Beginning Of Hibernation Research Articles

Caterpillar loss through grassland harvest differs between two related butterfly species of conservation concern

Abstract Temperate, semi‐natural grasslands emerged from traditional land use and are recognised for their outstanding biodiversity. However, these grasslands severely declined due to agricultural industrialisation. Accordingly, specialised species of nutrient‐poor grasslands like the closely related butterflies Nickerls Fritillary Melitaea aurelia Nickerl, 1850 and Marsh Fritillary Euphydyras aurinia (Rottemburg, 1775) (Lepidoptera: Nymphalidae) have experienced strong declines in the last century due to grassland loss and deterioration. Here, we studied for the first time the effects of the complete harvest process in grasslands from mowing until the removal of the cut vegetation on the survival of their caterpillars. To assess survival rates, we sampled larvae of both species and environmental conditions before and after the harvest process and analysed the results using generalised linear mixed‐effects models. Our study revealed that the harvest process in grasslands mown once by bar mowers resulted in substantial caterpillar loss influenced by (i) growth form of the host plants and (ii) timing of grassland harvest. Accordingly, the host plant of E. aurinia, Succisa prantensis, lost nearly half of its leaves during the harvest process, while late harvesting was especially harmful for caterpillars already commencing hibernation. Overall, E. aurinia had higher losses compared with M. aurelia, and these were most severe in late‐mown moist meadows. To increase the survival rate of E. aurinia, we recommend mowing before the beginning of hibernation using bar mowers. Complementary, or if mowing is done later, at least 20% of the meadow should be left as an untouched refuge in a spatially rotating manner.

ВТОРИЧНЫЕ МЕТАБОЛИТЫ И АСПАРАГИНОВАЯ КИСЛОТА В МОЗГЕ АМФИБИЙ R. TEMPORARIA КАК НИЗКОТЕМПЕРАТУРНЫЕ АДАПТОГЕНЫ

Previously, we have demonstrated that such secondary metabolites as phosphoethanolamine (PE) and phosphoserine (PS) are low-temperature adaptogens specific to the brain of freshwater fish, in contrast to taurine which serves as an adaptogen in fish muscles and blood plasma. Here, we carry on investigating the role of PE, PS, taurine and proteinogenic amino acids in adaptation of poikilothermic animals to low temperatures. PE and PS were discovered in the brain of the frog Rana temporaria, and their pools were shown to increase by the be- ginning of hibernation compared to the summer period almost in a similar manner (PE – from 0.22 to 1.65, PS – from 0.29 to 1.98 μ mol/g wet weight). Unlike the fish brain, in the R. temporaria brain, the PE/PS ratio is almost indistinguishable in winter compared to summer. In contrast to fish, in the R. temporaria brain the taurine level increases from 0.77 in summer to 1.37 μ mol/g in winter. The level of aspartic acid, which is missing in the fish brain during winter, in the R. temporaria brain sharply increases by the beginning of hibernation from 0.86 to 4.60 μmol/g. Thus, there is ground to believe that such secondary metabolites as PE, PS, taurine and proteinogenic aspartic acid play the role of low-temperature adaptogens in the brain of anuran amphibians.

Seasonal oxidative capacity of skeletal muscles in hibernating Daurian ground squirrels (Spermophilus dauricus)

We investigated the mechanism of high oxidative capacity of skeletal muscles in hibernating Daurian ground squirrels (Spermophilus dauricus Brandt, 1843). Myoglobin (Mb) levels, as well as citrate synthase and lactate dehydrogenase (LDH) activities, were measured by spectrophotometry. Mb content in the soleus (SOL) muscle lasted from the beginning of hibernation to spring. Mb content in SOL was 87% higher in the hibernating group than in the summer group. Mb content in the extensor digitorum longus (EDL) muscle stayed at similar levels during the different periods of the year. Citrate synthase activity in SOL was 30% higher in the hibernating group than in the summer group. Meanwhile, citrate synthase activity in EDL did not change during hibernation. LDH activity in SOL was not different between the hibernating group and the summer active group, whereas LDH activity in EDL increased significantly (up to 11%) in the 2 days arousal after hibernation group compared with the hibernating group. We conclude that high oxidative capacity is provided by increased oxygen storage capacity of slow-twitch muscle fibers rather than from fast-twitch muscle fibers in hibernating animals.

Age and sex differences in hibernation patterns in free-living Anatolian ground squirrels

Anatolian ground squirrels, Spermophilus xanthoprymnus (Bennett, 1835), are nearly endemic to Turkey. Various aspects of the biology of Anatolian ground squirrels have been studied. However, a detailed description of hibernation, with special attention to age and sex differences, has not previously been reported. Thus, in this study, we aimed to present a detailed description of hibernation in a population of free-living Anatolian ground squirrels, with special attention to age and sex differences, in relation to soil temperature (Tsoil) at the expected depth of the hibernacula. This study is the first such study for Old World ground squirrels (the genus Spermophilus sensu stricto) and incorporates an additional species from a different environment (e.g. warmer than those of others) into comparative studies of hibernation patterns in Holarctic ground squirrels (the tribe Marmotini) under natural conditions. Body temperature (Tb) was continuously recorded from late summer to spring by intraperitoneally implanted temperature loggers and Tsoil by a temperature logger at a depth of 1m in the field. Anatolian ground squirrels spent about half of the year in hibernation. However, differences in timing of the beginning and end of hibernation resulted in differences in the duration of hibernation among age-sex classes. The duration of torpor bouts was short at the beginning of hibernation, increased as Tsoil decreased, reached its maximum toward the end of hibernation, and decreased thereafter. Adult males exhibited hibernation characteristics rather different from those of other age-sex classes, spending less time in hibernation, exhibiting shorter torpor bouts and longer interbout arousals, especially toward the end of hibernation, and spending proportionally less time in torpor. In conclusion, we observed that hibernation patterns in free-living Anatolian ground squirrels were influenced by age-sex classes, as well as environmental conditions.

Diet of the fat dormouse (Glis glis) on the northern periphery of its distributional range

We studied the seasonal and annual variation in diet composition of the fat dormouse (Glis glis) in Lithuania, a locality situated on the northern periphery of the dormouse range and outside of the range of the European beech (Fagus sylvatica). After emergence from hibernation, dormice fed on oak acorns (from the previous year), inflorescences of various trees, vegetative parts of plants and food of animal origin (birds, their eggs and insects). In June, soft mast and seeds of birches supplemented the dormouse diet, and diet composition was the most diverse during this period. In July, raspberries and fruits of glossy buckthorn constituted the bulk of dormouse diet, but seeds of birches dominated in a specific year. Hard mast (mainly acorns) dominated the diet of G. glis from August until the beginning of hibernation in October. A high prevalence of acorns, comparatively high proportion of birch seeds and low proportion of food of animal origin in the diet, as well as feeding on fruits of glossy buckthorn, are specific features of feeding by G. glis in Lithuania. The diet of G. glis on the northern periphery of its range resembles its diet on the eastern periphery of the range where beech trees are also absent. According to the composition of G. glis diet, feeding conditions in both of these peripheral regions are poorer in comparison to central or southern regions.

Energetics of hibernation and reproductive trade-offs in brown bears

Brown bears give birth and nurture their young for the first 3–5 months while fasting in hibernation. During this period, bears use body reserves to support the energy and protein costs of reproduction. Limited reserves may restrict reproductive investment. We developed a model to assess the energetic costs of reproduction during hibernation and to determine how maternal condition, length of lactation, litter size, and length of hibernation affect brown bear reproductive success. Increasing litter size by one cub was more costly than increasing the lactation period by 14 days. For hibernating females, ∼73% of their mass loss during lactation was lean mass. Minimum levels of fat reserves necessary to support reproduction varied from 19% to 33% depending on number of cubs and length of lactation while denned. Reproduction was not possible if body fat content was below 19% and length of hibernation was over 120 days. While the importance of fat or energy reserves at the beginning of hibernation has been long recognized, the importance of consuming high-protein foods after hibernation may be equally important. Therefore, more attention should be given to understanding pre- and post-hibernation nutritional factors affecting reproduction and the trade-offs between available food resources, maternal condition, and reproductive investment and success in wild bear populations.

Body temperature patterns and use of torpor in an alpine glirid species, woolly dormouse

Woolly dormice, Dryomys laniger Felten and Storch (Senckenbergiana Biol 49(6):429–435, 1968), are a small (20–30 g), omnivorous (mainly insectivorous), nocturnal glirid species endemic to Turkey. Although woolly dormice have been assumed to hibernate during winter, no information exists on body temperature patterns and use of torpor in the species. In the present study, we aimed to determine body temperature patterns and use of torpor in woolly dormice under controlled laboratory conditions. Accordingly, body temperature (Tb) of woolly dormice was recorded using surgically implanted Thermochron iButtons, small and inexpensive temperature-sensitive data loggers. Woolly dormice exhibited robust, unimodal daily Tb rhythmicity during the euthermic stage before the beginning of hibernation. They displayed short torpor before they began hibernation, although the tendency to enter short torpor was different among individuals. Woolly dormice began hibernation within 1–3 days after exposure to cold and darkness, i.e., on October 22–24, and ended hibernation in the first half of April. Hibernation consisted of a sequence of multiday torpor bouts, interrupted by euthermic intervals. Thus, the patterns of hibernation in woolly dormice were similar to those observed in classical hibernating mammals.

Antennal sugar sensitivity in the click beetle Agriotes obscurus

The occurrence of salt‐, sugar‐sensitive neurones and a mechanoreceptor neurone in the antennal hair‐like gustatory sensilla of the click beetle Agriotes obscurus L. (Coleoptera, Elateridae) is demonstrated using the electrophysiological sensillum tip‐recording technique. The stimulating effect of 13 water soluble sugars at 100 mm is tested on the neurones of these sensilla. Sucrose and fructose are the two most stimulating sugars for the sugar‐sensitive neurone, evoking almost 30 spikes s−1 at 100 mm. The stimulating effect of arabinose, glucose, mannose, maltose and raffinose is three‐ to five‐fold lower, in the range 5.9–9.6 spikes s−1. The remaining six sugars, xylose, galactose, rhamnose, cellobiose, trehalose and lactose, have very low (<1 spikes s−1) or no ability to stimulate the sugar‐sensitive neurone. Concentration/response curves of the sugar‐sensitive neurone to sucrose, fructose and glucose at 0.01–100 mm overlap to a large extent in hibernating, cold reactivated and reproductively‐active beetles. A remarkable 9–50% decrease in the number of spikes evoked by 100 mm fructose and 10–100 mm sucrose occurs, however, in reproductively‐active beetles in June compared with beetles at the beginning of hibernation in October. These findings show that A. obscurus is capable of sensing a wide range sugars via their antennal gustatory sensilla.

Morphofunctional changes in the small intestine epithelium of the frog Rana temporaria in the course of hibernation

The structure and function of small intestine epithelium have been studied in overwintering frogs at various stages of hibernation. Experiments on the in vitro absorption of arginine vasotocin (AVT) have shown that the epithelium ability for absorption of this nonapeptide without hydrolysis persists during hibernation. However, there is a decline in AVT absorption observed in January–February and later on (as compared with that in October–December) which is most pronounced in March–April. Changes in the epithelial structure appear by midwinter and are growing towards spring. In April–May, enterocyte height decreased by 33%, microvilli length by 40%, and number of mitochondria by 57% relative to the values at the beginning of hibernation. The absence of signs of breakdown attests to the adaptive nature of the observed changes. The dynamics of the studied parameters reveals morphological and functional plasticity of small intestinal epithelium in Rana temporaria over the hibernation period.

Intensity of parasitic mite infection decreases with hibernation duration of the host snail

Temperature can be a limiting factor on parasite development. Riccardoella limacum, a haematophagous mite, lives in the mantle cavity of helicid land snails. The prevalence of infection by R. limacum in populations of the land snail Arianta arbustorum is highly variable (0-78%) in Switzerland. However, parasitic mites do not occur in host populations at altitudes of 1290 m or higher. It has been hypothesized that the host's hibernation period might be too long at high elevations for mites and their eggs to survive. To test this hypothesis, we experimentally infected snails and allowed them to hibernate at 4°C for periods of 4-7 months. Winter survival of host snails was negatively affected by R. limacum. The intensity of mite infection decreased with increasing hibernation duration. Another experiment with shorter recording intervals revealed that mites do not leave the host when it buries in the soil at the beginning of hibernation. The number of mites decreased after 24 days of hibernation, whereas the number of eggs attached to the lung tissue remained constant throughout hibernation. Thus, R. limacum survives the winter in the egg stage in the host. Low temperature at high altitudes may limit the occurrence of R. limacum.

The effect of cold shock on the free amino acid pool of rotan pondfish Perccottus glehni (Eleotridae, Perciformes)

The effect of cold shock on the free amino acid pool of the pondfish P. glehni not adapted to hibernation has been studied. In the beginning of September, after four days of cold shock, a decrease in the blood level of essential amino acids and an increase in the level of alanine and three-fold increase in the level of γ-aminobutyric acid (GABA) were observed. Changes in the free amino acid pool in the mussels occur in two stages. Namely, in a considerable decrease in their concentration after two days of cold shock followed by an even more significant increase in their amount after four days of shock. In the brain changes in the free amino acid pools are associated with their total decrease followed by continuous significant decrease in the level of taurine during the first four days of cold shocking. The obtained results are compared with previously obtained data on the free amino acid content in muscles and blood of P. glehni during preparation for winter sleep and the beginning of hibernation.

Energy homeostasis regulatory peptides in hibernating grizzly bears

Event Abstract Back to Event Energy homeostasis regulatory peptides in hibernating grizzly bears Jànos Gardi1*, O. L. Nelson2, Charles T. Robbins3, Éva Szentirmai4, Levente Kapás4 and James M. Krueger5 1 University of Szeged, First Department of Internal Medicine, Hungary 2 Washington State University, Department of Veterinary Clinical Sciences, United States 3 Washington State University, Department of Natural Resource Sciences and School of Biological Sciences, United States 4 Washington State University, WWAMI Medical Education Program, United States 5 Washington State University, Department of VCAPP, United States Many mammals undergo an unique state of energy conservation in response to harsh climatic conditions. Grizzly bears (Ursus arctos horribilis) do not eat, drink, urinate, or defecate and demonstrate minimal activity during their annual 4-6 months hibernation period. The aim of our study was to determine the potential role of ghrelin, leptin, obestatin, and neuropeptide-Y (NPY) in the regulation of energy homeostasis during hibernation in grizzly bears. Blood samples were collected during the active summer, early-hibernation (first 2 months of hibernation, n = 10 for each period) and the late-hibernation periods (4 months after the beginning of hibernation, n = 4). Radioimmunoassays were used to measure plasma hormone levels. We found that plasma ghrelin concentrations were significantly lower during hibernation than during the summer. Obestatin and NPY levels did not change between pre-hibernation and hibernation. Plasma leptin tended to decrease during late-hibernation relative to active and early-hibernation periods. Ghrelin is involved in the short-and long-term regulation of energy balance by stimulating food intake, reducing lipolysis, and suppressing energy expenditure. High ghrelin levels may help enhancing the accumulation of fat during pre-hibernation, while the lower ghrelin concentrations during hibernation period may increase lipolysis and give the animals a satiety signal. Same pattern of ghrelin levels were found in the racoon dog which capable of sleeping through the winter. The falling leptin levels at the end of the hibernation period could be important in energy preservation. Our results provide evidence that ghrelin and leptin could play a role in the regulation of energy homeostasis during hibernation. Keywords: comparative endocrinology Conference: 25th Conference of the European Comparative Endocrinologists, Pécs, Hungary, 31 Aug - 4 Sep, 2010. Presentation Type: Conference Presentation Topic: Comparative endocrinology Citation: Gardi J, Nelson OL, Robbins CT, Szentirmai É, Kapás L and Krueger JM (2010). Energy homeostasis regulatory peptides in hibernating grizzly bears. Front. Endocrinol. Conference Abstract: 25th Conference of the European Comparative Endocrinologists. doi: 10.3389/conf.fendo.2010.01.00078 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 31 Aug 2010; Published Online: 31 Aug 2010. * Correspondence: Dr. Jànos Gardi, University of Szeged, First Department of Internal Medicine, Szeged, Hungary, gardi@endoc.szote.u-szeged.hu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Jànos Gardi O. L Nelson Charles T Robbins Éva Szentirmai Levente Kapás James M Krueger Google Jànos Gardi O. L Nelson Charles T Robbins Éva Szentirmai Levente Kapás James M Krueger Google Scholar Jànos Gardi O. L Nelson Charles T Robbins Éva Szentirmai Levente Kapás James M Krueger PubMed Jànos Gardi O. L Nelson Charles T Robbins Éva Szentirmai Levente Kapás James M Krueger Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Glycemia and free sugar levels of the goby Perccottus glehni depending on period before the beginning and after the end of hibernation

Goby Perccottus glehni is one of the most winterhardy species of fresh-water eurythermal fish. Study of grounds of biochemical adaptation of these animals to hibernation under conditions of ice, which are currently absent, are of undoubted for understanding of the nature of hypometabolic states. This work deals with a study of changes in the content of glucose and other free sugars in goby blood and muscle tissue under different physiological states: active, prehibernation, and arousal after experimental cooling to negative near-zero temperature. (1) A relatively high glycemia level with fluctuation amplitude from 9.8 +/- 2.1 to 24.4 +/- 2.4 mmol/ml is revealed. The minimal value of these fluctuations is recorded at the period almost coinciding with beginning of hibernation, while the maximal value--at the period of artificial termination of the three-month hibernation in ice at -1.5 degrees C. The high blood glycemia level correlating with that in the muscle tissue might probably be due to the protector role of this sugar in adaptive mechanisms of the studied fish not much to winter hypothermia, but rather to the winter hibernation on ice. (2) The level of disaccharide maltose in muscle tissue that is maximal in April is predominantly in reciprocal dependence on the fructose content that is maximal in July. (3) Dynamics of changes in the mono- and disaccharide content depending on the stage of preparation of hibernation basically coincided with the previously revealed dynamics for the fresh-water mollusc Lymnaea stagnalis, which indicated homology of mechanisms of the low-temperature adaptation for animals of different phylogenetic levels.

O-glycosylhydrolases of embryos of the sea urchin Strongylocentrotus intermedius and effect of some natural substances on their biosynthesis

The fresh-water fish gobi Perccottus glehni survives after wintering in ponds frozen in winter until the very bottom. In adaptation of poikilothermal animals to wintering at nearzero temperatures, an essential role is played by free amino acids: accumulation of a high amount of some particular acid at the period of preparation to the state of hibernation can indicate its protector role in the low-temperature adaptation. In the present wok it has been shown that as early as by the end of August in the gobi muscle there occurs a 3-fold increase, as compared with that in July, of concentration of taurine whose pool after this accounts for 50 % of the total pool of the muscle tissue free amino acids. During December and after the 3-month hibernation in ice, it exceeded the April and July level 8 and 4 times, respectively, and amounted to 50 % of the total free amino acid pool for muscle and to 40 % for blood. Several days before the beginning of hibernation under natural conditions, both in blood and in muscle there was revealed disappearance of a sharp decrease of essential amino acid concentrations. An essential peculiarity of the change composition of free amino acids after hibernation was a significance increase of alanine concentration in muscle - 3.5 times as compared with that in July and 1.4-1.8 times as compared with December measurements. The total pool of free amino acids in muscle as compared with that in July rose in December almost 1.5 times (34.76 +/- 1.12 micromole/g wet weight), while after hibernation - 2 times. Peculiarities of the taurine accumulation before the onset of winter colds allow suggesting that the role taurine consists in provision of a possibility of survival of eurithermal fish at the nearzero temperatures.

Seasonal Inactivity of the Desert Box Turtle, Terrapene ornata luteola, at the Species' Southwestern Range Limit in Arizona

At its southwestern range limit in southeastern Arizona, the Desert Box Turtle Terrapene ornata luteola, takes refuge in subterranean mammal burrows, primarily those of the Kangaroo Rat Dipodomys spectabilis, from November through June. I inferred temporal and physiological characteristics of turtles in burrows from temperatures collected with miniature data loggers buried in the soil and attached to turtles from August 2001 through June 2003. In the fall, entrance into hibernation varied among individual turtles and between years from 18 October to 6 December. Mean daily body temperatures at the beginning of hibernation were about 14-188C. From December through February, body temperatures averaged about 98C and were slightly less than and highly correlated with the 30-cm soil temperature. By April, body temperatures of turtles approached levels exhibited by surface-active turtles (minimum approximately 188C for moving turtles) but turtles did not emerge from burrows until the summer monsoons began about three months later. Thus, the five-month hibernation period of T. o. luteola was contiguous with a three-month estivation period for a total annual period of subterranean refuge of about eight months. Except for extending into warm months, the annual inactive period of T. o. luteola in southeastern Arizona was not remarkably different from that in other parts of the species' range. In arid southeastern Arizona, populations of Terra- pene ornata, primarily a prairie-adapted form (Legler, 1960; Dodd, 2001), are at the species' southwestern range limit and may be active for only a few weeks out of the year. In seasonally cold or dry environments, reptiles commonly spend a substantial portion of the year awaiting favorable weather in hibernation or estivation (Gregory, 1982). Furthermore, in areas such as southeastern Arizona, contiguous periods of cold and hot dry seasons may produce an extended period of weather conditions unfavorable for surface activity. With low annual reproductive output and the lowest field metabolic rates reported for any reptile, Terrapene have the potential to be highly successful in unpredict- able resource environments (Penick et al., 2002). Legler (1960) hypothesized that extreme southwestern pop- ulations of T. ornata, formally recognized as Terrapene ornata luteola, were likely to be physiologically adapted for living in rigorous arid environments. However, activity and thermal biology of T. o. luteola during the activity season in southeastern Arizona did not differ substantially from that in more central prairie portions of the species' range (Plummer, 2003). In this paper, I show that certain temporal and thermal aspects of hibernation of T. o. luteola in southeastern Arizona are also not exceptional; however, hibernation is followed by an estivation period that results in a major portion of the annual cycle being spent inactive in underground refugia.

Variation in survival rates for the alpine marmot (Marmota marmota): effects of sex, age, year, and climatic factors

We examined variation in annual survival rates in a population of alpine marmots (Marmota marmota) according to intrinsic (sex and age) and extrinsic (year and climate) factors. We tested predictions concerning (i) a sex effect in a monogamous non-dimorphic species, (ii) age structure of survival rates in a mesomammal, and (iii) the annual variability effect and the contribution of stochastic climatic factors, especially snow cover, frost, and rainfall. We used a 8-year dataset of 367 marmots that were livetrapped and marked in La Sassière Nature Reserve in the French Alps between 1990 and 1997. Survival and recapture rates were modelled using recent developments in capture–recapture models. Sex had no effect on survival rates, which agrees with the predictions of sexual selection. Survival rates for young of the year (YOY, from weaning to first birthday) were, on average, lower than in the older age class. In the older age class, annual variation occurred that was strongly related to the intensity of autumn frost. By determining the soil temperature at the beginning of hibernation, this factor, though short-lived, could have determined the energetic cost of hibernation. Neither annual variation nor an environmental effect was detected in YOY despite a large sample size. Social thermoregulation could contribute to the stability of YOY survival rates. As infanticide was common after the immigration of a new dominant male, survival of YOY seemed to depend more on social events than on stochastic climatic ones.

INTERDEPENDENCY OF STORED FOOD AND CHANGES IN BODY TEMPERATURE DURING HIBERNATION OF THE EASTERN CHIPMUNK,TAMIAS STRIATUS

Duration of torpor by eastern chipmunks, Tamias striatus, kept at 5°C progressively increased at the beginning of hibernation (autumn phase), remained long and relatively constant (winter phase), and then decreased (spring phase) in a fashion similar to that observed in hibernators that store energy as body fat. Duration of bouts of torpor in winter and spring and amount of time animals hibernated before starting the energetically demanding spring phase were related inversely to amount of food provided at the beginning of the experiment. In addition, chipmunks given the least amount of food (400 g) continued to hibernate until they consumed all seeds; those provided with abundant food (5,000 g) terminated hibernation spontaneously early in the spring phase and remained euthermic thereafter. Animals given an intermediate ration (1,000 g) hibernated until food was gone (42%) or spontaneously terminated hibernation with abundant food uneaten (58%). Thermoregulatory responses of chipmunks appear more flexible than those of species that store energy as body fat, but the match between use and availability of energy during dormancy is imprecise.

Changes in plasma progesterone in female Vipera aspis L. (Reptilia, viperidae) during the sexual cycle in pregnant and nonpregnant females

The plasma progesterone concentration in female Vipera aspis changes during pregnancy and exhibits an increase before ovulation, a summer peak, a decrease up to parturition, and a new increase at the beginning of hibernation. For females in their first or second year after gestation, the evolution of plasma progesterone shows a spring peak and a summer peak. Whatever the stage of the sexual cycle, females present two annual periods of steroidogenic activity producing plasma progesterone: one in spring and one in summer. All data suggest an annual endogenous endocrinological cycle of reproduction, modulated by external factors (temperature, food availability). The origin of plasma progesterone and its control in the sexual cycle are discussed.

Evolution de la progestérone plasmatique chez la femelle Vipera berus L. (Reptilia: Viperidae) au cours du cycle sexuel

, In pregnant female Vipera berus, body weight increases slightly during the pregnancy. Parturition induces an average weight loss of 40 % . Plasma progesterone is high in July and decreases until September. The level of this hormone increases at the beginning of hibernation. A female which did not complete its gestation showed a rapid decrease of progesterone in July and, as with other gestating females that had given birth, a rise in November. In a nonpregnant female, the profile of plasma progesterone showed a peak in August. The control of progestrone in the sexual cycle is discussed.

Population studies, physiological state and mortality factors of overwintering adult populations of females ofCulex pipiensL. (Diptera: Culicidae)

AbstractThe biology of overwintering populations of adults ofCulex pipiensL. was studied between October 1977 and April 1980 in southern England. Data obtained from population studies showed that there was a rapid build-up at the beginning of hibernation in August, reaching a peak in late October-early November each year and gradually decreasing from December. Extensive movement both in and out and within the hibernation site occurred, with many individuals changing their locations or hibernacula during the course of hibernation. Studies on induced feeding showed that in the early months of hibernation (August-October) exposure to constant light for a minimum period of 12 days was required before the females would take a blood-meal. This period decreased during the course of hibernation. Observations on the physiological condition of hibernating females revealed that up to 90% of the population were inseminated. A few parous females entered hibernation shelters at the onset of winter but did not survive the winter. Furthermore, females used up about 80% of their fat food reserves during hibernation, while there was little or no change in the quantity of glycogen present. From an assessment of the impact of mortality factors on a population of known size, it was observed that exodus from the hibernation shelters accounted for about 30% reduction in the population size while depletion of food reserves and predation by spiders accounted for approximately 15 and 20% mortality, respectively.