A study led by researchers at Bangor University reveals the sophisticated decision-making Manx shearwaters make to find fish at sea.

By measuring the effort it takes shearwaters to fly in different wind conditions, Dr Stephanie Harris and colleagues discovered the birds decide where to fly to find fish based on the wind, carefully balancing the energy gained from food with the energy spent searching for it.

Research shows on windy days shearwaters look for food in places it is easier to fly to. On calmer days they favour places they anticipate will be good for finding fish.

Dr Harris said: “Seabirds are faced with a huge ocean in which to find food, and being able to plan where to go is important.

“The implication is that shearwaters do have a plan for where they are going to feed, and also have a rough idea of how much it will cost in terms of energy to get there depending on the wind”.

Research took place at Bardsey Bird Observatory in North Wales and Copeland Bird Observatory in Northern Ireland. These islands are important breeding sites for Manx shearwaters.

This study was made possible by the most up-to-date miniaturisation of tracking technology to follow seabirds in their natural environment – far at sea.

Dr Harris added: “Using devices that weigh as little as 7g, we can not only follow where a bird goes, but measure its every wingbeat during flight, using technology similar to that found in a smartphone”.

Senior author Dr Line Cordes, formerly based at Bangor University and now at the Norwegian Institute for Nature Research (NINA) said: “Climate projections forecast reductions in summer winds around the UK. Understanding the role of winds in how seabirds forage will be crucial to understanding the impact this will have on seabirds.”