If you zoom-out a ship is just a small island, a rock or something floating around in the water that can be used as a pit-stop. If birds evolved to judge something as useful to rest - these birds just see a higher quantity of pit stops. Would be interesting if they lower the required calories to make the trip beforehand as time passes.
Container ships steam at ~20 kts. If they need to get somewhere and are picking these pit-stops at random as if they are stationary, about half the time it would be a rather maladaptive choice.
My dad used to work on oil carriers in the North Sea, he said an owl had stowed away and nested on one of bouys near a field. The place was covered with skeletons of birds
Presumably the owl ate them. Owls swallow their prey whole, so the skeleton comes out intact. Dissecting "owl pellets" as they are called, and trying to piece together the skeleton within is a popular educational youth activity.
For those wondering, some of these birds can fly over 5 miles high. From 5 miles above sea level, the distance to horizon is 200 miles. From 5 miles high, you could see the tip of mount Everest above the horizon from 410 miles. Great snipes can fly thousands of miles in one continuous 60-90 hour flight.
> One of the great snipes stayed above 8,000 meters (4.97 miles) for more than five hours one day, rising to a maximum altitude of around 8,700 meters (5.41 miles). This is the highest altitude ever recorded for an identified migratory bird.
At 8km high it's easier to believe that they'd see ~660km away (410mi), although I don't know if weather, pollution or some distortions get in the way.
I wonder if, even if the bird doesn't take the boat for a long distance (i.e. cutting off time spent flapping), just having the ability to rest and recover in the middle of the ocean provides it the boost to keep on going. Or some safety factor. Just like Midway Atoll for us...hah.
This is the amazing evolutionary advantage of albatrosses; they fly using a technique called dynamic soaring, which allows them to extract kinetic energy from the wind. It's the same concept really as moving sidewalks in the airport, so their gliding heartrate is about the same as when they're resting on the beach or water. This is what allows them to fly such massive distances across the ocean!
> Where's the gradient? Do they fly at the boundary between different wind speeds?
At the surface of the water, windspeed is lower than at higher altitudes, so that's where the gradient is. If you watch an albatross soaring over water, you'll watch it dive so low its wingtip touches the water surface, and then it'll climb in altitude, before turning to dive again. Here's a good diagram of the whole process: https://www.researchgate.net/profile/Sameh-Eisa/publication/...
Rats also travel by ships, reaching islands where they have not been before. I think even the old Romans mentioned cats traveling on their ships. Not to mention the various pathogens that traveled with the people on ocean crossing ships, causing severe epidemics among natives not used to such.
We've been sailing around the world for 500+/- years now. Moreso in the past than we used to. Presumably the consequences have already shown themselves.
It also seems likely that navigation is much more standardized. Ships follow more regular paths, so it may be easier to jump from ship to ship (at least compared to the 1700s or earlier).
