Seabirds in the eye of the storm

Like all animal species, seabirds must be well adapted to their ecological niche in order to survive. Environmental conditions such as temperature, vegetation, precipitation and many other factors influence natural selection: whoever is best adapted survives. Previous research has focused a lot on how the animals can cope with the rising temperatures. However, seabirds are also exposed to gale force winds, as they usually go hunting on the open sea.

The first author of the study, Elham Nourani from the Max Planck Institute for Animal Behavior, asked herself how the birds react to cyclone-force winds and what maximum wind speeds they tolerate. Using flight data from 18 different species, she and her team also investigated whether the species avoid certain wind speeds depending on their flight characteristics.

Faster than the wind: data reveals flight characteristics

The team used GPS tracking technology and analysed more than 300,000 hours of flight. This allowed them to show that birds living in windier environments fly faster than the wind. "They need to reach these speeds to be able to determine their own direction. Otherwise they would simply drift away," explains co-author Emily Shepard. In their analyses, the researchers looked at tropical species and albatrosses, among others.

Albatrosses are fast flyers, as they regularly fly in storms in the southern ocean. Tropical species, on the other hand, experience lower wind speeds every day and only very rarely high wind speeds and are adapted accordingly. "However, tropical storms are much more intense than those in the southern ocean," says Shepard. This means albatrosses can fly in almost all conditions, while tropical species have to develop special strategies avoid strong winds. Tropical storms reach twice the speed of what the birds would tolerate. "What is extreme wind for a tropical species is commonplace for an albatross. So what extreme conditions are varies by species," says Nourani.

But just because albatrosses can fly in many winds does not mean they do: Sometimes they fly right into the eye of the storm, like an Atlantic yellow-nosed albatross they tracked in this study. While the wind speed within the storm was 68 kilometres per hour, it was only 30 in the eye of the storm, so the bird could fly in it for twelve hours. What was particularly unexpected for the researchers was that the birds sometimes avoided wind speeds at which they could fly in other scenarios. They suspect that this is a strategy the birds use to avoid going off course. The results of the study can help to better assess which seabirds can withstand the rapid change in storm intensities in the future.