I agree with you in that correlation is not causation but I think you're overcomplicating things a bit in your example; birds don't have a healthcare system, th

I agree with you in that correlation is not causation but I think you're overcomplicating things a bit in your example; birds don't have a healthcare system, they're either completely healthy and fit or get killed by a predator or by their inability to migrate or some other external factor relatively quickly.