So Path of the Beast allows a Hunter to chose any non-riding animal from the GMG. The list on pg 126 contains swarms (bats and rats). Can the Hunter chose those? My only issue would be the following:
-Swarms seem stronger than the other animal choices
-From a roleplaying pov its hard to justify a non magic user controlling swarms. I mean a PC is not a vampire or sorcerer or druid that he could mystically command a bat swarm!