Where the wind blows: seabirds of the sub-Antarctic islands

For more than twenty years, Paulo Catry, a researcher at MARE ISPA, has returned every year to the Falkland Islands to monitor the life of black-browed albatrosses. The long-term study he has built up has become an international benchmark and reveals how the Southern Ocean is changing in the face of climate change, disease and human pressures. 

It was in 2002 that Paulo Catry made his first trip to the Falklands (also known as the Malvinas), a remote archipelago in the South Atlantic, consisting of more than four hundred islands with a cold, windy and dry climate. Only a small part is inhabited, while the rest of the territory remains virtually untouched, with rocky coasts, plateaus of low vegetation and vast colonies of birds and marine mammals. Their isolation, abundant fauna and proximity to the Southern Ocean make them one of the most important places in the southern hemisphere for the study of sub-Antarctic ecosystems.

At the time, he was invited by colleagues to carry out the first population estimate of the slender-billed prion (Pachyptila belcheri), whose colony on New Island (one of the Falkland Islands) proved to be the largest in the world. It was the first step in a long-term project that continues today. Among penguins, sea lions, fur seals and many other species, Paulo asked to work with black-browed albatrosses, a species of seabird whose largest population is found in the Falklands.

From then on, the research never stopped. ‘We have a pool of about 500 adult individuals that are individually marked, and every year we go and see how they are doing. They are very long-lived animals, and this investment gains value as the study continues,’ he explains. This strategy allows for the study of survival, reproduction, behaviour, movements at sea and reactions to environmental changes with a rigour rarely seen in the study of seabirds.

The project has been consistently supported by the Falkland Islands Government, with additional funding from national (including the Science and Technology Foundation) and European projects involving British, French and American universities and institutes, as well as local partners, students and volunteers who take turns in the fieldwork from October to the end of February. The result is one of the most comprehensive time series in the southern hemisphere on a wild population.

Where the wind dictates the pace 

Environmental and logistical conditions shape the research as much as the data itself. Getting to the study site can take between five and ten days and depends on scarce connections and difficult weather conditions. ‘There have been times when it was just me and the pilot,’ he recalls. Small planes connect the islands, and in bad weather, flights are cancelled for several days. ‘It's very challenging because the trips are very difficult, they take a long time, and bad weather can prevent us from reaching an island, or even worse, from leaving the island,’ Paulo confesses.

On the ground, the wind is the dominant force. ‘Two or three degrees with strong winds is nothing compared to our experience here. Sometimes it's even difficult to stay on our feet.’ But despite the adverse conditions, the relationship with the fauna is extraordinary. "The animals are practically unafraid of people. The albatross is in its nest and we can walk up to it, grab it or measure the egg without it running away,‘ he says. ’We have thousands of sea lions, a hundred thousand penguins and almost half a million albatrosses. We've had to push sea lions away to get to the sea. It's a very different and very funny experience," he confesses. 

Living in the Falklands is not for everyone either. Although most places have minimal infrastructure, which may include a house with solar power and water sources, there are islands where this is not the case: ‘there we have to camp in the cold and bring everything with us. But these stays are usually short, lasting one or two weeks.’ For emergencies, there is only one satellite phone and no internet access.

What albatrosses reveal about a changing ocean

Data accumulated over the years has made it possible to identify interesting patterns linking environmental conditions and bird welfare. During the first half of the study, ‘a positive demographic trajectory was observed, as there was a major effort to reduce accidental catches associated with industrial fishing.’ But the trend is changing, and in recent years conditions have deteriorated, making the trajectory negative, albeit not very rapidly.

The correlation between environmental factors and the status of the black-browed albatross population has allowed other curious facts to be documented. Albatrosses usually form pairs for life, but they also divorce, although the rate is small. In addition, it is known that the probability of divorce is higher when reproduction is unsuccessful. However, Paulo Catry and his team, when analysing the time series available to them, found something surprising: ‘in years when sea water temperatures are higher and conditions are more difficult, these birds divorce more frequently,’ a result that suggests how climate change may impact these populations in the future. This was the first time anyone had documented this result in birds. 

Threats beyond climate change

In addition to climate change, sub-Antarctic birds face other threats.

The global bird flu crisis, which began spreading in Europe about three years ago and has now reached every corner of the globe, recently arrived in the Southern Ocean. Paulo Catry's team, together with other researchers, has been studying the impact of this disease on another species: skuas. These are predatory and scavenging birds that consume the carcasses of other birds potentially infected with viruses, bacteria and other pathogens, making them particularly vulnerable to disease. A very similar species in Europe has seen three-quarters of its population in the British Isles die from the disease.

But in Antarctica, despite infection rates of close to 100 per cent, mortality has been surprisingly low. Paulo Catry's hypothesis is based on the behavioural ecology of these birds: ‘These auks in the South Seas are more dependent on predation and scavenging, and it is possible that these birds invest more in their immune system because, due to their lifestyle, they are more exposed to pathogens,’ which will make them more resistant to disease.  

But the greatest threat to birds, according to the researcher, will probably be fishing, both targeted and incidental, along with another factor: the introduction in the past of species such as rats and cats to these oceanic islands.

The message that remains

For Paulo Catry, Antarctica is, above all, “wild”. His work shows how the Southern Ocean already reflects the effects of climate change and fishing pressure, revealing rapid changes in a sensitive ecosystem.

The most memorable moment of his experience remains his first arrival in the field and his close contact with animals that show no fear of humans.

He considers it essential that Portugal and MARE maintain a presence in the region, a true ‘canary in the coal mine’ where global changes become visible and raise public awareness about the state of the planet.

He leaves a simple message for his readers: ‘It's worth a visit.’

Written by Vera Sequeira and Joana Cardoso

Photographs by Paulo Catry