Natural selection isn't something that's applied to individual animals, it's something that exerts pressure on whole populations over many generations.

To go with your Arctic tern example, just because one bird can dive deeper doesn't guarantee it's survival. It might still get eaten by a predator or catch a disease or just have a run of bad luck that causes it to starve. However, the birds that can't dive as deeply run the same risks (assuming there's no additional risk to diving deeply) and, over a long time and with a large population of birds, those that can dive deeper will survive to breed more often, until eventually the whole population carries that trait.

You've got it wrong. There is always variation in a population. If a new environmental pressure arrives, some of these variations end up being more successful than others. In some time you might not find any terns who can't dive deeply anymore. There is also a lesson in that that variation is important (for example also in economics, agriculture and so on) - don't bet your countries economic future on just one industry, for example. Evolution theory applies everywhere.

I did not say there is no variation in population. Animals that survive have the ability to survive before environmental pressures. Why ? Yes there are variations among animals, and those that have the trait for survival, survive. The argument is how do these variations that survive get these important trait ? Especially when these traits are specialized to the environment. How do they evolve these specialized traits in time ?

You are only asking for the basics of evolution, every textbook should have you covered (or even Google). And it doesn't happen the way you imagine it, those traits don't have to evolve from one day to the next. Bears can live in Canada because they can hibernate, they didn't live there and had to learn how to hibernate on short notice when winter came.

Have you not read textbook that explained specialized traits as reaction to the environment ? How could that be possible when these traits are needed immediately. You miss the point, why don't we have thousands of animals with the ability to hibernate that don't need them ? Of course traits don't have to evolve rapidly if you already have them or don't need them. But why would you already have the ability to hibernate efficiently if you don't need it ? Why would a bird of prey evolve the ability to hunt from the skies at relative high speed before it can fly ? I'm sorry I read the books there are no legitimate answers. Like said I love science and technology.

> You miss the point, why don't we have thousands of animals with the ability to hibernate that don't need them

Because a tendency to hibernate is likely negative for survivorship when it's not necessary - if lots of other animals are moving around and you aren't, then something is more likely to come and kill you.

On the other hand, lots of animals have other varying traits that aren't obviously useful, but don't exact a significant enough toll to cause them to disappear.

> But why would you already have the ability to hibernate efficiently if you don't need it

Doesn't that assume that bears were transported into Canada and survived because they could hibernate? Isn't it perfectly possible that they moved further north gradually, increasing their tendency to sleep in cold conditions as they did so?

In case of hibernation it seems very plausible that an animal evolved to sleep longer and longer, to preserve energy. I don't understand your problem? It could also work this way: an environment had enough food to sustain 20 bears in winter. If they sleep longer, the environment can sustain 40 bears. If they sleep even more, 100 bears can survive. The population would then grow from year to year, while sleeping more and more. What books on evolution have you read?

I don't think you understand how it works. It's not about animals adapting to survive, but the survival of those best equipped. Not everything survives.

Imagine there's a life and death surprise test on evolution. Demonstrate knowledge and you live. Fail to do so and you die. Part of the population already has a reasonable understanding of it. Others don't. You're looking at it from the perspective of the less knowledgeable cramming their study to pass the test. Evolution in this contrived case can select for those who already happen to understand the topic.

Yes, those best equipped ! But how do you get it equipped ? That's the issue. Yes, not everything survives. But those that survive have all the specialized equipment needed to survive because ?

This is just a very tedious rehash of the very old, already answered, "Eyes need to be perfect to work. So how did eyes evolve?"

> Exactly, survival for most animals are always based on their immediate ability to adapt, not the ability to adapt over thousands of years

Incorrect - it's both. Obviously adaptivity to rapid changes is key, but species don't only disappear/change due to extinction-level immediate events. Individuals also get edged out by their peers (or members of other species) who manage to outcompete them just that little bit for food, or sexual attractiveness, or any of many other reasons.

Natural selection does not occur in a series of instant events! Evolution happens over a long period as the result of a statistical advantage in survival rate. It does not work for rapid change in environment. I don't think anyone is claiming that.