From all I have read by people who should know, the relationship between birds and humans has been complex and significant for many thousands of years. Birds will even cuddle close to us.
Supposedly, the closeness displays the bird's faith in you, and they may shake their tailfeathers as a sign of affection. Falling asleep on your arm can mean they have trust in you.
I became curious about the subject because of Jeanetta's repeated inexplicable experiences with wild birds.
The first came a while back when a sparrow found its way inside the house. After it fluttered wildly about, it finally landed, seemingly exhausted, on top of a bedroom door. At that point, rather than reaching for a fishing net, sheet, or towel to capture the terrified little bird, she slowly approached and held out both hands. The bird surprisingly hopped into her open palm, which she gently closed, carrying the bird to the door to release it back into the wild.
The second time, she happened across a bird sitting in the street and eased up to it, knelt and extended her open hand, which the bird accepted. She carried it off the street and set it free. Passing the spot a while later, the bird was nowhere to be found.
A third instance happened just the other day on our rear deck as she was refilling a water fountain for some thirsty........