(PGP i would assume).
I didn't think of that. Do they overlap in that region?
Just stunning endurance and navigation.
Several days airborne, no food or rest, targeting a spec of land less than a thousand yards wide and less than 10 feet above sea level.
They overlap in the breeding range in Alaska, but not in the wintering range. AGP winters in the Pampas. PGP winters in Asia / Oceania.
So a bird heading from Alaska to NZ is likely a PGP.
Yes indeed, i was thinking about that. It makes me wonder if their evolutionary "strategy" is just to head south into the Pacific, in the knowledge that they will find an atoll within say, 3 - 6 days, where they can refuel for a week or so..? But then again, perhaps not - we know that birds' homing instincts can be amazingly accurate.
You guys are thinking from a grounded POV. Last Friday I was bimbling around Southern England with my brother in a Piper Cherokee at a mere 2,500 feet and we could see from Chichester to Exeter from near Salisbury.
Now tell me about the view from 15,000 feet or more and the eyesight of a bird rather than an aging birder.... migrating birds can scan a huge swathe of ocean and have only to vary their course by a degree or so to head for an island a hundred miles out of their way from the distance they can detect it.
Not to mention that even ancient Polynesian sailors recognised that a line of clouds could mean an island generating them: I'm sure birds learn such tricks as well.
I'm not saying its not remarkable. Just that there is less mystery about it than hairless apes with their ground-bound environment think.
John
Ouch... 3 I don't think I was, but there's room for debate.
Yes its big, but its not infinite and there is room for using normal sensory information to correct navigation errors.
As for the very sensible questions:
Dunno why it changed direction. To take advantage of better winds in a system it could see fairly clearly? To move away from a passing frigatebird? Can't do more than speculate when lacking basic information such as the synoptic charts for the area during the relevant period.
Why didn't it pitch into Hawaii? Because it didn't need to? There's a clear implication there that it knew where it was going, that it was navigating rather than flying blindly in a direction and hoping for a result.
Finally: Yes, or no. Varies between species: may vary between individuals, or why do we get vagrants that sometimes include adults, though most are juveniles? Are all adult vagrants actually previously displaced juveniles persisting in their new environment?
It's fascinating, no argument from me about that. :t:
John
Then there's the apparent round false start along the Aleutian chain before setting off. What's that about?!
All good stuff!
You guys are thinking from a grounded POV. Last Friday I was bimbling around Southern England with my brother in a Piper Cherokee at a mere 2,500 feet and we could see from Chichester to Exeter from near Salisbury.
Now tell me about the view from 15,000 feet or more and the eyesight of a bird rather than an aging birder.... migrating birds can scan a huge swathe of ocean and have only to vary their course by a degree or so to head for an island a hundred miles out of their way from the distance they can detect it.
Not to mention that even ancient Polynesian sailors recognised that a line of clouds could mean an island generating them: I'm sure birds learn such tricks as well.
I'm not saying its not remarkable. Just that there is less mystery about it than hairless apes with their ground-bound environment think.
John