Near the start of Batman Begins young Bruce Wayne falls down a well and gets attacked by bats. Later we meet the bats again when he first discovers the bat cave and in one scene Batman uses the bats to destroy a Swat team. Is there any evidence of what type of bat they are in-universe. Does the habitat or extremely strong swarming and mobbing response to humans suggest what species they might be?
American Brown Bats
The vast caverns had once been used to shelter runaway slaves escaping to the North. Damp limestone walls glistened beneath the subdued interior lighting that Bruce had installed years ago. A shallow, slow-moving river was all that remained of the underground waterway that had carved out the caverns in ages past. Massive wooden arches, high overhead, helped to support the mansion’s foundations.
Scores of North American brown bats roosted amidst the jagged stalactites hanging from the ceiling. Towering calcite columns rose hundreds of feet in height. The bats squeaked and rustled overhead.
This tallies nicely with what we know from other sources, notably the DC Visual Dictionary
"though the scores of American Brown Bats (Myotis lucifugus) perched high above the Batcave floor were a nuisance to Alfred's fastidious cleaning...""