I was surprised that some birds can fly even higher. There is a record of Rüppell's vulture at 11+ kilometers altitude.
Sadly this wonder of nature was deduced from the 5 feathers that were all that remained after the noble creature was ingested by a turbofan engine of an airliner.
https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=7...
Yeah, unfortunately.