The cute Arctic tern is a bird in the family Laridae, which contains gulls, terns, noddies, skimmers and kittiwakes. They have a circumpolar breeding distribution, crossing the Arctic, Sub Arctic Europe, Asia and North America. By the standards of other terns, the Arctic tern is very oceanic, spending a great deal of their time at sea.
Long distance travel: the amazing migration of the Arctic Tern
The Arctic Tern has one of the most impressive migrations on Earth. In the northern summer, they spend their time in the cooler, more temperate parts of North America, and in the southern summer they are almost entirely marine birds, reaching as far as the northern edge of the Antarctic ice. They hatch during the summer in the Arctic circle, and as the cold Arctic winter approaches, they fly south to chase the summer season all the way to the Antarctic circle. Arctic Terns don’t actually fly in a straight line from pole to pole, but instead make several detours, and so the 12,000 mile distance from Arctic to Antarctic is actually a much longer trip. On average, the migration ranges from 44,000 to 59,000 miles, making it one of the longest migrations on earth! As they chase the summer sun, Arctic Terns are likely to experience more sunlight than any other animal on earth! When scientists fit Arctic Terns with GPS trackers, they found that they will fly thousands of miles out of their way to take advantage of the best weather and food resources.
The epic migration of the Arctic Tern (image from BBC news)
The huge amount of time spent in sunshine allows Arctic Terns to see fish and insects more clearly against the oceans, and the summer months also provide calmer weather, so much easier for the birds to fly. Arctic Terns are very lightweight and so they can cruise on ocean breezes over incredible distances without flapping their wings once, saving vast amounts of energy. They will also sleep and eat whilst on these long glides, and like hummingbirds, they are one of the few birds that can hover in midair.
Arctic tern parents feeding their offspring in a breeding colony (image from the BC Bird Breeding Atlas)
Arctic Terns mate for life and usually will find their way back to the same breeding colony, often on the coast, each year. Their courtship routine is pretty elaborate, starting with a behavior called ‘high flight’, which involves the females chasing the males up to high altitude, then slowly descending. After this, the males will conduct fish flights, where the male catches and offers fish to the female. Once eggs have been laid, both males and females will defend the nest, and the male will collect food for the female. A few days after hatching, chicks can move around and explore their surroundings. Arctic Terns use something called a ‘K selection strategy’, which involves the species investing more heavily in fewer offspring, increasing effort but also increasing the chance of survival to adulthood.
A stable future?
The IUCN red list currently lists the Arctic Tern as least concern, and in general their populations are believed to be relatively stable. However in the Southern part of their range, it has been noticed that their numbers are dropping, largely due to a lack of food. There is also the potential that climate change could cause a loss of 20-50% of their habitat, and could also affect the distributions of their prey species in the ocean. Fortunately, as they have a very large breeding range, any loss of habitat that could cripple another species is less likely to affect the Arctic Tern. If an area begins to lose food resources, the Arctic Terns can simply move to another region. This does make the Arctic Tern a very useful animal as a control in studies on the effects of climate change or habitat loss.
In some breeding colonies, there are risks from predation by cats and other feral, invasive species. In some places, the invasive mink is also a concern for many nesting bird species, not just the Arctic Tern, although control measures are helping to reduce the risks from this.
Although the Arctic Tern is not in urgent need of conservation attention right now, many other birds do need interventions to support their future. The National Audubon Society is a not for profit organization leading bird conservation in the U.S, and you can learn about their bird conservation initiatives, including tackling climate change and invasive species, here: National Audubon Society
Awesome videos!
References
Arctic Tern Identification, All About Birds, Cornell Lab of Ornithology
Fijn, R.C. Hiemstra, D. Phillips, R.A. van der Winden, J. (2013) ‘Arctic Terns Sterna paradisaea from the Netherlands migrate record distances across three oceans to Wilkes Land, East Antarctica.’ Ardea
Hansen, K. (2001) ‘Threats to wildlife in Greenland.’ Seabird Group Newsletter
Hawksley, O. (1957) ‘Ecology of a breeding population of Arctic Terns.’ Bird Banding
Mason, I. (2010) ‘World’s longest migration found: 2X longer than thought.’ National Geographic Society
Moller, A.P. Flensted-Jensen, E. Mardal, W. (2006) ‘Dispersal and climate change: a case study of the Arctic Tern Sterna paradisaea.’ Global Change Biology
Redfern, C.P.F. Bevan, R.M. (2020) ‘Use of sea ice by Arctic Terns in Antarctica and impacts of climate change.’ Journal of Avian Biology
Sterna paradisaea (Arctic Tern) (iucnredlist.org)
MASSIVE THANK YOU TO RACHAEL DA SILVA FROM THE UK FOR THIS WRITE UP! PLEASE FOLLOW HER ON INSTAGRAM AND HER WILDLIFE ARTWORK AT TILLY_MINT08
