Occurence and rate of shivering were measured to assess thermoregulatory responses of captive moose (Alces alces) infested with winter ticks (Dermacentor albipictus). Shivering was observed on 47 occasions in 5 of 8 infested moose calves from October to April; in contrast, 4 moose calves not infested with winter ticks did not shiver under identical weather conditions. Only 5 shivering bouts occurred from October to March, all on a single day. The other 42 shivering bouts occurred in April with bouts lasting 1–103 min. During the April bouts, ambient temperature was 1– 4 °C (42 of 42), maximum wind speed was ≤12 km/h (38 of 42), and it was raining (30 of 42). Shivering was associated with 23–44% hair loss in April, but not during cold weather in mid-winter despite 5–10% hair loss in March. Maintaining stable core body temperature during late winter-early spring could compromise the energetic balance of wild free-ranging moose with extensive hair loss and abundant ticks, in conditions equivalent to or worse than measured in this study
