Why are some birds louder than other birds?

It's obvious.

• Genetics. Biological differences on average.

Accelerated by:

• Civilizations they're in are allowing them to be without any social repercussions. Blacks increasingly get a "pass" to do any bad behavior they please thanks to top-down elite social conditioning to make people fear being labeled "racist."

That's also the root of differences in other topics like rape and murder rates.