Animals travel surprising distances in search of food. While caribou, caribou and wolves travel impressive distances on land, seabirds are unrivaled in the distance they travel. Arctic terns travel from the Arctic to Antarctica and back as part of their annual migration. wandering albatrosses (Diomedea exulans) fly the equivalent of ten times to the Moon and back in their lifetime.
Much research has been done on how seabirds choose their flight paths and find food. They appear to use their sense of sight or smell to assess local conditions.
Wandering albatrosses can travel more than 10,000 km in a single foraging trip, and we don’t know much about how these birds use medium- and long-term cues from their environment to decide where to go.
But my team’s latest work provides an insight for the first time into how birds such as wandering albatrosses can use sound to identify conditions further away.
How do seabirds use low-frequency sound?
Previous research has shown that seabirds seek information not only about where to find food, but also how to do so efficiently. We discovered that the way wandering albatrosses use their sense of sound can be very important.
Our study examined how these birds respond to a type of very low-frequency sound called infrasound, which can travel thousands of kilometers.
Although it is not usually heard by humans, we know that some animals can hear infrasound. When waves hit each other or the shoreline, they create an infrasound frequency called microbarum. This was the type of infrasound our study examined.
We know that areas of high wave activity can be associated with upwellings where fish come to the surface. Infrasound can provide information about where these areas are and inform birds of good foraging areas.
Effective foraging is particularly important for large seabird species such as the wandering albatross, which has a wingspan of up to 3.5 metres. Their size means they rely on wind to take off and fly effectively, unlike smaller birds such as seagulls, which flap their wings up to 400 times per minute.
High wave activity is also indicative of strong winds. Given that we know that wandering albatrosses rely on wind to fly effectively, my team’s work suggests that infrared sound may give them a long-range clue as to where optimal foraging conditions might be.
Infrared sound is also produced when waves crash against the shoreline, and we know that many coastal seabirds use the shore to select flight paths and find their way back to their breeding colonies. That means infrared sound can reveal the location of static features such as shorelines and give seabirds important information over long distances.
Despite the potential of this cue for seabirds, our paper (published in PNAS) provides the first evidence that seabirds can respond to infrared sound monitored globally through a network of sensors established by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). .
This system was set up to detect nuclear testing, but the byproduct of this is a huge amount of data available to scientists. We combined CTBTO’s recordings with our own GPS tracking data from 89 wandering albatrosses to compare microbarums and the birds’ movements.
What did we learn?
This allowed us to isolate data showing how albatrosses make decisions about where to go next. Our findings showed that they chose the direction with the loudest infrared sound. This suggests that birds may use infrasound to find food or minimize the energy they use during their travels. But we can’t say for sure why louder areas are better.
Our findings may also give scientists insight into how other birds make decisions on medium- and long-distance journeys.
As with many studies that test a hypothesis for the first time, my team’s work raises as many questions as it answers. If seabirds respond to infrared sound, they should be able to hear it and know where it’s coming from. Laboratory studies have found evidence that some birds can hear infrared sound, but no tests have been done on seabirds.
Bringing a wandering albatross to a laboratory and creating a sound chamber large enough to conduct experimental testing seems unlikely in the near term, but other seabird species can survive in captivity and research could focus on this.
Weather changes caused by climate change and their harmful effects on seabirds, as well as many other plants and animals, are well documented; For example, it makes it difficult for them to find food.
As humans alter ocean habitats, infrasound may help birds adapt by helping them find food even as stocks dwindle. Or human activities, such as more noise, may mask such essential information and have harmful consequences for wildlife. Either way, understanding how and why seabirds use infrasound will help scientists understand its importance in the climate crisis.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Samantha Patrick receives funding from the Human Frontier Science Program