how high do hummingbirds normally fly?

Answer 1

Most hummingbirds fly below 500 feet except during migration. When migrating, however, they often do climb to relatively great heights, possibly to avoid dehydration in the warmer air near the ground. Generally long-distance migrants seem to start out at about 5,000 feet and then progressively climb to around 20,000 feet. Just like jet aircraft, the optimum cruise altitude of migrants increases as their "fuel" is used up and their weight declines.

Answer 2

Hummingbirds have laws against flying while high.