Animals cover amazing distances when they are looking for food. While caribou, reindeer and wolves clock impressive mileage on land, seabirds are unmatched in their distance travel.
Arctic terns travel from the Arctic to Antarctica and back as part of their annual migration. Wandering albatrosses (Diomedea exulans) will fly the equivalent of ten times to the Moon and back in their lifetime.
There is a lot of research on how seabirds choose their flight paths and find food. They seem to use their sight or smell to assess local conditions.
Wandering albatrosses can travel more than 10,000km on a foraging trip, however, and we don’t know much about how these birds use medium- and long-range cues from their environment to make decisions. where to go.
For the first time, however, my team’s recent study provides insight into how birds such as wandering albatrosses can use sound to determine conditions at a distance.
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How seabirds use low frequency sound
Previous research has shown that seabirds not only seek information about where to find food, but also how to do it efficiently. We discovered that the way wandering albatrosses use their sense of sound can be important.
Our study looked at how these birds respond to a very low-frequency type of sound called infrasound, which can travel thousands of kilometers.
Although it is usually inaudible to humans, we know that some animals can hear infrasound. When waves collide or collide with beaches, they create an infrasound frequency called microbarums. This is the type of infrasound that our study looked at.
We know that areas of high wave activity can be associated with upwellings where fish are brought to the surface. Infrasound can provide information on where these areas are, and inform the birds of good search patches.
Efficient foraging is especially important for large seabird species such as the wandering albatross, which has a wingspan of 3.5 meters. Their size means they rely on the wind to take off and fly efficiently, unlike smaller birds like puffins, which flap their wings up to 400 times per minute.
High wave activity also indicates strong winds. Since we know that wandering albatrosses depend on the wind to fly efficiently, my team’s study suggests that infrasound can give them a high degree of where the best search conditions are.
Infrasound is also produced when waves hit beaches, and we know that many shorebirds use the beach to choose their flight paths and find their way back to their breeding colonies. Therefore, 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 PNAS) is the first evidence that seabirds can respond to infrasound, which is monitored worldwide through a network of sensors. which was placed in the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) .
This system was installed to detect nuclear tests, but its byproduct is a lot of data available to scientists. We combined the CTBTO records with our own GPS tracking data from 89 wandering albatrosses to compare the microbarum and the birds’ movements.
What we learned
This allowed us to isolate data that showed how these albatrosses appeared to make decisions about where to go next. Our findings show that they choose the direction with the strongest infrasound.
This suggests that birds may use infrasound to find food or to reduce the energy they use during their travels. However, we cannot say for sure why stronger areas are better.
Our findings may also give scientists insights into how other birds make decisions on medium and long-distance journeys.
Like many studies that test a hypothesis for the first time, my team’s study raises many questions that 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, but there have been no tests on seabirds.
Getting a wandering albatross into a lab and building a sound chamber big enough to run experimental tests on seems unlikely in the near term, but other seabird species can survive in captivity and research can focus on this.
The changes in weather due to climate change, and its detrimental effects on seabirds as well as many other plants and animals, are well documented making it difficult for them to find food, for example.
As humans alter ocean habitats, infrasound may help birds adapt by helping them find food, even if stocks dwindle. Or human activity, such as a lot of noise, can mask this kind of important information, with disastrous consequences for wildlife.
Either way, understanding how and why seabirds use infrasound can help scientists understand its importance in the climate crisis.
Samantha Patrick, Reader in Marine Biology, University of Liverpool
This article is reprinted from The Conversation under a Creative Commons license. Read the original article.
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