Just imagine suggesting that ISO 10,000 images might be acceptable a decade ago - we'd have been laughed out of the room. Your images really do look very nice, but I have shot enough wildlife back in the shadows to have an idea what the exposures were like, back there.
I learned much of my bird shooting from Harry Behret - who said he ALWAYS shot birds at 100 ISO. It took me a trip to Florida to realize he was shooting white birds in direct tropical sunlight. I suggested he try shooting deer in deep shade 30 minutes before sunrise to see how the other half lived. 😄