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Concept: Winter


In anurans reproductive behavior is strongly seasonal. During the spring, frogs emerge from hibernation and males vocalize for mating or advertising territories. Female frogs have the ability to evaluate the quality of the males' resources on the basis of these vocalizations. Although studies revealed that central single torus semicircularis neurons in frogs exhibit season plasticity, the plasticity of peripheral auditory sensitivity in frog is unknown. In this study the seasonally plasticity of peripheral auditory sensitivity was test in the Emei music frog Babina daunchina, by comparing thresholds and latencies of auditory brainstem responses (ABRs) evoked by tone pips and clicks in the reproductive and non-reproductive seasons. The results show that both ABR thresholds and latency differ significantly between the reproductive and non-reproductive seasons. The thresholds of tone pip evoked ABRs in the non-reproductive season increased significantly about 10 dB than those in the reproductive season for frequencies from 1 KHz to 6 KHz. ABR latencies to waveform valley values for tone pips for the same frequencies using appropriate threshold stimulus levels are longer than those in the reproductive season for frequencies from 1.5 to 6 KHz range, although from 0.2 to 1.5 KHz range it is shorter in the non-reproductive season. These results demonstrated that peripheral auditory frequency sensitivity exhibits seasonal plasticity changes which may be adaptive to seasonal reproductive behavior in frogs.

Concepts: Frequency, Hertz, Season, Sound, Spring, Frog, Winter, Seasons


It has been proposed that neonatal thyroid-stimulating hormone (TSH) concentrations are a good indicator of iodine deficiency in the population. A frequency of neonatal TSH concentrations above 5 mU/L below 3% has been proposed as the threshold indicating iodine sufficiency. The objective of the present study was to evaluate feasibility and usefulness of nation-wide neonatal TSH concentration screening results to assess iodine status in Belgium. All newborns born in Belgium during the period 2009-2011 (n = 377713) were included in the study, except those suffering from congenital hypothyroidism and premature neonates. The frequency of neonatal TSH concentrations above 5 mU/L from 2009 to 2011 in Belgium fluctuated between 2.6 and 3.3% in the centres using the same TSH assay. There was a significant inverse association between neonatal TSH level and birth weight. The longer the duration between birth and screening, the lower the TSH level. Neonatal TSH levels were significantly lower in winter than in spring or autumn and significantly lower in spring and summer than in autumn while significantly higher in spring compared to summer. In conclusion, despite that pregnant women in Belgium are mildly iodine deficient, the frequency of neonatal TSH concentrations above 5 mU/L was very low, suggesting that the neonatal TSH threshold proposed for detecting iodine deficiency needs to be re-evaluated. Although neonatal TSH is useful to detect severe iodine deficiency, it should not be recommended presently for the evaluation of iodine status in mildly iodine deficient regions.

Concepts: Pregnancy, Childbirth, Infant, Thyroid-stimulating hormone, Hypothyroidism, Pediatrics, Winter, Cretinism


Feeding stations are commonly used to sustain conservation programs of scavengers but their impact on behaviour is still debated. They increase the temporal and spatial predictability of food resources while scavengers have supposedly evolved to search for unpredictable resources. In the Grands Causses (France), a reintroduced population of Griffon vultures Gyps fulvus can find carcasses at three types of sites: 1. “light feeding stations”, where farmers can drop carcasses at their farm (spatially predictable), 2. “heavy feeding stations”, where carcasses from nearby farms are concentrated (spatially and temporally predictable) and 3. open grasslands, where resources are randomly distributed (unpredictable). The impact of feeding stations on vulture’s foraging behaviour was investigated using 28 GPS-tracked vultures. The average home range size was maximal in spring (1272±752 km(2)) and minimal in winter (473±237 km(2)) and was highly variable among individuals. Analyses of home range characteristics and feeding habitat selection via compositional analysis showed that feeding stations were always preferred compared to the rest of the habitat where vultures can find unpredictable resources. Feeding stations were particularly used when resources were scarce (summer) or when flight conditions were poor (winter), limiting long-ranging movements. However, when flight conditions were optimal, home ranges also encompassed large areas of grassland where vultures could find unpredictable resources, suggesting that vultures did not lose their natural ability to forage on unpredictable resources, even when feeding stations were available. However during seasons when food abundance and flight conditions were not limited, vultures seemed to favour light over heavy feeding stations, probably because of the reduced intraspecific competition and a pattern closer to the natural dispersion of resources in the landscape. Light feeding stations are interesting tools for managing food resources, but don’t prevent vultures to feed at other places with possibly high risk of intoxication (poison).

Concepts: Intraspecific competition, Scarcity, Foraging, Winter, Vulture, Gyps, Griffon Vulture, Home range


In winter, foraging activity is intended to optimize food search while minimizing both thermoregulation costs and predation risk. Here we quantify the relative importance of thermoregulation and predation in foraging patch selection of woodland birds wintering in a Mediterranean montane forest. Specifically, we account for thermoregulation benefits related to temperature, and predation risk associated with both illumination of the feeding patch and distance to the nearest refuge provided by vegetation. We measured the amount of time that 38 marked individual birds belonging to five small passerine species spent foraging at artificial feeders. Feeders were located in forest patches that vary in distance to protective cover and exposure to sun radiation; temperature and illumination were registered locally by data loggers. Our results support the influence of both thermoregulation benefits and predation costs on feeding patch choice. The influence of distance to refuge (negative relationship) was nearly three times higher than that of temperature (positive relationship) in determining total foraging time spent at a patch. Light intensity had a negligible and no significant effect. This pattern was generalizable among species and individuals within species, and highlights the preponderance of latent predation risk over thermoregulation benefits on foraging decisions of birds wintering in temperate Mediterranean forests.

Concepts: Light, Sun, Bird, Forest, Woodland, Winter, Savanna


The Eastern, migratory population of monarch butterflies (Danaus plexippus), an iconic North American insect, has declined by ~80% over the last decade. The monarch’s multi-generational migration between overwintering grounds in central Mexico and the summer breeding grounds in the northern U.S. and southern Canada is celebrated in all three countries and creates shared management responsibilities across North America. Here we present a novel Bayesian multivariate auto-regressive state-space model to assess quasi-extinction risk and aid in the establishment of a target population size for monarch conservation planning. We find that, given a range of plausible quasi-extinction thresholds, the population has a substantial probability of quasi-extinction, from 11-57% over 20 years, although uncertainty in these estimates is large. Exceptionally high population stochasticity, declining numbers, and a small current population size act in concert to drive this risk. An approximately 5-fold increase of the monarch population size (relative to the winter of 2014-15) is necessary to halve the current risk of quasi-extinction across all thresholds considered. Conserving the monarch migration thus requires active management to reverse population declines, and the establishment of an ambitious target population size goal to buffer against future environmentally driven variability.

Concepts: United States, Mexico, North America, Winter, Danaus, Jan Krzysztof Kluk, Nymphalidae, Monarch


Since physical inactivity especially prevails during winter months, we set out to identify outdoor alternatives to indoor cycling (IC) by comparing the metabolic and cardiorespiratory responses during alpine skiing (AS), cross-country skiing (XCS) and IC and analyse the effects of sex, age and fitness level in this comparison. Twenty one healthy subjects performed alpine skiing (AS), cross-country skiing (XCS), and IC. Oxygen uptake (VO2), total energy expenditure (EE), heart rate (HR), lactate, blood glucose and rate of perceived exertion (RPE) were determined during three 4-min stages of low, moderate and high intensity. During XCS and IC VO2max and EE were higher than during AS. At least 2½ hours of AS are necessary to reach the same EE as during one hour of XCS or IC. HR, VO2, lactate, and RPEarms were highest during XCS, whereas RPEwhole-body was similar and RPElegs lower than during AS and IC, respectively. Weight adjusted VO2 and EE were higher in men than in women while fitness level had no effect. Male, fit and young participants were able to increase their EE and VO2 values more pronounced. Both AS and XCS can be individually tailored to serve as alternatives to IC and may thus help to overcome the winter activity deficit. XCS was found to be the most effective activity for generating a high EE and VO2 while AS was the most demanding activity for the legs. Key pointsDuring cross-country skiing and indoor cycling VO2max and energy expenditure were higher than during alpine skiingApproximately 2½ hours of alpine skiing are necessary to reach the same energy expenditure of one hour of cross-country skiing or indoor cycling.Alpine skiing and cross-country skiing can be individually tailored to serve as sports alternatives in winter to activity deficit.By applying different skiing modes as parallel ski steering, carving long radii and short turn skiing, metabolic and cardiorespiratory response can be increased during alpine skiing.Male, fit and young participants were able to increase their energy expenditure and VO2 more pronounced with an increase in intensity compared with their counterparts.

Concepts: Energy, Cross-country skiing, Alpine skiing, Ski touring, Telemark skiing, VO2 max, Ski binding, Winter


BACKGROUND: Prior studies have suggested that the darkness of winter impacts the level of mental distress and sleeping problems. Our study investigated whether people living in the sub-arctic had more sleeping problems or mental distress during winter. METHODS: The cross sectional population Troms[latin small letter o with stroke] Study was conducted in Troms[latin small letter o with stroke], North Norway, at 69.4 degrees North and above the Arctic Circle. The study included entire birth cohorts and random samples of the population aged 30 to 87 years. Data was collected continuously from 1 October 2007 to the end of December 2008 except July. 8951 persons completed questionnaires including the HSCL-10 and the MCTQ. RESULTS: There were no significant differences in the reporting of current mental distress depending on season. Significantly more reported current sleeping problems in winter than in the other seasons, and less sleeping problems was found in spring. CONCLUSIONS: In this sub-arctic population, insomnia was most prevalent in winter, but there were no significant seasonal differences in mental distress. Although some people in the sub-arctic clearly are mentally negatively affected by the darkness of winter, the negative impact of winter on mental distress for the adult population is not conclusive.

Concepts: Season, Norway, Arctic Ocean, Arctic, Spring, Winter, Arctic Circle, Tromsø


During 2010-2015, a total of 2,244 deaths resulted from unintentional carbon monoxide poisoning, with the highest numbers of deaths each year occurring in winter months. In 2015, a total of 393 deaths resulting from unintentional carbon monoxide poisoning occurred, with 36% of the deaths occurring in December, January, or February.

Concepts: Hemoglobin, Oxygen, Carbon monoxide, Carbon monoxide poisoning, Winter


Edible dormice are arboreal rodents adapted to yearly fluctuations in seed production of European beech, a major food source for this species. In years of low beech seed abundance, dormice skip reproduction and non-reproductive dormice fed ad libitum in captivity can display summer dormancy in addition to winter hibernation. To test whether summer dormancy, that is, a very early onset of hibernation, actually occurs in free-living dormice, we monitored core body temperature (T b) over ~12 months in 17 animals during a year of beech seeding failure in the Vienna Woods. We found that 8 out of 17 dormice indeed re-entered hibernation as early as in June/July, with five of them having extreme hibernation durations of 11 months or more (total range: 7.8-11.4 months). Thus, we show for the first time that a free-living mammal relying on natural food resources can continuously hibernate for >11 months. Early onset of hibernation was associated with high body mass in the spring, but the distribution of hibernation onset was bimodal with prolonged hibernation starting either early (prior to July 28) or late (after August 30). This could not be explained by differences in body mass alone. Animals with a late hibernation onset continued to maintain high nocturnal T b’s throughout summer but used short, shallow torpor bouts (mean duration 7.44 ± 0.9 h), as well as occasional multiday torpor for up to 161 h.

Concepts: Seed, Bat, Ethology, Winter, Torpor, Hibernation, Dormouse, Edible dormouse


Rates of acute intracerebral hemorrhage (ICH) increase in winter months but the magnitude of risk is unknown. We aimed to quantify the association of ambient temperature with the risk of ICH in the Intensive Blood Pressure Reduction in Acute Cerebral Haemorrhage Trial (INTERACT2) participants on an hourly timescale.

Concepts: Blood, Stroke, Bleeding, The Association, Subarachnoid hemorrhage, Cerebral hemorrhage, Winter, Coagulopathy