mostly based on observations of stories of other birds in similar situations.
basically a bird should not be so defenseless and should certainly not let a human pick them up etc if they are wild.
http://philadelphia.cbslocal.com/2017/04/19/expert-video-of-woodpecker-hitching-ride-through-chicago-tells-only-part-of-story/
https://www.mnn.com/earth-matters/animals/stories/cab-driver-and-hawk-become-buds-during-hurricane-harvey
mostly based on observations of stories of other birds in similar situations.
basically a bird should not be so defenseless and should certainly not let a human pick them up etc if they are wild.
http://philadelphia.cbslocal.com/2017/04/19/expert-video-of-woodpecker-hitching-ride-through-chicago-tells-only-part-of-story/
https://www.mnn.com/earth-matters/animals/stories/cab-driver-and-hawk-become-buds-during-hurricane-harvey