Body Temperature in the White-Footed Mouse, Peromyscus leucopus noveboracensis

Thermal Physiology and Energetics of Peromyscus; Ontogeny, Body Temperature, Metabolism, Insulation, and Microclimatology

“…;Morrison and Ryser, 1959;McNab and Morrison, 1963;Sacher and Duffy, 1978) but might be expected to lower Tb at low TaS(Hart, 1971).As a generalization, when Ta is within a middle-range of about 10-30?C, all species of Peromyscus can maintain consistent core Tbs despite variations in Ta; further, interspecific differences in the Tbs maintained at such mid-range Tas are at most subtle, especially in view of methodological differences from one investigation to another (McNab andMorrison, 1963;Musser and Shoemaker, 1965;Hill, 1975b). Among rodents generally, desert and warm-climate forms have Tbs about 1?C lower than nondesert forms at moderate Tas(Hart, 1971); within Peromyscus, P. crinitus adheres to this pattern (McNab andMorrison, 1963).…”

“…potential determinants of Tb include sex and time of year(Morrison and Ryser, 1959;Hock and Roberts, 1966;Roberts et al, 1966;Riedel, 1967; Smith and Criss, 1967;Lynch et al, 1980b). Additionally, at least in P. leucopus and polionotus, particular individuals consistently tend to maintain relatively high, or low, Tbs in comparison with other individuals(Morrison and Ryser, 1959; Smith and Criss, 1967;Hill, 1977). Ionizing radiation can alter Tb as well as metabolic rate and thermal conductance (Braham andSacher, 1978).…”

“…Ambient humidity (ca. By this standard, circadian rhythmicity of Tb has been established only in P. polionotus and leucopus(Smith and Criss, 1967; Lynch, Bunin, and Schneider, 1980), although daily cycling of Tb in the presence of light-dark cycling has also been reported(Kendeigh, 1945;Morrison and Ryser, 1959; Andrews, 1978;Sacher and Duffy, 1978; Vogt and Lynch, 1982). In P. leucopus at Ta = 29?C, neither average Tb nor variation in Tb changes with age(Sacher and Duffy, 1978).The question of whether Peromyscus exhibit true circadian (endogenous) rhythms of Tb can be resolved only if animals are examined while lacking exogenous cues as to the time of day, that is, under constant conditions of Ta and light or dark.…”

The effect of constant light and dark on the circadian nature of daily torpor inPeromyscus Leucopus

“…First, the daily decrease in body temperature may be directly influencing the period of the free-running rhythm, or secondly, a common mechanism may influence both the extent of torpor and advance of the torpor rhythm. Distinction of these alternatives should be possible by employing induced hypothermia, as has been reported previously for this species (Morrison and Ryser, 1959). Examination of the shifts in other circadian rhythms, relative to the extent of daily torpor, also seems warranted.…”

“…Other parameters could not be determined because body temperature in nontorpid mice fluctuates considerably in this species as reported previously (Morrison and Ryser, 1959).…”