The size and weight of arctic terns allow them to undergo remarkable feats such as flying enough miles to make it to the moon and back three times in their lifetime! The species has undergone thousands of years of evolution to become the fascinating creature we see today. So just how big is the arctic tern?
Arctic terns are 28-39cm (11-15″) in length and they weigh 90-120g in weight (3.2-4.2oz). They are slim, medium-sized seabirds and one of the smallest members of the Tern family. Their wings are long and narrow with a wingspan of 64-76cm (25-30 inches) which makes them perfectly suited for gliding.
Keep reading to find out how the arctic terns’ size and weight compare to other terns and seabirds, how much chicks grow each day after hatching, and why the arctic terns’ wingspan is crucial to their migration!
How Big Are Arctic Terns?
Arctic terns are medium-sized, slender seabirds that measure 28-39cm (11-15 inches)1 (source: Cornell University). Male terns also tend to be slightly larger than females, however, sexual dimorphism (where one sex is substantially larger than the other) is not profound2 (source: C.M. Devlin, Waterbirds, Vol. 27, No. 3, pp. 314-320, 2004).
Whilst the arctic terns are slender in build, they have no fear of dive-bombing threats that are much larger than them such as humans when protecting their nests and hatchlings.
The arctic terns also have small heads, short legs, and slim bills3 (source: J. Carter, S.C. Brown, Arctic Wings, 2006). The arctic terns’ slim bills are suited to their diet of small fish such as cod and herring.
What is the Wingspan of an Arctic Tern?
All birds have varying wing sizes and shapes according to their needs for survival.
The arctic tern needs a pair of wings that are perfect for gliding over large distances for long periods, this is because they migrate from the north to the south pole and back again every year, totaling approximately 50,000km a year.
The wings of an arctic tern have a ‘high aspect ratio. This means they have long, narrow wings that allow them to glide along with the wind and use up very little energy4 (source: National Geographic).
The wingspan of the arctic tern can range from 25-30 inches (64-76cm) and are lighter than that of the common tern which has a wingspan of 30-90 inches (77-98cm)5 (source: National Wildlife Federation). This is partly because arctic terns migrate a much further distance than the common tern6 (source: W.R. Meservey and W.R. Petersen, Massachusetts Breeding Bird Atlas, 2003).
See below for more wingspan comparisons with other seabird species.
Arctic Tern Wingspan vs Other Seabirds
|Shearwater||50-70cm (20-28 inches)|
|Puffin||50-60cm (20-24 inches)|
|Murre||60-75cm (24-29 inches)|
|Arctic Tern||64-76cm (25-30 inches)|
|Seagull||60-160cm (24-63 inches)|
|Albatross||183-335cm (72-132 inches)|
How Much Do Arctic Terns Weigh?
Adult arctic terns weigh 90-120g (3.2-4.2oz)7 (source: C. Egevang, et al., Proc Natl Acad Sci U S A, Vol 107, No. 5, pp. 2078-2081, 2010). The arctic terns’ light weight helps them avoid any hindrances to aerodynamics. It also permits them to be carried across large distances by the wind which decreases their energy loss.
How Much do Chicks Weigh?
When arctic tern hatchlings emerge from their eggs, they tend to have a body mass of approximately 13.1g (0.5oz)
Following hatching, the chicks grow very quickly with an increase in body mass of 5.3g (0.2oz) per day8 (source: J.E. Østnes, et al., Polar Research, Vol. 16(1), pp.1-8, 1997). This rapid increase in body mass is vital to the arctic terns’ survival.
Just 3 months after hatching the chicks need to be ready to embark on a long migration from the northern hemisphere to the southern hemisphere of the earth!
How Big Are Arctic Tern Eggs?
There is an ongoing, discussion on whether larger eggs result in larger and fitter hatchlings. However, it is difficult to track eggs from hatchlings to adults without any confounding factors; a consensus has not been reached on the matter.
Size of Arctic Terns vs Other Birds
The arctic tern is one of the smaller tern species, especially when compared to Caspian terns which is the largest tern in the world and can reach a bodyweight of 700g.
Arctic terns are of similar size to the common tern from which the arctic tern often boldly steals food in acts of kleptoparasitism. As a result, they admirably stay true to the phrase ‘pick on someone your own size’.
See more size comparisons between tern species below.
Tern Species Size Comparison
|Type of Tern||Length||Weight|
|Least Tern||23cm (9")||45g|
|Arctic Tern||28-38cm (11-15")||90-120g|
|Common Tern||30-36cm (12-14")||110-141g|
|Inca Tern||41cm (16")||180-210g|
|Caspian Tern||48-56cm (19-22")||500-700g|
|White Tern||76-86cm (30-34")||92-139g|
The arctic tern is smaller and lighter than most seabirds, including seagulls, murres, and shearwaters. Even the puffin, which is similarly sized to the arctic tern, weighs more than three times as much.
See the arctic tern size comparisons with other seabird species below.
Arctic Tern Size vs Other Seabirds
|Type of Seabird||Length||Weight|
|Arctic Tern||28-39cm (11-15")||90-120g|