When do hummingbirds head south?

Photo by BarrytheBirder

"According to Hummingbird Canada, adult male hummingbirds leave Southern Ontario first in late July with the adult females following next.   Immature hummingbirds are the last to leave in September.   It is rare for hummingbirds to linger in Ontario after the beginning of October".   

But with climate change...?

Please comment if you wish.

BarrytheBirder