No idea what this has to do with aviation rumors or news but I think migratory birds like geese go +20,000 feet. Just did a quick internet search and found the following.
The Bar-headed Goose is one of the world's highest flying birds, having been seen at up to 10,175 m (33,382 feet). It has a slightly larger wing area for its weight than other geese and it is believed this helps the goose to fly high.
[2] Studies have found that they breathe more efficiently under low oxygen conditions and are able to reduce heat loss.
[3] The
haemoglobin of their blood has a higher oxygen affinity than that of other geese.
[4] The Bar-headed Goose
migrates over the
Himalayas to spend the winter in
India,
Assam, Northern
Burma and the wetlands of
Pakistan. It migrates up to Koonthankulam of Tirunelveli district, Tamil Nadu in the southern part of India
[5]. The winter habitat of the Bar-headed Goose is on cultivation where it feeds on barley, rice and wheat, and may damage crops. The bird can fly the 1000-mile migration route in just one day as it is able to fly in
jet stream.
Bar-headed Goose - Wikipedia, the free encyclopedia