rely on the birds’ presence to serve as indicators of environmental conditions — the presence of Arctic terns in early summer indicates that warm weather is coming. Arctic terns diving at sea can also be an indicator of good fishing areas.
Arctic Tern COLORING SHEET
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Information obtained from: University of British Columbia, The Audubon Society, Alaska Department of Fish & Game, National Wildlife Federation, Juneau Empire, Alaska Guide, Plos One, and National Library of Medicine.
