Ecology : Storms leave seabirds starve
In winter hundreds or thousands of emaciated seabirds end up on the beaches of Europe or North America. Storms are also to blame. However, they do not kill directly. by Daniel Lingenhöhl © David Grémillet, La Rochelle University (detail)
In January and February 2019, thousands of dead guillemots drove to the coasts of the Netherlands: starved to death on the open sea. Mass deaths like this happen again and again, and in many cases storms are considered to be triggers. A team led by David Grémillet from the French CNRS has investigated whether and how severe storms affect the birds and published the study in “Current Biology”.
The group had provided 1500 animals of five common seabird species such as puffins, guillemots and razorbills with small data loggers and compared their movements with the trails of winter storms. In winter, many seabirds move south from their arctic breeding areas, for example to the North Sea, in order to escape the harsh conditions of the far north. On their way & nbsp; – or in the wintering areas themselves & nbsp; – the birds get caught in storms again and again, which ultimately become their undoing.
However, the animals rarely die directly from the cyclones, and they also do not die from the increased expenditure of energy that they might have in the hurricanes. At least that is what models of their energy consumption in bad weather suggest, as Grémillet and Co write. Instead, the animals starve to death because they can hardly or not at all search for food if they are caught in the middle of a storm: the species examined fly relatively poorly, especially in strong winds. Others cannot dive for food when the sea is churned. If the storms last too long or come back too often, the animals starve to death in large numbers in the open sea.
Because of global warming and overfishing, many seabird species are already under pressure. Important food fish, for example, migrate to deeper and therefore cooler water layers or are fished in large numbers. Should storms become more frequent or more intense in the future, the populations of many seabirds could continue to shrink because the cyclones claim many victims.