2400000000 / 58000000 ~ 41. 234000 / 70000 ~ 3. If we talking about preserving birds I would still address the cat issue before the wind turbine issue.

Also there is a chance that birds killed by cats windturbines were already weak and soon to die.

Don't take the above sentence seriously. It's just to show that arguments that seem nice might not hold their value at second glance.