Diadem roundleaf bat

The Hipposideros diadema typically lives between four and seven years in the wild, but can live up to twelve years in captivity.

The Hipposideros diadema are usually insectivorous. The diet varies depending on specific location, but they tend to prefer insects such as coleopterans (beetles), lepidoterans (butterflies and moths), and those within the orthopteroid (grasshoppers) orders. However, they will prey on small birds and spiders rarely. Thus, the Hipposideros diadema is sometime classified as an occasional carnivore. These bats are extremely adept predators. By using echolocation, intensified through their highly modified nose and nostrils, they achieve very high rate of success. A constant frequency call is emitted around 50 to 58 kHz, and maintained for 20 to 30 seconds at a time. They are not continuous flight hunters, instead they prefer to take short flights from their perches and intercept the prey in midair. This perch hunting strategy is a low-energy method of acquiring their food. When hunting, they usually fly over a stream or creek that is covered in canopy. They very rarely venture out over open water. Lepidopterans (eared moths) make up a significant portion of their diet and these insects have an auditory range from 20 to 50 kHz. Research has shown that these insects can sense the echolocation pulses and have learned to evade or hide from the attacking bats. Aside from beetles and moths, other insects consumed include weevils and katydids to which the soft parts of such insects are consumed and the inedible parts, such as wings, carapace, and legs are discarded below their perch.

With a heavy body and long, narrow wings, the Hipposideros diadema is adept at fast flight but has relatively poor maneuvering ability. It has adapted to foraging in gaps in forests, such as around tree falls or above rivers. This bat species is not restricted to rain-forest and in outback Australia it forages with eucalypt woodland and open forest, deciduous vine thicket and within towns. Individuals are known to forage up to two and a half kilometers from the roost during the course of the night. During the day it roost in small groups in caves, old mines, sheds, hollow trees and tree branches.