No deep mystery here. Those that don't make it to the sea (along with 99% of their siblings) do not live to reproduce.
Mother nature can be a relentlessly cruel and heartless educator but no PhD required to crawl down the beach.
Just getting
Mib’s post to
appear. Latest posts told me he’d written it 167
minutes before I arrived. I wish the powers that be would sort this problem.
Corby - // In some bird species, the ability to migrate successfully is innate.
That shows there is no exchange of information from one to another. //
No it doesn't show that - it shows that there is no exchange of information that we can recognise, which is not the same as no exchange of information.
It shows newborns were created with the instinct already part of them. It's debatable whether that counts as an exchange when it was there as a consequence of their creation.