Geese that migrate on high altitude routes over the Himalayas have a lower metabolism and cooler blood when they are flying in low-oxygen conditions
Source:
https://www.newscientist.com/article/2215242-goose-blood-runs-cold-to-carry-more-oxygen-on-high-altitude-flights/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home