They showed that gps-tracked albatrosses headed towards areas that were predicted (by weather + computer model) to have a lot of infrasound related to strong winds.
The just-so story is that albatrosses benefit from the winds for more efficient flight.
> Infrasound is a form of low-frequency sound that is inaudible to humans but is ubiquitous in the marine environment. Microbaroms are a type of infrasound associated with colliding ocean waves. Such wavy areas are also associated with strong winds, which albatrosses depend on to help them fly efficiently.
I've heard this before and I'm still confused as to an explanation behind something fundamental to localization (how do we know what direction a sound is coming from?)
Humans are quite bad at localizing sound, and it gets worse with lower frequency. But the mechanism is pretty well understood - at a high level, we can only perceive the direction of sound based on the differences measured between our two ears and our brains interpolate direction based on those differences (there's a long discussion of what those differences are and how the geometry of the head and ears affect it, but it doesn't matter).
And it makes sense why it's harder for humans to perceive direction at lower frequencies. If the wavelength is much greater than the distance between our ears then the variation in frequency/phase will be as well. Additionally, the shape of our ears will reflect sound waves differently based on their angle of incidence, but lower frequency sound doesn't reflect off the pinnae - it bends around the head. And at very low frequencies that bending is imperceptible due to the same reason.
So the thing that comes to mind with birds is: how can they localize infrasound with tiny heads? The best explanation I've heard is that as they fly they can sense the change in the infrasound over the area they travel, but that seems really hard to verify experimentally.
What's interesting is that we know human localization isn't time invariant (it's not just based on the sound as it hits your head, but also your head movements in context which can improve localization compared to just keeping still). So it's not implausible that birds do something similar, but it seems to be on much longer time scales.
The other thing to reckon with is we know in humans that sound localization isn't an isolated sense - our brains interpolate direction using all of our senses, including sight (you can localize a sound better by looking at what makes it, or remembering that there was something nearby that could make a sound). Birds can see much better than humans, they can sense EMF, so if they can hear infrasound then we can reason that their brains are interpolating direction based on more than just the sound wave and using it as another input to the system.
It's altogether fascinating. And don't even get people started on acoustic conservation, because we barely consider how the noise we make affects the environment around us.
Of course, birds in flight can't feel the ground vibrate, but I wouldn't immediately eliminate alternatives like infrasound making the birds' feathers vibrate.
I would take this more as infrasound intensity has a minor correlation with directional decisions at best. It certainly could be a valid explanation, but there could be 10 other reasons that just happen to be correlated with sound power.
The birds might just see waves in the distance and head for them... Or be able to see/feel storm weather patterns and know where that means the ideal weather conditions for hunting are.
I'm not sure if that's a viable dismissal, quoting from the paper they looked at travel which was at least 20 km and I'm not sure if albatrosses can reasonably make out visible features of waves at that distance.
> We analyzed the directional preference of wandering albatrosses in relation to available microbarom sound pressure as well as wind speed and direction. This analysis depended on identifying ‘decision points’, points at which the bird decides upon a direction to head in. After splitting GPS tracks into bouts of either directed flight, searching, or resting behavior, we isolated bouts of directed flight exceeding 20 km and extracted the first GPS fix in each bout as the ‘decision point’ (Fig. 1A).
If you did the same study on people, I bet it would give similar results.
But the reality is that peoples travel plans are pretty correlated with the weather - and on a gloomy day they're more likely to just head home and watch TV. Didn't need any infrasound to figure that out!
Irrespective of the ethics of this (if you redirect migration you can kill the population) there's a practical problem which is that high intensity infrasound is quite difficult and expensive to create.
Normally this research works by observing second order effects of known sources of infrasound. For example if we track migration of whales/dolphins in the ocean by tagging them and observe the introduction of some noise pollution (like a new oil well in the Gulf) change those patterns, we can infer that the sound was the source of the change.
A really amazing example of this that someone linked was the pigeon race between Paris and London that was diverted, and the timing of it was directly linked to the Concord going supersonic over the Atlantic on a flight from London to New York (the interesting bit is that the flight was delayed and the timing of the flight lined up perfectly with when the birds were over the English Channel).
The whole field of acoustic/audio conservation is a young one and there's some very interesting research all the time. Off the top of my head, I know NOAA was researching this in the Gulf and South Florida about a decade ago with the University of Miami but I don't know if there were notable publications.
https://www.wnycstudios.org/podcasts/otm/segments/curious-ca...