by Animals cover great distances in search of food. While caribou, reindeer and wolves put up considerable mileage on land, seabirds are unrivaled in their distance of travel. Arctic terns travel from the Arctic to Antarctica and back as part of their annual migration. Wandering Albatross (Exulans Diomedea) to fly the equivalent of ten times to the Moon and back over her lifetime.
Much research has been done on how seabirds choose their flight paths and find food. They appear to use their sight or smell to assess local conditions.
However, wandering albatross can travel more than 10,000km in a single foraging trip, and we know little about how these birds use medium- and long-range cues from their environment to decide where to go. .
However, for the first time, a recent study by my team provides insight into how birds such as wandering albatross can use sound to determine what conditions are further away.
How seabirds use low frequency sound
Previous research has shown that seabirds seek information not only about where to find food, but how to do so efficiently. We found that the way wandering albatrosses use their sense of sound may be crucial.
Our study looked at how these birds respond to a type of very low-frequency 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 crash together or against coastlines, they create an infrasound frequency known as microbursts. This was 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 could provide information about where these areas are, and alert birds to good foraging patches.
Efficient hunting is particularly important for large seabird species such as the wandering albatross, which has a wingspan of 3.5 metres. Their size means they rely on the wind to take off and fly effectively, unlike small birds like puffins, which flap their wings up to 400 times a minute.
High wave activity also indicates strong winds. Since we know that wandering albatross rely on wind to fly effectively, my team’s study suggests that infrasound could give them a long-range clue as to the best foraging conditions.
Infrasound is also generated when waves crash against the coast, and we know that many seabirds use the coastline to choose their flight paths and find their way back to their breeding colonies. Thus, infrasound could reveal the location of static features such as coastlines, providing important information for seabirds over long distances.
Despite the potential of this cue for seabirds, our paper (published in PNAS) is the first evidence that seabirds may respond to infrasound, which is monitored globally through a network of sensors installed by the Intergovernmental Panel on Nuclear Test Ban (CTBTO). .
This system was installed to detect nuclear tests, but the amount of data scientists can use is huge. We combined the CTBTO records with our own GPS tracking data from 89 wandering albatrosses to compare the birds’ microbrows and movements.
What we learned
This allowed us to isolate data that showed how these albatross were making decisions about where to go next. Our results showed that they chose the direction with the highest infrasound. This suggests that the birds may use infrasound to find food or to minimize the energy they use while traveling. However, we cannot say for sure why higher areas are better.
Our findings may also give scientists insight 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 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, but no tests have been done on seabirds.
It is unlikely in the short term that wandering albatross will be brought into a laboratory and a sound chamber large enough to run experimental tests will be created, but other seabird species can survive in captivity and research could focus on this.
The changes in weather driven by climate change, and the detrimental effects these have on seabirds as well as many other plants and animals, are well documented – making it harder for them to find food, for example .
As humans alter ocean habitats, infrasound may help birds adapt by helping them find food, even as stocks decline. Or human activity, such as more noise, could mask this kind of essential information, with adverse consequences for wildlife. Either way, understanding how and why seabirds use infrasound will help scientists understand its importance in the climate crisis.
This article from The Conversation is republished under a Creative Commons license. Read the original article.
Samantha Patrick receives funding from the Human Frontier Science Programme
