HAGRG biologist Isabeau Pratte releases a just-tagged tern on Nasaruvaalik Island in the Canadian High Arctic. You can see the small black tag attached to the bird's left leg.
Arctic terns famously undertake the longest migration in the animal kingdom, travelling over 90,000 km per year between their breeding grounds in the Arctic and their wintering grounds around Antarctica. While past studies have revealed the amazing migrations of individual birds from several different breeding areas, we still lack a clear understanding of how the world population of Arctic terns is structured. Many species such as Arctic terns which breed across a vast circumpolar range are often actually made up of distinct sub-populations which breed in specific areas, travel along unique migratory routes, and winter in restricted pockets of the larger range occupied by the species as a whole. Information on the population structure of such species is critical if we are to make informed conservation decisions.
An Arctic tern on its nest at Nasaruvaalik Island, NU
Arctic terns are a common species in many parts of the Arctic, but over the last few decades, scientists from all over the north have been noting slow but steady declines in breeding populations. These declines have not been satisfactorily explained, and a necessary first step is to figure out where the problem seems to be - is it an issue with conditions around breeding sites (reduced foraging opportunities, increased predation, etc...) or does the problem lie at the other end of the world, affecting birds wintering in the Southern Ocean? Before we can answer these questions, we first need to get a better idea of where Arctic terns are actually spending their time when they are not breeding - a 9 to 10 month period during which time they are far out at sea in some of the most inhospitable parts of the planet.
In order clarify the population structure of Arctic terns in North America and learn more about where these birds are wintering and how they get there, the High Arctic Gull Research Group, in collaboration with the Smithsonian Institute Migratory Connectivity Project and partners across North America, have undertaken a multi-year project to track Arctic terns from all across North America. From Alaska to Nova Scotia, from the High Arctic to the Maritimes, HAGRG collaborators have deployed 124 tracking tags at birds from 6 different colonies. Despite challenging conditions in 2017, the deployment phase of the project was an amazing success! In 2018, scientists will return to the same colonies to try and recover the tags which will have recorded an entire year's worth of data on the movements of each bird. For now, we wish our feathered friends safe travels, fair winds, and following seas.
The breeding range of Arctic Terns in North America is shown in orange. Red stars indicate colonies where HAGRG collaborators deployed tracking tags in 2017.