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Winter Weather (winter + weather)
Selected AbstractsEffects of fat reserves on annual apparent survival of blackbirds Turdus merulaJOURNAL OF ANIMAL ECOLOGY, Issue 1 2003Mark W. Miller Summary 1Fat reserves are stored energy that may help birds survive periods of harsh winter weather. This hypothesis predicts that annual apparent survival is higher for birds with large fat reserves than for birds with few or no fat reserves in winter. 2Blackbirds (Turdus merula Linnaeus) were ringed in central Italy from 16 November to 20 February during 1990,2001. Fat scores were recorded for each bird. We used these capture,mark,recapture data for 1703 blackbirds to estimate the effect of large fat reserves on annual apparent survival, while controlling for transients, using computer programs surviv and mark. Probability of birds retaining large fat reserves, or retaining few fat reserves, over 2 successive years was also estimated. 3Birds with large fat reserves did not have higher estimated annual apparent survival than birds with few fat reserves (,,large= ,,few= 0·595, SE = 0·043), inconsistent with our prediction. No effects of age, sex or year were detected on annual apparent survival. Birds with few fat reserves in any given year tended to have few fat reserves the following year (, SE = 0·052). Birds with large fat reserves in any given year were unlikely to have large fat reserves the next year (, SE = 0·080). 4Large fat reserves may not increase annual survival of blackbirds wintering in central Italy. Winter weather in our study area may be too mild to effect survival. Alternatively, increased predation risk associated with large fat reserves may counteract any benefits of reduced starvation risk. [source] FC02.4 Meteorological factors and standard series patch test reactionsCONTACT DERMATITIS, Issue 3 2004Janice Hegewald The existence of seasonal patterns to patch test reactions has been described, but with conflicting causal interpretations. The potential seasonality of patch tests may be due to irritation, changes to skin barrier or changes to immunological functions caused by meteorological fluctuations. For example, increased skin irritability due to cold winter weather and low humidity may cause an increase in irritative/doubtful and weak positive (false positive) reactions. To investigate the extent of the association between weather and patch test results, consecutive patients (N = 73691) patch tested with the standard series of the German Contact Dermatitis Research Group (DKG) at German or Austrian IVDK (http://www.ivdk.de) centres were matched with weather data collected at a nearby (30 km radius) weather station. Temperature and absolute humidity (AH) on the day of patch test application and the two preceding days were averaged to represent the environment most likely to have influenced the skin condition at the time of testing. The results of 24 standard series substances were analyzed with multivariate logistic regression. Half of the standard series substances examined, including fragrance mix, nickel sulphate, and formaldehyde, exhibited evidence of a relationship with meteorological conditions. Fragrance mix and p-Phenylene diamine exhibited the strongest evidence of an association to weather, with the odds of the reactions in all three reaction categories (ir/?, +, ++/+++) increasing during winter conditions. Due to the association between weather and patch test reactivity, the potential effect of meteorological conditions should be considered in the interpretation of patch test reactions. [source] Supplemental feeding reduces natural selection in juvenile red deerECOGRAPHY, Issue 3 2002Karoline T. Schmidt In red deer, variation in winter and spring weather conditions encountered by the mothers during pregnancy and during the first year of life are a main determinant for individual life-history as well as population dynamics. We tested the hypothesis that supplementary feeding which provides constant food supply throughout winter removes the selective pressure of winter harshness on nutrition-mediated phenotypic traits. We analysed cohort variation in body weight in calves in October, before their first winter, and in yearlings in June, after their first winter, in a food-supplemented population in the Eastern Austrian Alps. Over eleven years, cohort body weight varied between years in calves and yearlings. Contrary to studies on non-supplemented red deer populations we found neither short- nor long-term effects of winter weather on body weight. In calves, autumn body weight was negatively related to April,May and June temperatures, suggesting that cool weather during the main growth period retarded plant senescence and thereby prolonged the period of high protein content of summer forage. In yearlings, variation in June body weight, shortly after the end of the feeding period, was lower after a wet April,May, suggesting a negative effect of a prolonged period of supplemental feeding. For both calves and yearlings intra-cohort variation in body weight was higher, inter-cohort variation was lower as compared to non-supplemented red deer, suggesting that in their first year of life supplemented red deer are under reduced natural selection pressure. [source] Population trends of widespread woodland birds in EuropeIBIS, Issue 2007RICHARD D. GREGORY We explore population trends of widespread and common woodland birds using data from an extensive European network of ornithologists for the period 1980,2003. We show considerable differences exist in the European trends of species according to the broad habitat they occupy and the degree to which they specialize in habitat use. On average, common forest birds are in shallow decline at a European scale; common forest birds declined by 13%, and common forest specialists by 18%, from 1980 to 2003. In comparison, populations of common specialists of farmland have declined moderately, falling on average by 28% from 1980 to 2003. These patterns contrast with that shown by generalist species whose populations have been roughly stable over the same period, their overall index increasing by 3%. There was some evidence of regional variation in the population trends of these common forest species. The most obvious pattern was the greater stability of population trends in Eastern Europe compared with other regions considered. Among common forest birds, long-distance migrants and residents have on average declined most strongly, whereas short-distance migrants have been largely stable, or have increased. There was some evidence to suggest that ground- or low-nesting species have declined more strongly on average, as have forest birds with invertebrate diets. Formal analysis of the species trends confirmed the influence of habitat use, habitat specialization and nest-site; the effects of region and migration strategy were less clear-cut. There was also evidence to show that year-to-year variation in individual species trends at a European scale was influenced by cold winter weather in a small number of species. We recommend that the species trend information provided by the new pan-European scheme should be used alongside existing mechanisms to review the conservation status of European birds. The analysis also allows us to reappraise the role of common forest bird populations as a potential barometer of wider forest health. The new indicator appears to be a useful indicator of the state of widespread European forest birds and might prove to be a useful surrogate for trends in forest biodiversity and forest health, but more work is likely to be needed to understand the interaction between bird populations and their drivers in forest. [source] Population dynamics of the pipistrelle bat: effects of sex, age and winter weather on seasonal survivalJOURNAL OF ANIMAL ECOLOGY, Issue 2 2003Thomas Sendor Summary 1Life-history theory assumes increased mortality at certain stages such as hibernation. However, seasonal variation of survival rates of hibernating mammals has rarely been estimated. In this study, apparent survival of pipistrelle bats (Pipistrellus pipistrellus) hibernating and performing summer swarming at a large hibernaculum (Marburg Castle, Hesse, Germany), was modelled using seasonal (summer/winter) capture,recapture data for the years 1996,2000. The spring survival interval includes the period of arousal at the end of hibernation and therefore validly measures survival associated with hibernation. 2In five summers and four winters, 15 839 bats were captured and released (13 082 individuals) and 3403 recaptures recorded. Analysis was complicated by transience and trap-dependence. Recapture rates varied seasonally and by group. The autumnal survival estimates were negatively biased due to transience effects that could not be taken into account. 3Survival could be modelled using two age-classes, with reduced first-year juvenile survival. The age effect persisted over the first autumn and spring. There was virtually no evidence for sex-specific survival rates; male and female survival were found to be almost equal. In the best-fitting models, survival rates varied over time and differed among sexes and age-classes by a constant amount. Between years, there was only a small variation in spring survival, which could not be explained by winter severity. 4Adult spring survival was surprisingly high, averaging 0·892 (= 0·028). No evidence for increased mortality during hibernation could be found. This contradicted the expectation of reduced over-winter survival due to depleted fat reserves at the end of hibernation. Thus, hibernation does apparently not entail a survival cost for the pipistrelle bat. Rough estimates of annual adult survival averaged 0·799 ( = 0·051), which considerably exceeds previous estimates; annual juvenile survival was estimated at 0·527 ( = 0·095). Hence, previous studies have substantially underestimated pipistrelle bat survival. Possible consequences of these findings for various aspects of life histories are discussed. [source] Effects of fat reserves on annual apparent survival of blackbirds Turdus merulaJOURNAL OF ANIMAL ECOLOGY, Issue 1 2003Mark W. Miller Summary 1Fat reserves are stored energy that may help birds survive periods of harsh winter weather. This hypothesis predicts that annual apparent survival is higher for birds with large fat reserves than for birds with few or no fat reserves in winter. 2Blackbirds (Turdus merula Linnaeus) were ringed in central Italy from 16 November to 20 February during 1990,2001. Fat scores were recorded for each bird. We used these capture,mark,recapture data for 1703 blackbirds to estimate the effect of large fat reserves on annual apparent survival, while controlling for transients, using computer programs surviv and mark. Probability of birds retaining large fat reserves, or retaining few fat reserves, over 2 successive years was also estimated. 3Birds with large fat reserves did not have higher estimated annual apparent survival than birds with few fat reserves (,,large= ,,few= 0·595, SE = 0·043), inconsistent with our prediction. No effects of age, sex or year were detected on annual apparent survival. Birds with few fat reserves in any given year tended to have few fat reserves the following year (, SE = 0·052). Birds with large fat reserves in any given year were unlikely to have large fat reserves the next year (, SE = 0·080). 4Large fat reserves may not increase annual survival of blackbirds wintering in central Italy. Winter weather in our study area may be too mild to effect survival. Alternatively, increased predation risk associated with large fat reserves may counteract any benefits of reduced starvation risk. [source] Wavelet analysis and the governing dynamics of a large-amplitude mesoscale gravity-wave event along the East Coast of the United StatesTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 577 2001Fuqing Zhang Abstract Detailed diagnostic analyses are performed upon a mesoscale numerical simulation of a well-observed gravity-wave event that occurred on 4 January 1994 along the East Coast of the United States. The value of using wavelet analysis to investigate the evolving gravity-wave structure and of using potential vorticity (PV) inversion to study the nature of the flow imbalance in the wave generation region is demonstrated. The cross-stream Lagrangian Rossby number, the residual in the nonlinear balance equation, and the unbalanced geopotential-height field obtained from PV inversion are each evaluated for their usefulness in diagnosing the flow imbalance. All of these fields showed clear evidence of strong imbalance associated with a middle-to-upper tropospheric jet streak, and tropopause fold upstream of the large-amplitude gravity wave several hours before the wave became apparent at the surface. Analysis indicates that a train of gravity waves was continuously generated by geostrophic adjustment in the exit region of the unbalanced upper-level jet streak as it approached the inflection axis in the height field immediately downstream of the maximum imbalance associated with the tropopause fold. A split front in the middle troposphere, characterized by the advance of the dry conveyor belt above the warm front, was overtaken by one of these propagating waves. During this merger process, a resonant interaction resulted, which promoted the rapid amplification and scale contraction of both the incipient wave (nonlinear wave development) and the split front (frontogenesis). The gravity wave and front aloft became inseparable following this merger. The situation became even more complex within a few hours as the vertical motion enhanced by this front-wave interaction acted upon a saturated, potentially unstable layer to produce elevated moist convection. An analysis of the temporal changes in the vertical profile of wave energy flux suggests that moist convective downdraughts efficiently transported the wave energy from the midlevels downward beneath the warm-front surface, where the wave became ducted. However, pure ducting was not sufficient for maintaining and amplifying the waves; rather, wave-CISK (Conditional Instability of the Second Kind) was crucial. This complex sequence of nonlinear interactions produced a long-lived, large-amplitude gravity wave that created hazardous winter weather and disrupted society over a broad and highly populated area. Although gravity waves with similar appearance to this large-amplitude wave of depression occasionally have been seen in other strong cyclogenesis cases involving a jet streak ahead of the upper-level trough axis, it is unknown whether other such events share this same sequence of interactions. [source] | ||||||||||