Hummingbird cross Bering Strait
The ruby-throated hummingbird flies 500 miles nonstop across the Gulf of Mexico during both its spring and fall migrations

The Bering Strait is about 82 kilometres (51 mi) wide at its narrowest point, between Cape Dezhnev, Chukchi Peninsula, Russia

Based on the two facts above, it appears possible for a humming bird species to cross the Bering Straits if the weather becomes suitable to survival. Who would have thought? 

That said, I am not sure how a humming bird who know which direction to fly in to make a successful crossing.