Bird- Eating Bats

Dr. Hypercube was kind enough to unearth Darren's old post on bird- eating bats and my additions re New World hoary bats:

"The hoary bat, Lasiurus cinereus, has some very strange "spatial" habits. In the summer, the males live in the southwest, while the females range as far north as the Arctic circle. In the fall the females join them in the southwest, and then they ALL migrate to southern Mexico, Baja California, and South America. I can't think of another animal that does anything remotely like this!
...

"I should add: they apparently mate during the migration. And I wonder: their migration seems to correlate VERY well with that of Nearctic Passerines."

I should add here: we are talking falcon- like on- the- wing predation here. Several tropical genera of bats-- New World false vampires, Old World ghost bats, and more-- kill and eat roosting passerines.