I measured nocturnal activity of 37 New Zealand long-tailed bats (Chalinolobus tuberculatus) during pregnancy, lactation, and postlactation. Availability of flying insects peaked during lactation. C. tuberculatus was active throughout the night, making 4.0 ± 0.2 SE foraging bouts interspersed with roosting periods. Bats were active for 71.3 ± 1.6% of the night (354 ± 10.6 min). The first foraging bout was significantly longer than later bouts, but length of roosting bouts did not vary. Bats returned to the vicinity of their day colonies to roost at night. Ambient air temperature (3–21°C) had little influence on duration of activity. Length of active periods did not differ among reproductive females, nonreproductive females, and adult males. Reproductive females were active for significantly longer periods during lactation than during pregnancy, but not after lactation. I predict few differences between reproductive classes because energy demands are high throughout the reproductive cycle, females have different mechanisms (such as increasing foraging efficiency, using torpor, and selecting thermally beneficial roosts) for balancing high energy requirements, and energy demands limit all classes in a cold temperate climate when food is in short supply.