Common Buzzards wintering strategies as an effect of weather conditions and geographic barriers

AimMigration is a constantly changing adaptation due to the climate condition evolution. The struggle for surviving during harsh winter season is different across Europe, being more complex toward the inner parts of the continent. The current approach explores the Common Buzzard number variation during the cold season and the climatic predictors of birds of prey wintering movements in relation to the possible influences of the Carpathian Mountains, which may act as a geographical barrier providing shelter from cold air outbreak from north and northeast of the continent.LocationRomania (45°N25°E).TaxonBirds of Prey.MethodsWe applied a GLMM to investigate the relation between continental and local climatic factors with the number of Common Buzzard observations in two regions. The first region is located inside the Carpathian Arch and the other one outside, east of this large mountains chain.ResultsThe Common Buzzard numbers wintering Eastern from the Carpathian Mountains are highly influenced by AO (Z = 2.87, p < .05%), while those wintering western are influenced by NAO (Z = 2.17, p < .05%). This is the first proof of separating influences for biodiversity of AO and NAO at continental scale, outlining the influence limit placed over the Eastern Carpathian Mountains.Main conclusionsThe Carpathian Mountains act like a geographic barrier, separating the wintering Common Buzzard populations from both sides of the mountain range. While the high number of individuals in Moldova is related to their eastern and northeastern Europe origins, in Transylvania the large number of individuals observed is related to the more sheltered characteristics of the region attracting individuals from central Europe. Also, since Transylvania region is well sheltered during cold air outbreak, it represents a more favorable region for wintering. From this point of view, we can consider that the Carpathian Mountains are a geographic barrier for wintering birds of prey.     

不同天气条件下青头潜鸭越冬期行为的响应模式

2018年11—12月在河南民权国家湿地公园,采用定点观察法、扫描取样法对越冬青头潜鸭在不同天气条件下的行为响应模式进行研究。结果表明: 在晴天,静息、飞行、运动是青头潜鸭越冬期的优势行为(65.5%),觅食、修整是次要行为(31.9%);行为节律表现为上午觅食、中午静息、下午觅食修整;飞行通常发生在觅食高峰前,运动行为多与其他行为相伴,其时间分配与觅食呈正响应,与静息呈负响应。相较于晴天,阴雨天青头潜鸭增加了对静息和觅食的时间分配,静息、觅食和运动为阴雨天的主要行为(76.5%),修整、飞行为次要行为(20.3%);觅食和静息的高峰时段后移,傍晚时达到高峰,飞行和修整时间显著减少。与晴天相比,雾霭天青头潜鸭静息、觅食、运动和修整的时间分配增加,飞行行为减少;觅食高峰后移至中午和下午,静息高峰后移至下午;静息、运动和觅食为雾霭天的优势行为(70.6%),修整和飞行为次要行为(27.5%)。研究表明,不同天气条件下,民权湿地公园青头潜鸭的越冬期行为在时间分配、行为节律、优势行为方面存在一定的响应;阴雨天和雾霭天青头潜鸭会分配更多的静息和觅食时间,并通过增加能量摄入和减少耗能行为应对恶劣天气。     

Potential use of weather radar to study movements of wintering waterfowl

To protect and restore wintering waterfowl habitat, managers require knowledge of routine wintering waterfowl movements and habitat use. During preliminary screening of Doppler weather radar data we observed biological movements consistent with routine foraging flights of wintering waterfowl known to occur near Lacassine National Wildlife Refuge (NWR), Louisiana. During the winters of 2004–2005 and 2005–2006, we conducted field surveys to identify the source of the radar echoes emanating from Lacassine NWR. We compared field data to weather radar reflectivity data. Spatial and temporal patterns consistent with foraging flight movements appeared in weather radar data on all dates of field surveys. Dabbling ducks were the dominant taxa flying within the radar beam during the foraging flight period. Using linear regression, we found a positive log-linear relationship between average radar reflectivity (Z) and number of birds detected over the study area (P < 0.001, r² = 0.62, n = 40). Ground observations and the statistically significant relationship between radar data and field data confirm that Doppler weather radar recorded the foraging flights of dabbling ducks. Weather radars may be effective tools for wintering waterfowl management because they provide broad-scale views of both diurnal and nocturnal movements. In addition, an extensive data archive enables the study of wintering waterfowl response to habitat loss, agricultural practices, wetland restoration, and other research questions that require multiple years of data. © 2011 The Wildlife Society.     

Slug activity in relation to weather

Multiple regression analysis was carried out on the effect of certain meteorological factors on the numbers of slugs attracted by metaldehyde and bran biscuits at Cardiff in the autumn months. By far the greatest reduction in the variance in numbers of slugs attracted each morning was achieved by taking out the effects of two factors: (1) the length of time the biscuits had been exposed, and (2) the average night air temperature. The percentage relative humidity considered alone had little effect on the variance. Regression coefficients, at each site, for factors (I) and (2) on slug numbers appeared to be in close agreement and it is suggested that these figures would serve as a measure of slug activity. Arion hortensis behaved differently from the other species studied, its day-to-day variation in numbers not being tied so closely to the meteorological factors examined.
Methods of assessing slug numbers in the field usually rely on the animals' activity. Barnes & Weil (1944) made direct counts on the slugs observable in half-hourly periods, and Thomas (1944) based estimates of the number attracted to metaldehyde and bran biscuits overnight; Duthoit (1961) used baits of wheat seed in making weekly estimates. Measures of activity, however, may be less directly related to the actual population present than to day-to-day climatological variations. The aim of the work described below was to find if it was possible to arrive at more reproducible population estimates by using standard slug biscuits, and allowing for the effect of some of the meteorological variables.     

Reconstruction of pre-monsoon weather conditions in northwestern Thailand from the tree-ring widths of Pinus merkusii and Pinus kesiya

Two pine species, Pinus merkusii and Pinus kesiya, native in Thailand were studied for their potential to reconstruct past weather conditions from their tree rings. Altogether, cores from 209 Merkus pines and from 205 Khasi pines were sampled at 16 sites. Standard methods were applied to assemble tree-ring chronologies for each site and tree species. The longest site chronology of Merkus pine and Khasi pine covered 314 and 183 years, respectively. Principal component analysis (PCA) illustrated a close clustering of all, except two, site chronologies on the PC1 axis, indicating a strong signal common for both pine species throughout NW Thailand. However, along the PC2 axis, there was a distinct separation between the Merkus pine and the Khasi pine site chronologies, which was possibly due to the species-specific differences in site altitudes. Simple correlations between the PC1 time series and a regionalized climate data set showed a highly negative association with temperature during the pre-monsoon period from March to May. Since, pre-monsoon temperature and rainfall were negatively correlated with each other, we used the PC1 as a direct proxy for pre-monsoon weather conditions (warm/dry vs. cool/wet) back to 1834 AD.     

The annual variation of asthma in Brisbane: Its relation to the weather

A study has been made of the annual incidence of asthma in Brisbane for 7 years in relation to the weather. The element most closely associated with asthma was rainfall. There was a minor, independent association with temperature. The association of asthma with rain and warmth, which promote the growth of vegetation, supports the suggestion arising from the seasonal study of asthma that vegetation may be an important source of allergens.

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Zusammenfassung Die Beziehung zwischen dem Wetter und der Häufigkeit von Asthma in Brisbane während 7 Jahren wurde untersucht. Unter den meteorologischen Elementen ergab sich die engste Beziehung zwischen Asthmahäufigkeit und Niederschlägen. Eine geringere, unabhängige Beziehung bestand mit der Temperatur. Die Verbindung von Asthma mit Niederschlägen und Wärme stützt die Vermutung, dass die Vegetation eine wichtige Allergenquelle ist.

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Resume On a étudié durant 7 années la relation existant entre le temps et la fréquence des crises d'asthme à Brisbane. Parmi les éléments météorologiques examinés, celui qui donna la plus étroite relation est la précipitation.Une relation indépendante, moindre il est vrai, existe également avec la température.L'étroite relation entre les crises d'asthme d'une part, les précipitations et la chaleur d'autre part renforce l'hypothèse que la végétation est la principale source des principes allergènes.

     

Flight activity of adult stoneflies in relation to weather

Abstract. 1. Dispersal of adult aquatic insects between streams may have important consequences for local and regional population dynamics, but little is known about how dispersal is affected by weather conditions.
2. The influence of meteorological variables on flight activity of adult stoneflies (Plecoptera: Leuctridae, Nemouridae, and Chloroperlidae) was investigated using Malaise traps adjacent to three upland streams in the Plynlimon area of mid Wales, U.K.
3. Numbers of adult stoneflies captured weekly in the traps were related positively to air temperature and related negatively to wind speed. Meteorological conditions during daylight showed stronger relationships with flight activity than did conditions at night.
4. There was inter-site variation in the strength of weather effects on stonefly flight. Wind speed was significant at only one site, which had higher average wind speed than the other sites.
5. Annual variation in weather conditions during adult flight periods may result in varying extent of dispersal between sites, influencing community dynamics over a wide area.     

Changes in the flocking behaviour of wintering English titmice with time,weather and supplementary food

Over the course of one winter, the food supply of birds living in a deciduous woodland in southern England was supplemented and unsupplemented during alternating periods. In the presence of substantial predation pressure from hawks, the sociality of blue tits, Parus caeruleus, and great tits, P. major, showed significant partial correlations with several weather and temporal factors when the woodland was unsupplemented. Such correlations between social behaviour and abiotic factors diminished significantly when the birds had access to extra food. Blue tits and great tits without access to supplemental food flocked significantly more often with other species while foraging than when they were food-supplemented. Long-tailed tits, Aegithalos caudatus, ignored the artificial food and foraged in mixed-species flocks to the same extent in both unsupplemented and food-supplemented periods. Results disprove the hypothesis that mixed-species foraging groups are caused by increased predation protection alone, and they support the hypotheses that mixed-species foraging groups are caused by increased foraging efficiency alone or by a combination of increased foraging efficiency and increased protection from predators.     

Distribution patterns of wintering sea ducks in relation to the North Atlantic Oscillation and local environmental characteristics

Twelve species of North American sea ducks (Tribe Mergini) winter off the eastern coast of the United States and Canada. Yet, despite their seasonal proximity to urbanized areas in this region, there is limited information on patterns of wintering sea duck habitat use. It is difficult to gather information on sea ducks because of the relative inaccessibility of their offshore locations, their high degree of mobility, and their aggregated distributions. To characterize environmental conditions that affect wintering distributions, as well as their geographic ranges, we analyzed count data on five species of sea ducks (black scoters Melanitta nigra americana, surf scoters M. perspicillata, white-winged scoters M. fusca, common eiders Somateria mollissima, and long-tailed ducks Clangula hyemalis) that were collected during the Atlantic Flyway Sea Duck Survey for ten years starting in the early 1990s. We modeled count data for each species within ten-nautical-mile linear survey segments using a zero-inflated negative binomial model that included four local-scale habitat covariates (sea surface temperature, mean bottom depth, maximum bottom slope, and a variable to indicate if the segment was in a bay or not), one broad-scale covariate (the North Atlantic Oscillation), and a temporal correlation component. Our results indicate that species distributions have strong latitudinal gradients and consistency in local habitat use. The North Atlantic Oscillation was the only environmental covariate that had a significant (but variable) effect on the expected count for all five species, suggesting that broad-scale climatic conditions may be directly or indirectly important to the distributions of wintering sea ducks. Our results provide critical information on species–habitat associations, elucidate the complicated relationship between the North Atlantic Oscillation, sea surface temperature, and local sea duck abundances, and should be useful in assessing the impacts of climate change on seabirds.     

Variable effects of the Hen Flea Ceratophyllus gallinae on the breeding success of the Great Tit Parus major in relation to weather conditions

We investigated the effect of an ectoparasite, the Hen Flea Ceratophyllus gallinae (Siphonaptera), on the reproductive success of the Great Tit Parus major, a hole-nesting passerine bird. Parasite levels of cleaned nesting boxes were experimentally manipulated during the egg-laying period of the birds either by spraying nests with pyrethrin or by introducing c. 100 adult fleas, while other nests were left as controls. Only in 2 out of 5 years did hen fleas significantly affect reproductive success. Nestlings from parasitized nests showed reduced body-mass, tarsus-length and condition, whereas wing-length did not differ between nestlings reared with or without fleas. The impact of the fleas on the growth performance of host nestlings was more noticeable in years with lower temperatures and higher precipitation.     

Climatic responses in spring migration of boreal and arctic birds in relation to wintering area and taxonomy

Large‐scale climate fluctuations, such as the North Atlantic Oscillation (NAO), have a marked effect on the timing of spring migration of birds. It has however been suggested that long‐distance migrants wintering in Africa could respond less to NAO than short‐distance migrants wintering in Europe, making them more vulnerable to climatic changes. We studied whether migratory boreal and arctic bird species returning from different wintering areas show differences in responses to the NAO in the timing of their spring migration. We used data on 75 species from two bird observatories in northern Europe (60°N). By extending the examination to the whole distribution of spring migration and to a taxonomically diverse set of birds, we aimed at finding general patterns of the effects of climate fluctuation on the timing of avian migration. Most species arrived earlier after winters with high NAO index. The degree of NAO‐response diminished with the phase of migration: the early part of a species’ migratory population responded more strongly than the later part. Early phase waterfowl responded strongest to NAO, but in later phases their response faded to non‐significant. This pattern may be related to winter severity and/or ice conditions in the Baltic. In the two other groups, gulls and waders and passerines, all phases of migration responded to NAO and fading with phase was non‐significant. The difference between waterfowl and other groups may be related to differences between the phenological development of their respective macrohabitats. Wintering area affected the strength of NAO response in a complicated way. On average medium distance migrants responded most strongly, followed by short‐distance migrants and partial migrants. Our results concerning the response of long‐distance migrants were difficult to interpret: there is an overall weak yet statistically significant effect, but patterns with phase of migration need further study. Our results highlight the importance of examining the whole distribution of migration and warrant the use of data sets from several sampling sites when studying climatic effects on the timing of avian life‐history events.