season. The result of this is higher maternal investment per offspring, however the non-monogamous mating system results in low paternal investment. The pups are raised in special sections of the colony’s roosting site dedicated to maternal activities. Other female bats will group at these maternal roosts and aid in the rearing of pups. There are no records of the average lifespan of lesser short-tailed bats. Other bats within the suborder Yangochiroptera have been observed to live for upwards of thirty years, which is unexpected for their small body sizes. During spring/summer, male bats attract a female mate. These pairs will mate during autumn. During autumn and winter, the bats will disperse into smaller colony groups while the female bats are pregnant. Then, when it becomes summer again the bats regroup into a larger colony and the pups are born. Around autumntime, the pups have reached physical maturity. It is unclear at what age they reach sexual maturity. Human impacts and conservation Threats Currently, NZ lesser short-tailed bats are classified as Vulnerable by the IUCN, with the number of individuals observed as declining over time. The introduction of mammalian predators has had a massive impact on the species’ numbers. Since the colonisation of New Zealand and the introduction of three key rat species the endemic bat populations have experienced a reduction in numbers. Polynesian rats (R. exulans) were one of the bat’s main predators up until the 19th century, when the introduction of the black rat (R. rattus) and the brown rat (R. norvegicus) led to heavier predation. Before mammalian predators colonised New Zealand, the lesser short-tailed bat was preyed on by predatory birds, such as the laughing owl. Another common predator of these bats are common house cats, which will catch the bats as they fly out of their roosting sites. The bat roosts are very vulnerable, as they contain more potential prey within a single area. If these roosts were found by a predator, they could experience mass mortality events; in one incident, 102 lesser short-tailed bat deaths were caused by a single house cat in central North Island. Another cause for their decline is increased use of the land for anthropogenic activities, such as logging and agriculture. These activities can often result in negative consequences for the local ecosystem, such as forest fragmentation. For native animals in New Zealand, fragmentation poses threats such as reduced genetic diversity. However,