On track to map seabird populations
Recent developments in tracking technology allow scientists to monitor seabird populations in greater depth than ever before. Researchers in the SEATRACK programme are working to map the non-breeding distribution of seabirds across the North Atlantic Ocean, with the aim of understanding their distribution at sea all year round, as Hallvard Strøm explains.
A wide variety of seabirds can be found across the North Atlantic, including gannets, puffins and guillemots. While long-term studies have been conducted on these birds while they are breeding in colonies, less is known about what happens after the breeding season when they leave their colonies. “We lack knowledge about what they do after they leave the breeding colonies – usually in late Summer – until they return in the following Spring or early Summer. So we lack knowledge about most of their life-cycle,” outlines former project leader (2014-2024) Hallvard Strøm and member of the SEATRACK project group. This is an issue researchers in SEATRACK aim to address. “We are working to map the nonbreeding distribution of seabirds on the North Atlantic scale,” explains Strøm. “We want to understand how these seabird populations move, so we need to monitor many colonies and species, over many years.”
Tracking seabirds
The development of new technologies like Global Location Sensors (GLS) and the Global Positioning System (GPS) has opened up new possibilities in this respect, making it significantly easier to track seabirds and gather data on their behaviour. The GLS logger is not particularly precise in terms
“We are working to map the non-breeding distribution of seabirds
on
the
North Atlantic scale.
We
want to understand how seabirds are distributed at sea all year round and how their distribution may change through time, so we need to monitor many colonies and species, over many years”
of pinpointing the location of seabirds, but Strøm says it has other attributes that make it suitable for large-scale studies on species migrating over longer distances. “It is very light – some models weigh less than a gram. They are relatively affordable and they have very little – if any – effect on the birds. They can also carry other sensors that can be used to understand other aspects of the birds’ behaviour,” he says. “These loggers are now
being used to track 16 of the most common species of seabirds in the North Atlantic.”
Alongside looking for species representative of different ecological groups (e.g. those feeding exclusively at the surface or those diving deep), Strøm and his colleagues also needed to take account of practical concerns.
“We needed to find birds which are suitable for these kinds of tracking studies. We needed to be able to catch them, and re-catch them, and
to make sure that they can carry a logger and so on,” he points out. It is also important that the selected species have a wide distribution and don’t breed in just one place. “We started out by selecting colonies of seabirds in the North-East Atlantic, then we expanded to include Greenland and Canada,” says Strøm.
“Now we have moved on to include Swedish, Danish and German colonies and others in the West Atlantic, as well as colonies in France, Finland, Iceland, Norway and the UK.”
This is a large-scale international collaboration between more than 40 institutions from 14 countries. The project covers a vast area, from the North American coastline right across to the Barents sea, with Strøm and his colleagues looking at data on migrating seabirds from more than 80 sites. There are different hypotheses about why seabirds migrate; in the case of Arctic species, one of the main reasons is to maintain their food base. “They have to migrate out of the Arctic, to get out of the Winter darkness and away from the sea ice, which moves South during Autumn and Winter. Daylight is also an important factor,” explains Strøm.
The different species migrate over varying distances, and Strøm says other variations in their migratory strategies have been
The Seabird population in the North Atlantic is under significant threat, with commercial fisheries, pollution, the presence of alien invasive predators and habitat degradation all contributing to increased vulnerability.
There are thought to be over 350 species of seabirds, some 31 percent of which are classified as threatened by the International Union for the Conservation of Nature, while others are not far off the same classification.
The picture in the North Atlantic is stark, with a dramatic decline in the population of several different species, including gannets and puffins, while breeding sites are also under threat, underlining the importance of monitoring and preservation.
observed. “We’re looking at a very diverse group of species. Some migrate over large distances before they stop and feed, while others stop regularly on their journey. Some migrate alone or in small groups, while others move in larger groups,” he outlines. The project team is also looking into whether birds change their migration strategies over time, which to some extent seems to depend on their age. Younger birds seem to migrate over longer distances, then when they establish themselves as adult breeding birds more stable patterns tend to emerge. “Then they tend to go to the same area repeatedly,” says Strøm. However, climate change is leading to shifts in fish distribution, which may then affect seabirds, an issue Strøm plans to look into in greater depth in future. “As the food base essentially starts to move, it may be that seabirds need to move as well. That may be possible for some species, but not others,” he outlines. “That’s something we would like to look into, to see if we can see changes in seabird distribution over time.”
Industrial development
This research holds wider importance in the context of industrial development in certain
Razorbills and Atlantic puffins
Credit: Svenja Neumann
Logger deployment
Credit: Paul Thompson
SEATRACK field sites throughout the North Atlantic. Russian colonies are not included in phase III (2023-2026) of the program (white dots).
Northern fulmar
Credit: Sébastien Descamps, Norwegian Polar Institute
Common eider Credit: Børge Moe
Seabird field work
Credit: Sébastien Descamps, Norwegian Polar Institute
Se ATr ACk
Seabird Tracking
Project Objectives
SEATRACK aims to map the non-breeding distribution of seabird breeding in the North Atlantic and understand how changes in environmental conditions affect demography and population trajectories. This includes colonies in Canada, Greenland, Norway incl. Svalbard and Jan Mayen, Iceland, the Faroe Islands, Ireland, the Netherlands, France, Germany, Finland, Sweden, Denmark, and the United Kingdom.
Project Funding
Funding is currently provided by the Norwegian Ministry of Climate and Environment, the Norwegian Environmental Agency, the Norwegian Ministry of Energy, the Norwegian Coastal Administration, and Offshore Norge along with 16 energy companies (Equinor, WintershallDea, AkerBP, Total, Shell, OKEA, Sval, Neptune, Vår, ConocoPhillips, Vårgrønn, Fred. Olsen Seawind, Hafslund Vekst, Ørsted Norge, NorSea Group and Statkraft).
Project Partners
SEATRACK is led by a project-group with representatives from the Norwegian Polar Institute (NPI) and Norwegian Institute for Nature Research (NINA). • Benjamin Merkel – PI, Project group (NPI) • Hallvard Strøm – former PI, Project group (NPI) • Sébastien Descamps – Project group (NPI) • Børge Moe – Project group (NINA) • Per Fauchald – Project group (NINA) • Arnaud Tarroux – Project group (NINA) • Svenja Neumann – Project coordinator (NPI) • Vegard Sandøy Bråthen – Project engineer (NINA) • Caitlin Frankish – Postdoc (NPI).
Contact Details
Principal Investigator (2014 - 2024) Hallvard Strøm, Section Leader, Principal Investigator (2024 onwards) Benjamin Merkel, PhD, Researcher, Norwegian Polar Institute, Fram Centre, Tromsø, Norway
T: +47 93245868
e: hallvard.strom@npolar.no
e: benjamin.merkel@npolar.no
W: https://seapop.no/en/seatrack
Hallvard Strøm is Head of Section of the Terrestrial Ecosystem and Seabird Section in the Norwegian Polar Institute. His research is focusing on seabird population dynamics, movements, and ecotoxicology. He has been the PI of SEATRACK since the start in 2014.
Dr Benjamin Merkel is a Research Scientist at the Norwegian Polar Institute. His research interests include the study of animal movement, in particular migration, and its significances for ecosystem dynamics. He took over the lead of the SEATRACK project in 2024.
parts of the oceans, part of the blue growth agenda, with the Norwegian government keen to encourage growth in the maritime sector. One aspect of this is the development of offshore wind farms, which represent an important potential source of renewable energy, yet it’s also important to consider the impact of these facilities on seabird populations. “One major impact of wind farms is an increased risk of collisions. They may also effectively force seabirds away from their feeding areas,” explains Strøm. The SEATRACK project plays an important role in this respect by providing more detailed information on seabird distribution at sea, which is a major step forward. “We can now tell what species are using certain areas and during which period of the year. Before we had this tracking data we would have to go out by boat to see what species were there,” says Strøm.
This data is being made available through web applications, enabling stakeholders to look at which populations and species use certain areas of the oceans, which can then be taken into consideration in marine spatial planning. Seabird feeding areas and migration corridors are likely to change further over time, so Strøm and his colleagues plan to continue this work in the future and build a deeper picture. “We want to monitor these long-term changes,” he says. The hope is to replace GLS loggers with GPS ones in future, which will provide a higher level of accuracy.. “It’s also possible to include a number of sensors in the logger. We would like to include an accelerometer for example,” continues Strøm. “We will also be able to fill gaps in the record with the GPS logger, it would take the birds’ position regularly, throughout the year.”
The availability of detailed tracking data means researchers can now tell which seabird populations actually use an area, at what time of year, and where they come from. While it might be assumed that the main users of Norwegian waters are Norwegian seabird populations, Strøm says the data from just off the coast shows a different picture. “We see that many populations from all our neighbouring countries use this area for most of the year,” he outlines. In general, seabirds have been found to use much larger areas than had previously been thought, which needs to be taken into account in marine spatial planning as industries develop. “A number of new industries are developing, like offshore wind and mineral extraction from the sea bottom,” continues Strøm. “It’s really important to have detailed knowledge about how seabirds use the marine areas in this respect, and how this is changing in the context of the changing climate.”
Dr Benjamin Merkel
Black-legged kittiwake with GLS logger Credit: Morten Ekker
Bjørnøya Credit: Benjamin Merkel, Norwegian Polar Institute