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Autumn‐winter energetics of Holarctic tree squirrels:a review
Author(s) -
REYNOLDS JONATHAN C.
Publication year - 1985
Publication title -
mammal review
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.574
H-Index - 76
eISSN - 1365-2907
pISSN - 0305-1838
DOI - 10.1111/j.1365-2907.1985.tb00395.x
Subject(s) - holarctic , energetics , basal metabolic rate , ecology , biology , energy expenditure , homeothermy , thermoregulation , biochemistry , genus , endocrinology
Similarities in general size, geometry, lifestyle, and environment mean that certain energetic constraints are common and peculiar to Holarctic tree squirrels as a group. Holarctic tree squirrels are relatively small, diurnal mammals which, in association with their food niche, maintain activity throughout the autumn‐winter period. Despite this, they exhibit no major morphological or physiological adaptations to minimize energy expenditure at low temperatures; on the contrary, both basal metabolism and conductance are higher than expected on the grounds of physical size. When they are active energy expenditure is therefore strongly influenced by effective ambient temperature for these species when active in their natural autumn‐winter environments. Nest use allows near‐basal metabolism at most natural ambient temperatures. The balance of economical inactivity against feeding rewards offset by cold exposure must therefore be a crucial aspect of the lifestyle of these squirrels.