I came across a fascinating story about a tiny bird that puts human endurance records to shame. It was a about a small songbird called the blackpoll warbler that every autumn makes a non-stop flight from Vermont to Puerto Rico, a distance of 1between 1,400-1,700 miles that takes it three days to complete. This is a a pretty amazing feat for a bird that weighs just 12 grams.
By putting tiny locator devices on the birds, researchers were able to track their paths. The flight in entirely over water which means that the bird cannot rest at all and only half of them survive the journey. How do they do it?
To prepare for the migration blackpolls gorge themselves on insects and can double their body mass pre-trip. The added bulk gives them the energy to fly over open water without stopping, because coming to rest in the Atlantic Ocean would be certain death for a blackpoll.
Blackpolls aren’t the only birds with an epic migration route. Albatrosses, sandpipers and gulls all travel long distances to southern wintering grounds, but these birds take a longer route that takes them over land. So why do blackpolls take such a risky route? Scientists aren’t quite sure. Perhaps, the authors say, blackpolls just want to get the migration over as soon as possible, since it is the most dangerous activity they partake in.
This shows how species can spread to distant places even though it seems unlikely to us because of the huge geographical barriers they need to cross. Furthermore, they can carry seeds within them that can grow in the new locations too.
The paper can be read here.
I don’t buy it. I’m not saying problem solving and conscious choice are exclusively of the higher primates, or dolphins, or elephants (mammals). Crows show amazing problem solving skills. I just don’t see a bunch of birds swapping notes and deciding that the ocean crossing version of the migration is better, all things considered, than land crossing version.
I’d suspect that over time evolution favoured the members of the species that for reasons we can’t replay or know ended up being ocean going. But I don’t think they wanted the migration over as soon as possible to avoid danger and so chose and ocean route.
Of course, this could be a science writers teleological interpretation of what the report said…
Arctic Terns breed in the Arctic and “winter” in the Antarctic. Minimum distance 19,000 km. Average annual migration, per Wikipedia, is 71,000 to 90,000 km. Evolution is awesome.
http://en.wikipedia.org/wiki/Arctic_tern
It makes me wonder if the birds evolved at a time when the distance was much shorter. Evolution comes in gradual increments, and so does the distance. The Atlantic Ocean has widened gradually for 150 million years at a few centimetres per year. The birds may have not been around that long, but did they start when the distance was much shorter, or did they begin when it was already near the width it is now?
@3 The Atlantic Ocean is widening at the mid-Atlantic Ridge. Just as North America is, Puerto Rico is well west of the mid-Atlantic Ridge spreading zone. So the widening of the Atlantic Ocean has not affected the travel distance of the migration route of the Blackpoll Warbler.
But Puerto Rico lies on the Caribbean Plate, not the North American Plate on which Vermont and the rest of the continental US lies. The Caribbean Plate is moving eastward compared to the westward movement of the North American Plate, making the distance between Vermont and Puerto Rico longer. At about 3 cm/year relative movement between the plates, in one hundred thousand years (time enough for speciation) Puerto Rico has moved about 3 km further east. As that is the short end of a very long triangle, the migration travel distance has changed only negligibly due to plate movements in the last 100,000 years.
Umm, Mano, those authors need to learn a bit of ornithology. They seem spot on about the warblers — those guys can’t swim, so the route they follow has to be non-stop. But the other three groups they mentioned — albatrosses, gulls, shorebirds — not only fly long distances over water, but are perfectly capable of landing on the water and then taking off again. Gulls frequently feed at sea, and albatrosses only touch land in order to nest.
Other warblers, tanagers, grosbeaks, etc. do follow mostly land-based routes, although a surprising number of them cross the Gulf of Mexico from the Yucatan to Louisiana and back every year. (Ruby-throated Hummingbirds are notorious for this, seeing how small they are and how high their metabolism runs as a result.)
psweet --
Ornithology is for the birds.