849 resultados para colonial breeding
Resumo:
The Ebro Delta holds a large seabird community, including a common tern (Sterna hirundo) local population of 3,085 pairs in 2000 which breeds scattered in several colonies. At El Canalot colony, 1,178 (1999) and 1,156 pairs (2000) of this species bred distributed in 32 and 38 sub-colonies respectively. These sub-colonies varied in size from 1 to 223 pairs and were placed near the main breeding colonies of yellow-legged gulls (Larus cachinnans) and Audouin´s gulls (L. audouinii), which are potential egg-predators of terns. We studied egg predation during 1999 (6 sub-colonies) and 2000 (27 sub-colonies). Overall, we found that 10.6% of the nests in 1999 and 16.7% in 2000 suffered partial or total egg predation, being total in 81.1% of the predatory events. Predation was significantly higher in small sub-colonies (< 11 pairs): 49.4% in 1999 and 75.5% in 2000. Only attacks from yellow-legged gulls were observed, and defence behaviour of terns was significantly more frequent against this gull species (40.5 hours of observation), suggesting that in most cases the egg predation recorded was due to this species. Probability of egg predation was significantly and negatively correlated with distance to the nearest yellow-legged gull sub-colony, although this relationship was no more significant after adjustment for sub-colony size. On the other hand, distance to the nearest Audouin´s gull sub-colony did not show any effect. Our results suggest that the impact of large gulls (at least yellow-legged gulls) upon smaller seabirds breeding in the area might be important, especially when they are breeding in small sub-colonies. Further studies are needed to analyse the general impact of large gulls upon the breeding populations of other colonial bird species in the area.
Resumo:
Réunissant quelques-uns des meilleurs experts français sur la question, le projet de cet ouvrage est de dresser un bilan des principales orientations historiographiques de l'histoire du sport. Cette réflexion complète la table ronde organisée lors du congrès du comité français des sciences historiques (Reims 2012). Elle s'interroge sur la spécificité d'un champ qui s'est développé en marge de l'Histoire en abordant un objet - le sport - qui traverse les cultures et les périodes, et entretient avec les registres politiques, sociaux, économiques, médiatiques, ou scientifiques des liens originaux. Appuyée sur des comparaisons européennes et nordaméricaines, elle suggère aussi des perspectives et de nouvelles pistes à investiguer. Cet ouvrage constitue une base de données précieuse pour les étudiants, doctorants, enseignants, chercheurs, archivistes et conservateurs et, plus largement, tout public averti et désireux de comprendre comment l'histoire a, jusqu'ici, questionné le phénomène sportif. Le lecteur y puisera des éléments conceptuels et des points d'appui historiographiques essentiels. Les grands débats du moment s'y reflètent : sport dans l'Antiquité, histoire de l'éducation physique, histoire économique du sport, histoire des techniques, des médias, du genre, ou encore histoire du sport en milieu colonial.
Resumo:
Data about breeding populations of birds in the Antarctica are rare and fragmented. Thus, information about the status of the breeding populations of Antarctic birds is crucial given the current scenario of climate change, which is particularly acute in Antarctica. This paper presents new information about the populations of the Antarctic tern Sterna vittata, the kelp gull Larus dominicanus, the southern giant petrel Macronectes giganteus, the Antarctic skua Catharacta antarctica lonnbergi, the chinstrap penguin Pygoscelis antarctica and the gentoo penguin Pygoscelis papua on Byers Peninsula (Livingston Island, South Shetland Islands). We used line transects counts to estimate both densities and numbers of nests of the different species. We estimate that there are 398.96 birds km-2 of southern giant petrels (2793 individuals), 62.4 birds km-2 of Antarctic tern (3746 individuals) and 269.1 birds km-2 of kelp gull (1884 individuals). Furthermore, we found 15 nests of Antarctic skua in 25 km2, from which we can estimate that 6091 birds must breed on Byers Peninsula. We also censused two colonies of gentoo penguins (3000 and 1200 pairs) and 50 pairs of chinstrap. Compared to previous estimates, gentoo penguins seem to have increased whereas chinstrap penguin have decreased. Finally, the populations of Antarctic tern, southern giant petrel and kelp gull have stabilized or slightly increased.
Resumo:
Feeding ecology and geographic location are 2 major factors influencing animal stable isotope signatures, but their relative contributions are poorly understood, which limits the usefulness of stable isotope analysis in the study of animal ecology. To improve our knowledge of the main sources of isotopic variability at sea, we determined δ15N and δ13C signatures in the first primary feather of adult birds from 11 Procellariiform species (n = 609) across 16 northeast Atlantic localities, from Cape Verde (20°N) to Iceland (60°N). Post-breeding areas (where the studied feather is thought to be grown) were determined using light-level geolocation for 6 of the 11 species. Isotopic variability was geographically unstructured within the mid-northeast Atlantic (Macaronesian archipelagos), but trophically structured according to species and regardless of the breeding location, presumably as a result of trophic segregation among species. Indeed, the interspecific isotopic overlap resulting from combining δ15N and δ13C signatures of seabirds was low, which suggests that most species exploited exclusive trophic resources consistently across their geographic range. Species breeding in north temperate regions (Iceland, Scotland and Northern Ireland) showed enriched δ15N compared to the same or similar species breeding in tropical and subtropical regions, suggesting some differences in baseline levels between these regions. The present study illustrates a noticeable trophic segregation of northeast Atlantic Procellariiformes. Our results show that the isotopic approach has limited applicability for the study of animal movements in the northeast Atlantic at a regional scale, but is potentially useful for the study of long-distance migrations between large marine systems
Resumo:
Coastal birds are an integral part of coastal ecosystems, which nowadays are subject to severe environmental pressures. Effective measures for the management and conservation of seabirds and their habitats call for insight into their population processes and the factors affecting their distribution and abundance. Central to national and international management and conservation measures is the availability of accurate data and information on bird populations, as well as on environmental trends and on measures taken to solve environmental problems. In this thesis I address different aspects of the occurrence, abundance, population trends and breeding success of waterbirds breeding on the Finnish coast of the Baltic Sea, and discuss the implications of the results for seabird monitoring, management and conservation. In addition, I assess the position and prospects of coastal bird monitoring data, in the processing and dissemination of biodiversity data and information in accordance with the Convention on Biological Diversity (CBD) and other national and international commitments. I show that important factors for seabird habitat selection are island area and elevation, water depth, shore openness, and the composition of island cover habitats. Habitat preferences are species-specific, with certain similarities within species groups. The occurrence of the colonial Arctic Tern (Sterna paradisaea) is partly affected by different habitat characteristics than its abundance. Using long-term bird monitoring data, I show that eutrophication and winter severity have reduced the populations of several Finnish seabird species. A major demographic factor through which environmental changes influence bird populations is breeding success. Breeding success can function as a more rapid indicator of sublethal environmental impacts than population trends, particularly for long-lived and slowbreeding species, and should therefore be included in coastal bird monitoring schemes. Among my target species, local breeding success can be shown to affect the populations of the Mallard (Anas platyrhynchos), the Eider (Somateria mollissima) and the Goosander (Mergus merganser) after a time lag corresponding to their species-specific recruitment age. For some of the target species, the number of individuals in late summer can be used as an easier and more cost-effective indicator of breeding success than brood counts. My results highlight that the interpretation and application of habitat and population studies require solid background knowledge of the ecology of the target species. In addition, the special characteristics of coastal birds, their habitats, and coastal bird monitoring data have to be considered in the assessment of their distribution and population trends. According to the results, the relationships between the occurrence, abundance and population trends of coastal birds and environmental factors can be quantitatively assessed using multivariate modelling and model selection. Spatial data sets widely available in Finland can be utilised in the calculation of several variables that are relevant to the habitat selection of Finnish coastal species. Concerning some habitat characteristics field work is still required, due to a lack of remotely sensed data or the low resolution of readily available data in relation to the fine scale of the habitat patches in the archipelago. While long-term data sets exist for water quality and weather, the lack of data concerning for instance the food resources of birds hampers more detailed studies of environmental effects on bird populations. Intensive studies of coastal bird species in different archipelago areas should be encouraged. The provision and free delivery of high-quality coastal data concerning bird populations and their habitats would greatly increase the capability of ecological modelling, as well as the management and conservation of coastal environments and communities. International initiatives that promote open spatial data infrastructures and sharing are therefore highly regarded. To function effectively, international information networks, such as the biodiversity Clearing House Mechanism (CHM) under the CBD, need to be rooted at regional and local levels. Attention should also be paid to the processing of data for higher levels of the information hierarchy, so that data are synthesized and developed into high-quality knowledge applicable to management and conservation.
Resumo:
Majolica pottery was the most characteristic tableware produced in Europe during the Medieval and Renaissance periods. Because of the prestige and importance attributed to this ware, Spanish majolica was imported in vast quantities into the Americas during the Spanish Colonial period. A study of Spanish majolica was conducted on a set of 186 samples from the 10 primary majolica production centres on the Iberian Peninsula and 22 sherds from two early colonial archaeological sites on the Canary Islands. The samples were analysed by neutron activation analysis (NAA), and the resulting data were interpreted using an array of multivariate statistical approaches. Our results show a clear discrimination between different production centres, allowing a reliable provenance attribution of the sherds from the Canary Islands.
Resumo:
This article discusses the processes inherent in the production of salpeter in Colonial Brazil. In the main, the texts seen here present recipes accompanied by chemical explanations of the processes which denote a knowledge of science at the time. Various difficulties confronting the authors, however, prevented an effective contribution to the development of techniques for the production of salpeter. Consequenttly, at the end of the Nineteenth Century, Brazilian rulers are still facing many problems to obtain this precious material.
Resumo:
Within the scope of the TECNOLONIAL (HAR2008-02834/HIST) project, an archaeologi- cal and archaeometric research is being conduct- ed in order to clarify and systematize transport jars production in the Iberian peninsula and their distribution abroad, especially to the Americas, from the 15th to the 17th century. The production centre of Seville, in the Crown of Castile, produced large glazed and unglazed transport jars, called botijas, which were mainly devoted to the Atlantic trade network. The pres- ent study accounts for the first results obtained from an initial sample of 34 transport jars dated around the 15th-16th centuries from the produc- tion centre of Seville and the reception site of Santa María de la Antigua del Darién (gulf of Urabá, Colombia). This latter site is especially significant since it was the first Spanish founda- tion (1510) in continental America that obtained the title of town, and was the seat for the Governor of the new region called Castilla de Oro, as well as for the first diocese. All individuals were analyzed by means of x-ray fluorescence and diffraction analyses and then compared with the majolica production database from Seville. The results enabled us to define the first refer- ence groups for such modern transport jars, and to get a first insight into the jars coming to the Americas in the early 16th century whose prove- nance can be linked to Seville, but not Triana.
Resumo:
Stable carbon and nitrogen isotopes in skin and bone of South American sea lions from Brazil and Uruguay were analysed to test the hypothesis that trophic overlap between the sexes is lower during the pre-breeding season than throughout the rest of the year. The isotopic values of skin and bone were used to infer the trophic relationships between the sexes during the pre-breeding period and year round, respectively. Prey species were also analysed to establish a baseline necessary for interpreting the stable isotope ratios of skin and bone. Standard ellipse areas, estimated using Bayesian inference in the SIBER routine of the SIAR package in R, suggested that males and females used a wide diversity of foraging strategies throughout the year and that no differences existed between the sexes. However, the diversity of foraging strategies was largely reduced during the pre-breeding period, with all the individuals of each sex adopting similar strategies, but with the two sexes differing considerably in stable isotope values and the ellipse areas of males and females not overlapping at all. Nevertheless, the results revealed a general increase in the consumption of pelagic prey by both sexes during the pre-breeding period. The progressive crowding of individuals in the areas surrounding the breeding rookeries during the pre-breeding period could lead to an increase in the local population density, which could explain the above reported changes.
Resumo:
Organic residue analysis of archaeological potsherds is a well-established method for determining the uses of European and North American pottery vessels. In the present work we assess if the organic residues identified in Brazilian potsherd extracts are related to commodity processes (e.g. cooking or surface treatment) or to other non-archaeological sources, using as a model potsherds recovered from the Rio do Meio site (Santa Catarina Island). The potsherd extracts are dominated by saturated fatty acids (Ac16:0, with lower abundances of Ac14:0 and Ac18:0). Our studies provide evidence that the organic residues preserved in the Brazilian archeological potsherds are related to foodstuffs and surface treatment processes of the pottery vessels.
Resumo:
European naturalists explored Brazil in long scientific expeditions and published accounts that make up a rich and still largely untapped historiographic source for the understanding of the history of chemistry. The production of indigo dye, the manufacture of limestone, extraction and purification of saltpeter and the production of salt are discussed. Lime was used to whitewash walls and, mixed with whale oil, as cement to glue stones in buildings of the colonial period. It was prepared by burning seashells in specifically designed ovens. Saltpeter was produced by reacting naturally occurring calcium and magnesium nitrate with potassium-rich wood ashes to yield KNO3. NaCl was obtained by evaporating seawater under the sun. Indigo, a native plant, was cultivated and processed to produce the renowned dye, which was exported to Europe.