OWN- Apologies for the late reply I have been trying to find a fairly lengthy response to a similar question to yours which I was asked just the other day, managed to come across it a few minutes ago
"It's rather tough, especially in Kruger where one is not able to handle the animals unless it is for an approved SANParks endorsed research project. One also needs permits in the majority of our provinces in order to capture and handle bats. However this does not mean you still cant look around and search for these little guys.
One should always look for simple yet easily over looked signs which will lead you to the presence of bats being in the area. These include white urine stains on the sides of houses and bungalows, brown semi circular oil marks surrounding a small crevice/hole, droppings at the base of the roost, sounds (ie. audible squeaks such as the high level bridges in Kruger), and smell (Free Tailed Bats especially, emit a pungent smell when roosting together in large colonies).
At first it's extremely tough searching for bats and often people will try it once or twice and get rather despondent because they have not found any, but one must persevere. Slowly but surely as you start reading up on the species and familiarizing yourself with where a particular species would prefer to roost your areas that you check out start to change. For example if one were to look for roosting Horseshoe Bats, a cave dwelling species, one would not look in a bungalow but instead in hollow trees with a fairly large trunk.
The easiest places to find bats within Kruger are on the sides of the Lala Palms, under the leaves of Lala Palms, under the thatch over hangs, in the thatch itself where the bricks, poles and thatch meet, hollow trees (be careful of snakes and scorpions) and even under safari tents. The lekker thing about Kruger is that bats will utilize almost any man made construction as a roost so one does not always have to look in places such as trees and so on although this is still advisable.
One would also need to know what species would roost where so whether a species is a crevice dweller or a cave dweller, a free hanging rooster or one which will roost under bark. This will help you be able to target different species. So lets say I was aiming to find Free Tailed Bats: I would immedialty go look in the thatched accommodation and the expansion joints of the high level bridges as they are crevice dwellers whereas if i was searching for Epauletted Fruit Bats I would look in the Lala Palms or trees with sufficient foliage cover surrounding the fruit trees.
Hope this helps a little bit?