Careful of their swarm in Lava caves they will gank you and quickly surround you and push u just little on every hit ... Make sure you have wall behind you and stand with your back against it while fighting them ... Or else Lava ...
I have 8 very high level bats protecting my Dino pen and during an offline raid on me the bats swarmed the three raiders and managed to kill all three of them. The had journeyman Flak and mastercraft weaponry. So in the near future I will be taming many more of them
Bats now deserve some new levels of respect. Like their fellow Cave dweller the Megalania, they have a chance to infect you with Mega Rabies (though only a chance rather the 100% like Megalania)
They are easy to spot and avoid using bug repellent. But due to the new Biological weapon element of them. Engage at a distance where possible. Fight them with sword and pike only as a last resort. Make sure you have a stock of Antidotes or Wyvern Milk before any Splunking