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Variation in winter conditions differentially impacts thermoregulation of endotherms, with some species using torpor as an energy‐saving strategy during periods of negative energy balance. We evaluated how differences in energy balance due to winter ambient temperatures (T_a), would lead to differing torpor expression and roost choice between populations. Here, we monitored T_a and skin temperatures (T_sk) of New Zealand lesser short‐tailed bats (Mystacina tuberculata) using temperature telemetry from an inland population from Pureora, North Island and another from Hauturu/Little Barrier Island (Hauturu), an offshore island. Relative to Pureora, all recorded T_a variables were higher in Hauturu. Hauturu bats used short torpor (<24 h) more frequently (51% of observational days) than their Pureora conspecifics (33%). Furthermore, minimum T_sk of Hauturu bats correlated positively with mean T_a and Hauturu …