Metabolism and energy budget in the snow vole

Abstract

The average daily metabolic rate (ADM'R), resting metabolic rate (RMR), rhythm and sum of daily activity, as well as consumption and food utilization were investigated in the snow vole, Microtus nivalis (N=46), captured in Tatra Mountains (1400 to 1480 m above sea level). The ADMR of M. nivalis at 15°C amounts to 3.82. and at 20°C to 3.56 cc 0,/g. hr. The relationship between ADMR and body weight is described by the equations: for 15°C ADMR cc O 0 /g hr=8.58 W-°-237 , and at 20°C ADMR cc 0,/g h=8.75 W-°- 284 The thermoneutral zone for snow vole is around 20°C. At this temperature RMR is equal to 6.33 kcal/kg°-75 hr, and increases by 113.9% at -10°C. The efficiency of thermoregulation in this range amounts to 3.8°/o/°C. The temperature of vole's body depends to some extend on ambient temperature: in the range of 10 to 20°C it is constant and equal to 38.1°C but falls to 32.7 at -5°C. The sum of daily activity amounts to 8.9 hours. The rhythm of activity shows a biphasic 29.25 kcal in the form of dried fruits of Vaccinium myrtillus; consumption of leaved stems is higher by 22.7%>. The daily energy budget (DEB) calculated for summer and winter is almost identical and amounts to: DEB (kcal/g day) = 1.25 W-°- 264 . During a day the vole weighing 33 g dissipates 16.4 kcal, or 0.497 kcal/g, on the average.

Levels of social tolerance between snow volesChionomys nivalis during over-wintering periods

“…Additionally, C. nivalis predominantly uses the cavernicolous microhabitats created by permanent rocky formations throughout the year and it may benefit from the stable, mainly stenothermic, microclimatic conditions of such structures (Kryštufek and Kovaciè 1989). This idea is congruent with the fact that snow voles, apart from having good insulatory properties, manifest almost identical energy budgets for winter and summer (Bieñkowski and Marsza³ek 1974).…”

“…Vole species that become social during winter typically exploit foods that do not impose relevant constraints in terms of quality, quantity or renewal rate (West andDublin 1984, Wolff 1984). However, in the case of the C. nivalis, the associated costs of local trophic restrictions in the alpine zone (Bieñkowski and Marsza³ek 1974) could modulate the type of social strategy adopted (Ostfeld 1985b). Indeed, snow voles present much better insulatory properties than other microtines from lower altitudes as the bank vole Clethrionomys glareolus or the common vole Microtus arvalis (Bieñkowski and Marsza³ek 1974), which should allow subniveallyactive individuals to reduce some of the thermal costs of being solitary (West and Dublin 1984).…”

“…However, in the case of the C. nivalis, the associated costs of local trophic restrictions in the alpine zone (Bieñkowski and Marsza³ek 1974) could modulate the type of social strategy adopted (Ostfeld 1985b). Indeed, snow voles present much better insulatory properties than other microtines from lower altitudes as the bank vole Clethrionomys glareolus or the common vole Microtus arvalis (Bieñkowski and Marsza³ek 1974), which should allow subniveallyactive individuals to reduce some of the thermal costs of being solitary (West and Dublin 1984). Additionally, C. nivalis predominantly uses the cavernicolous microhabitats created by permanent rocky formations throughout the year and it may benefit from the stable, mainly stenothermic, microclimatic conditions of such structures (Kryštufek and Kovaciè 1989).…”

“…and discontinuously distributed from SW Europe to Iran (Krapp 1982, Amori 1999. Considered to be a glacial relict, this species is highly adapted to a petricolic way of life (Bieñkowski and Marsza³ek 1974), typically inhabiting natural rocky formations located on open slopes (Janeau 1980, Krapp 1982. Similarly to many other microtines (see reviews at Ostfeld 1990, Tamarin et al 1990), adult C. nivalis exhibit stable home ranges during the summer reproductive period (Le Louarn and Janeau 1975) and are considerably aggressive to each other, specially at the intrasexual level (eg Luque-Larena et al 2001).…”

Diurnal patterning of eight activities in 14 species of muroid rodents

“…allenis range from 2.20 to 3.14 (Bienkowski & Marszalek, 1974;Daan & Slopsema, 1978;Gorecki, 1968;Hanson & Grodzinski, 1970;Packard, 1968; A. M. Pearson, 1962; O. P. Pearson, 1947;Wiegert, 1961; McNab, Note 3). Such disparity between genera appears to be correlated with the periodicity of activity patterns for the genera.…”