chemscience writes:
TERNS: They cross thousands of miles of open ocean, powered by perhaps an ounce of body fat. If they miss target they die. Who taught terns where Antartica is? Trial & Error would be fatal. One generation of drowned terns and the species becomes extinct.
Trial & error would be fatal? I don't think so. Trial & error
could be fatal , but not necessarily so. Even if most terns drown somewhere along the way, those terns who do make it to Antarctica will be the ones who pass on their navigational skills to their offspring, who will therefore have a better chance of reaching Antarctica when their turn comes. In this way, successive generations of terns will become better and better at navigating the globe on their yearly migration. It's a perfect example of how evolution by natural selection works. No one taught them where Antarctica is, they learned it the hard way.
Anyway, who knows? Maybe there has been a species of migratory birds that has become extinct because none of them could reach their feeding or breeding grounds anymore, for some reason or other. That's also part of evolution: most of the species that evolution came up with in its long history are now extinct. Terns are just lucky it hasn't happened to them (yet).
"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.