High altitudes may be a climate refuge for some birds, but not these hummingbirds
Anna’s hummingbirds seem to struggle to hover when there’s less available oxygen
![an Anna's hummingbird flying near a flower](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2022/05/052622_rc_hummingbirds_feat.jpg?fit=1030%2C580&ssl=1)
Anna’s hummingbirds hovering at 3,800 meters above sea level should have been working harder to stay afloat in the thinner air. But their metabolic rate dropped.
Jerome Gaw