Hammer headed bat, Hypsignathus monstros
(photo by Dr. Bruce J. Hayward, Western New Mexico University)
These fruit eating bats live in central Africa between the east coast and the west coast. As described in Reproductive strategies, they practice Lek behaviour.
They are the largest bats found in Africa, with the males weighing between 228 g up to 450 g. The females are about half that size.
The males gather along a stream and line up on tree branches at 10 m intervals. They then try to attract the females as they pass by using loud vocalizations often referred to as "honking" or "croaking". They will also flap their wings.
(see also web site at Animal Diversity)