74 resultados para Wild birds

em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast


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Since 1989, a red kite Milvus milvus reintroduction programme has been underway in the United Kingdom, with 4-6 week old nestlings brought into captivity and held for 6-8 weeks before reintroduction. As scavengers, red kites may consume unretrieved game, and ingest shot or lead (Pb) fragments in their prey's flesh. We evaluated exposure to Pb in captive and wild red kites by taking blood samples from 125 captive young red kites prior to release, through analysing 264 pellets (regurgitated by wild birds) collected from under a roost site, and analysing Pb concentrations in livers and/or bones of 87 red kites found dead between 1995 and 2003. Lead isotope analyses of livers were also conducted in an effort to identify Pb exposure routes. Forty-six (36.8%) kites sampled prior to release had elevated blood Pb concentrations (201-3340 microg l(-1)). The source of this Pb was probably small fragments of lead ammunition in the carcasses of birds or mammals either fed to the nestlings by their parents or, more likely, subsequently whilst in captivity. Once released, kites were also exposed to lead shot in their food, and a minimum of 1.5-2.3% of regurgitated pellets contained Pb gunshot. Seven of 44 red kites found dead or that were captured sick and died within a few days had elevated (>6 mg kg(-1) dry weight [d.w.]) liver Pb concentrations, and six of these (14%) had concentrations of >15 mg kg(-1) d.w., compatible with fatal Pb poisoning. Post-mortem analyses indicated that two of these birds had died of other causes (poisoning by rodenticide and a banned agricultural pesticide); the remaining four (9%) probably died of Pb poisoning. Bone samples from 86 red kites showed a skewed distribution of Pb concentration, and 18 samples (21%) had Pb concentrations >20 mg kg(-1) d.w., indicating elevated exposure to Pb at some stage in the birds' life. Lead isotopic signatures (Pb (208/206); Pb (206/207)) in liver samples of the majority of kites were compatible with those found in lead shot extracted from regurgitated pellets. Lead isotope ratios found in the livers of kites with very low Pb concentrations were distinct from UK petrol Pb isotopic signatures, indicating that birds were exposed to little residual petrol Pb. We conclude that the primary source of Pb to which red kites are exposed is lead ammunition (shotgun pellets or rifle bullets), or fragments thereof, in their food sources; in some cases exposure appears sufficient to be fatal. We make recommendations to reduce Pb poisoning in both captive and wild red kites and other scavenging species.

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For many years, orientation in migratory birds has primarily been studied in the laboratory. Although a laboratory-based setting enables greater control over environmental cues, the laboratory-based findings must be confirmed in the wild in free-flying birds to be able to fully understand how birds orient during migration. Despite the difficulties associated with following free-flying birds over long distances, a number of possibilities currently exist for tracking the long distance, sometimes even globe-spanning, journeys undertaken by migrating birds. Birds fitted with radio transmitters can either be located from the ground or from aircraft (conventional tracking), or from space. Alternatively, positional information obtained by onboard equipment (e.g., GPS units) can be transmitted to receivers in space. Use of these tracking methods has provided a wealth of information on migratory behaviors that are otherwise very difficult to study. Here, we focus on the progress in understanding certain components of the migration-orientation system. Comparably exciting results can be expected in the future from tracking free-flying migrants in the wild. Use of orientation cues has been studied in migrating raptors (satellite telemetry) and thrushes (conventional telemetry), highlighting that findings in the natural setting may not always be as expected on the basis of cage-experiments. Furthermore, field tracking methods combined with experimental approaches have finally allowed for an extension of the paradigmatic displacement experiments performed by Perdeck in 1958 on the short-distance, social migrant, the starling, to long-distance migrating storks and long-distance, non-socially migrating passerines. Results from these studies provide fundamental insights into the nature of the migratory orientation system that enables experienced birds to navigate and guide inexperienced, young birds to their species-specific winter grounds.

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Lead is a highly toxic metal known to be an important cause of morbidity and mortality in waterbirds and terrestrial birds worldwide. The risk to birds of poisoning from lead has resulted in the introduction of legislation in many countries, such as UK restrictions on the use of lead in angling weights and lead gunshot. In this study, we examined data on current and historical trends in lead poisoning in British waterbirds and related these to the introduction of legislation restricting the use of lead. Our results indicate that lead poisoning has continued to affect a wide range of British waterbirds long after legal restrictions were introduced. Elevated levels of lead (i.e. > 20.0 mu g/dL) were found in the blood of 34 % (n = 285) of waterbirds tested at four sites in Britain during the 2010/2011 winter and accounted for the deaths of at least 10.6 % (n = 2,365) of waterbirds recovered across Britain between 1971 and 2010 and 8.1 % (n = 1,051) between 2000 and 2010, with lead gunshot being the most likely source of poisoning. The proportion of birds dying from lead poisoning in England did not vary significantly after the introduction of legislation, accounting for 13.7 % of non-infectious causes of death between 1971 and 1987 (n = 204), 20.8 % (n = 360) between 1988 and 1999 and 11.8 % (n = 423) between 2000 and 2010, despite a significant change in lead-related mortality in mute swans found during the same time period, 25 % (n = 12) between 1971 and 1987, 4.6 % (n = 65) between 1988 and 1999 and 2 % (n = 100) between 2000 and 2010. Existing legislation needs review and extension to ensure the delivery of international commitments and a broad-scale transition to the use of non-toxic shot and angling materials in all environments.

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The high level of escapes from Atlantic salmon farms, up to two million fishes per year in the North Atlantic, has raised concern about the potential impact on wild populations. We report on a twogeneration experiment examining the estimated lifetime successes, relative to wild natives, of farm, F1 and F2 hybrids and BC1 backcrosses to wild and farm salmon. Offspring of farm and hybrids (i.e. all F1 , F2 and BC1 groups) showed reduced survival compared with wild salmon but grew faster as juveniles and displaced wild parr, which as a group were significantly smaller. Where suitable habitat for these emigrant parr is absent, this competition would result in reduced wild smolt production. In the experimental conditions, where emigrants survived downstream, the relative estimated lifetime success ranged from 2% (farm) to 89% (BC1 wild) of that of wild salmon, indicating additive genetic variation for survival . Wild salmon primarily returned to fresh water after one sea winter (1SW) but farm and hybrids produced proportionately more 2SW salmon. However, lower overall survival means that this would result in reduced recruitment despite increased 2SW fecundity. We thus demonstrate that interaction of farm with wild salmon results in lowered fitness, with repeated escapes causing cumulative fitness depression and potentially an extinction vortex in vulnerable populations.

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This article examines the travel writings and medical work in India of Lady Hariot Dufferin, Vicereine of India between 1884 and 1888. Lady Dufferin accompanied her husband, the Viceroy Lord Dufferin, through various social and political engagements in India, and carved her own niche in colonial and postcolonial history as a pioneer in the medical training of women in India. The article examines her travel writings on India and explores the nature of her complicity in the Raj, as well as the gendered nature of the separate public role she created for herself in relation to her 'zenana work' in providing medical care for the women of India. The author suggests that, through her work, Lady Dufferin challenges and extends the theoretical paradigms of postcolonialist and feminist critiques of empire.

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With the advent of the United Nations Convention on the Rights of the Child (CRC), there is an increasing requirement that schools ensure children and young people's views are voiced, listened to and taken seriously on matters of significance. Encouraging these shifts by law is one thing; changing the culture in schools is another. For a significant proportion of schools, actively engaging students' voices on how they experience education poses a significant challenge and crucial gaps may exist between the rhetoric espoused and a school's readiness for genuine student involvement. This ethnographic study illuminates tensions that persist between headteachers' espoused views of how students are valued and students' creative images of their actual post-primary schooling experience. If cultures of schooling are to nurture the true spirit of democratic pupil participation implied by changes in the law, there is a need to develop genuine processes of student engagement in which students and staff can collaborate towards greater shared understandings of a school's priorities.

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We describe here a method of assessment for students. A number of short-comings of traditional assessment methods, especially essays and examinations, are discussed and an alternative assessment method, the student project, is suggested. The method aims not just to overcome the short-comings of more traditional methods, but also to provide over-worked and under-resourced academics with viable primary data for socio-legal research work. Limitations to the method are discussed, with proposals for minimising the impact of these limitations. The whole �student project� approach is also discussed with reference to the Quality Assurance Agency benchmark standards for law degrees, standards which are expected of all institutions in the UK.

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