This kind of article is exactly what I think of when I think of great HN articles that are not about hacking or startups. It's just plain interesting for people curious about the world, it doesn't have some kind of political point or message, and it doesn't generate lame discussion.
Yeah pretty amazing article that was surprisingly not just clickbait. Especially this bit:
Frigatebirds are the only seabirds that lack waterproof feathers — if they dive into the ocean or even land on its surface, the water will soak their plumage and prevent them from taking flight again. This should be a death knell to a species that dines exclusively on fish, but it's not. Frigatebirds can soar high above the ocean, eyes peeled for movement in the water below — a sign that a large predator, like tuna or dolphin, is scaring fish to the surface.
And this bit:
It's still not clear how the birds sleep during these epic journeys. Weimerskirch said there's evidence that they can shut down half their brains as they ascend on updrafts.
"They are probably getting small bouts of sleep at this time — maybe two to three minutes," he said.
tl;dr birds have the Uropygial gland which secretes preen oil which most birds then rub over their feathers to keep the water out (the mechanism through which this keeps water out sounds somewhat contested, see wikipedia). The frigate bird has only a vestigial gland for this (sounds like the nature article suggests that the gland shrank due to behavior changes, rather than vice versa. Also sounds like the behavior changes may be due to the prey they feed off of and their habits?)
Wow thanks for trying to find out more about this! This brings me to another question I often thought about: What's the nutritional cost of transforming food into fur or in this case wax...?
I think wax has a pretty simple structure, so probably not very high (but also a fairly high energy content? idek what I'm talking about). Feathers seem like they would be more difficult.
We saw many of these birds and tropicbirds during our Atlantic crossing. They used the trampoline on our catamaran as a rest stop. They also learned that they can't do a carrier landing on solar panels. It was funny to watch them come in for a landing and slide right off the back of the boat.
It looks like they feed on flying fish, primarily. These would jump out of the water and skim across the surface for hundreds of meters, and then BAM!, a bird would swoop in and end its existence.
I've woken up to screaming crew members finding a new winged, scaly bedmate in the morning as well. Some captains loathe them since they can cause a mess and a stink if they fail to clean all of them up and let them linger for a day in the hot sun.
I'm working on getting the rest of the photos and videos. I've basically been in land mode for the past month: visiting family we haven't seen in over a year, job hunting, boat maintenance. And we're trying to get settled but haven't gotten really comfortable at being landlubbers.
We've gone a bit overboard and have "smarty" boat the traditional sailors loathe. Solar and battery monitors are wired into a Raspberry Pi for logging and graphing. I'm currently using Signal-K [0] as an instruments data server.
You may be also interested in my friends project called Boat Remote [1]. They can control the electrics and display data on a Pebble watch.
"Allowing air currents to do the work of lifting them makes frigatebirds' flight hugely efficient. The heart rate monitors Weimerskirch and his colleagues attached to the birds showed that they didn't flap their wings at all while gaining altitude — the energy costs of ascending thousands of feet in the air were the same as when they were sitting still."
Aeronautical engineers: what's it take to develop long-range flight vehicles that are this efficient? Graphite wings/fuselage?
This was exactly my research in gradschool. Sorry to self promote, but it's not often I get a chance to discuss my incredibly esoteric dissertation topic. I was part of a team working to get a UAV to perform a dynamic soaring maneuver, which allows an aircraft (or bird) to extract energy from wind gradients to support flight [1].
DS was first recognized in the albatross by Lord Rayleigh. Like the frigate bird in this artcle, the albatross is able to expend very little enegery while traveling great distances, thanks to its oceanic environment. Close to the ocean surface, friction between the wind and the water causes windspeed to slow. As you move up in altitude, windspeed increases. So you have this nice gradient that is always there for the albatross to take advantage of. The albatross locks its wings into place (using a big tendon sheath), and it performs successive climbing/diving maneuvers through this gradient, netting it kinetic energy at the end of each cycle.
So my role in the project was the brains behind a soaring aircraft, which was being developed in tandem. I'm a little fuzzier on the specifics of how the aicraft was made, but it was a novel manufacturing process that allowed us to build very large, seamless carbon fiber wings [2].
As part of my work, I had to figure out how to find trajectories that would support flight, given an aircraft. I also had a formulation that would find an optimal aircraft as part of the solution. The key takeaways for the aircraft are very large wingspan, and also some heft to the airframe; you don't want the aircraft being too light, because most of the energy gain comes during the transfer between potential -> kinetic energy during the dive phase of the maneuver.
Anyway, anyone really interested in the topic can take a look at our publications [3]. We looked at soaring in the jetstream, soaring in hurricanes, even reinforcement learning for a UAV to figure out how to soar better.
Gliders have existed for many years, and sometimes skilled pilots can fly for hundreds of miles riding thermals and updrafts. The problems are payload and reliability. The aircraft itself may not weigh much, but whatever you want to carry will likely be. And if you can't find a thermal when or where you need one, you have to land.
If birds can maneuver continuously for over two months without landing, so can a machine. For me the question is can we both design the vehicle to have the correct physical properties, and an intelligent-enough automated flight computer? I think the former will simply require a very very large wingspan made of the lightest strongest material we have [currently Carbyne, formerly Graphite, with the metal alternative being "New Magnesium"].
Once this is accomplished, we could potentially make air transportation [in certain routes] much cheaper. This would have benefits like eliminating the risk of ocean pollution when a large ship crashes/capsizes, faster transportation of goods, and at the same time not be limited in transportation cost by oil market prices. And such designs, if made practical, could possibly be transferred to new aerospace engineering where weight-to-strength are at a premium.
Designing an intelligent flight computer that can account for air currents could also make flight less turbulent, and potentially improve our understanding and prediction of weather patterns.
we've developed robots that will 'collect' biological matter (slugs) and ferment it into gases which can be used for electrical generation, but it's incredibly inefficient and likely not suited for aviation.
> A prototype robot capable of hunting down over 100 slugs an hour and using their rotting bodies to generate electricity is being developed by engineers at the University of West England's Intelligent Autonomous Systems Laboratory.
Glider pilots have told me about using the heated air up drafts caused by large mall parking lots as a way to stay elevated. Amazing to think of all the air that is moving around us, and then using it to "bounce" from current to current.
Thanks. A roofing contractor told me once that putting a white reflective coating on flat roofs instead of the usual black tar would reduce the A/C bill by about 15%.
Maybe unmanned drone gliders without any cargo, just some sensors.
Of course, if they're anything like the frigate birds themselves, one of these gliders will eventually collide with a frigate bird.
Then what?
On second thought, just put sensors on some frigate birds and collect the data later, as this scientist is already doing. Sell the data to Google Earth. Split the profits with the birds.
This probably works because the frigate bird is so light compared to an aircraft: thermals generate sufficient lift for them to stay aloft. Though you might be able to apply some of this to a really light UAV...
Fascinating. This bit is troubling though "A follow-up study with miniature loggers that monitor sleep will test this hypothesis". How would such a logger unobtrusively monitor sleep?
Surprisingly, yes; there is a device named "Neurologger 2/2A[0]" which has a mass of just over 2g and a battery life of 33 hours.
From the abstract of "Do birds sleep in flight?", Niels Rattenborg[1]:-
"The recent miniaturization of EEG recording devices now makes it possible to measure brain activity in flight. Determining if and how birds sleep in flight will contribute to our understanding of a largely unexplored aspect of avian behavior and may also provide insight into the function of sleep."
and in the section entitled "Future Directions":-
"Until recently, EEG recording devices were too large for a bird to carry in flight. However, Vyssotski et al. (2006)[2] recently developed and successfully deployed an EEG and a global positioning system (GPS) logger on pigeons during short, daytime homing flights to their loft."
I thought they were mainly thieves. When I was in Galapagos, I was actually taking pics of a booby feeding its kid when a frigate flew right through both of them, grabbing the fish as it flew through. All three of us were surprised.
They also bother the other birds in mid flight, causing them to drop their food.
