Can seabirds hear sounds across the ocean?Our research shows this

Animals move amazing distances in search of food. Caribou, reindeer and wolves cover impressive distances over land, while seabirds fly unparalleled distances. Arctic terns travel from the Arctic to Antarctica and back every year. Wandering albatrosses (Diomedea exulans) make the equivalent of ten trips to the moon and back in their lifetime.

Much research has been done on how seabirds choose flight paths and find food. They appear to use sight or smell to assess local conditions.

However, wandering albatrosses can fly more than 10,000 kilometers on a foraging trip, and we don’t know much about how these birds use mid- to long-range cues in the environment to decide where to go.

However, my team’s recent research provides the first insight into how birds such as wandering albatrosses use sound to determine what’s going on at greater distances.

How seabirds use low-frequency sounds

Previous research has shown that seabirds seek information not only about where to find food, but also how to find it efficiently. We found that the way wandering albatrosses use sound may be crucial.

Our research looks at how these birds respond to a type of low-frequency sound called infrasound, which can travel thousands of kilometers.

Although humans generally cannot hear infrasound waves, we know that some animals can hear them. When waves crash together or hit the shoreline, they produce an infrasound frequency called micropressure. This is the type of infrasound we study.

We know that areas of high wave activity can be related to upwellings that bring fish to the surface. Infrasound can provide information about the location of these areas and tell birds about good feeding areas.

Efficient foraging is particularly important for large seabirds such as wandering albatrosses with a wingspan of 3.5 meters. Their size means they rely on wind to take off and fly efficiently, unlike smaller birds such as puffins, which flap their wings up to 400 times per minute.

High wave activity also indicates strong winds. Given that we know that wandering albatrosses rely on wind to fly efficiently, my team’s research suggests that infrasound can provide them with long-range cues about optimal foraging conditions.

Infrasound is also produced when waves hit the coastline, and we know that many coastal seabirds use the coast to choose their flight paths and find their way back to their breeding grounds. As a result, infrasound can reveal the location of static features such as coastlines, providing seabirds with important information over long distances.

Despite the potential of this cue for seabirds, our paper (published in Proceedings of the National Academy of Sciences) is the first evidence that seabirds may respond to infrasound, which is monitored globally through a network of sensors installed by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO).

The system was installed to detect nuclear tests, but its byproduct is a wealth of data that scientists can use. We combined the CTBTO records with our own GPS tracking data of 89 wandering albatrosses to compare microbarometric pressure and the birds’ movements.

what we learned

This allowed us to isolate data showing how these albatrosses seemed to decide where to go next. Our results show that they chose the direction where the infrasound waves are largest. This suggests that birds may use infrasound to find food or minimize the energy they use during travel. However, we couldn’t determine why the louder areas were better.

Our results may also provide scientists with insights into how other birds make decisions during mid- to long-distance travel.

Like many studies that test hypotheses for the first time, my team’s study raises as many questions as it answers. If seabirds respond to infrasound, they must be able to hear it and know where it is coming from. Laboratory studies have found evidence that some birds can hear infrasound waves, but seabirds have not yet been tested.

Bringing a wandering albatross into a lab and creating a sound chamber large enough for experimental testing seems unlikely in the short term, but other seabird species can live in captivity and research could be focused there.

For example, weather changes caused by climate change, and the devastating effects these changes have on seabirds and many other plants and animals, make it harder for them to find food.

As humans alter ocean habitats, infrasound could help birds find food, helping them adapt even as populations decline. Or human activities, such as more noise, could obscure such important messages, with harmful consequences for wildlife. Either way, understanding how and why seabirds use infrasound will help scientists understand the importance of infrasound in the climate crisis.

This article is republished from The Conversation under a Creative Commons license. Read the original article.