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144 result(s) for "Sea eagle"
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Semi‐automated detection of eagle nests: an application of very high‐resolution image data and advanced image analyses to wildlife surveys
Very high‐resolution (VHR) image data, including from unmanned aerial vehicle (UAV) platforms, are increasingly acquired for wildlife surveys. Animals or structures they build (e.g. nests) can be photointerpreted from these images, however, automated detection is required for more efficient surveys. We developed semi‐automated analyses to map white‐bellied sea eagle (Haliaeetus leucogaster) nests in VHR aerial photographs of the Houtman Abrolhos Islands, Western Australia, an important breeding site for many seabird species. Nest detection is complicated by high environmental heterogeneity at the scale of nests (~1–2 m), the presence of many features that resemble nests and the variability of nest size, shape and context. Finally, the rarity of nests limits the availability of training data. These challenges are not unique to wildlife surveys and we show how they can be overcome by an innovative integration of object‐based image analyses (OBIA) and the powerful machine learning one‐class classifier Maxent. Maxent classifications using features characterizing object texture, geometry and neighborhood, along with limited object color information, successfully identified over 90% of high quality nests (most weathered and unusually shaped nests were also detected, but at a slightly lower rate) and labeled <2% of objects as candidate nests. Although this overestimates the occurrence of nests, the results can be visually screened to rule out all but the most likely nests in a process that is simpler and more efficient than manual photointerpretation of the full image. Our study shows that semi‐automated image analyses for wildlife surveys are achievable. Furthermore, the developed strategies have broad relevance to image processing applications that seek to detect rare features differing only subtly from a heterogeneous background, including remote sensing of archeological remains. We also highlight solutions to maximize the use of imperfect or uncalibrated image data, such as some UAV‐based imagery and the growing body of VHR imagery available in Google Earth and other virtual globes. Very high‐resolution image data are increasingly acquired for wildlife surveys. It has been difficult to detect nests of the white‐bellied sea eagle (Haliaeetus leucogaster) from image data, but these challenges were overcome by an innovative integration of object‐based image analyses (OBIA) and the powerful machine learning one‐class classifier Maxent. The strategies developed have broad relevance to image processing applications that seek to detect rare features differing only subtly from a heterogeneous background, and can be applied to rigorous analyses of uncalibrated image data, for instance available in virtual globes.
conflict management tool for conservation agencies
Growing pressure on natural resources is leading to more conservation conflicts. Governments and their statutory agencies devote increasing financial and human resources to this subject, but tend to adopt reactive, ad hoc approaches to management. We combined theory and empirical data about five conservation conflicts in a transdisciplinary collaboration to co‐develop a novel decision‐making tool. This tool uses a systematic stepwise approach with six distinct decision stages: (i) establishing whether there is a conflict or an impact; (ii) understanding the context of the conflict, including the stakeholders affected; (iii) developing shared understanding of the conflict and goals; (iv) building a consensus on how to reach the goals; (v) implementing measures; and (vi) monitoring the outcomes. Policy implications. We argue this new tool has wide applicability and democratic legitimacy and offers an exciting and practical approach to improve the management of conservation conflicts.
Avian raptors are indicator species and victims of high pathogenicity avian influenza virus HPAIV H5N1 (clade 2.3.4.4b) in Germany
Transition of highly pathogenic clade 2.3.4.4b H5 avian influenza virus (HPAIV) from epizootic to enzootic status in Northern European countries was associated with severe losses and even mass mortalities among various wild bird species. Both avian and mammalian raptors hunting infected debilitated birds or scavenging on virus-contaminated avian carcasses contracted HPAIV infection. This precarious pathogen-prey-predator relation further worsened when in 2021 and 2022 outbreaks in Germany overlapped with the hatching season of avian raptor species. Retro- and prospective surveillance revealed avian raptors as important indicators of HPAIV and its genetic diversity on the one hand. On the other hand, their role as victims of HPAIV is stipulated. The first case of an HPAIV H5N1-related death of a white-tailed sea eagle ( Haliaeetus albicilla; WTSE) hatch in Germany, 2021, followed by several such cases in 2022, and a low overall seropositivity rate of 5.0–7.9% among WTSE nestlings, raised fears of a serious negative impact on reproduction rates of WTSEs and other birds of prey when HPAIV becomes enzootic in an ecosystem. However, comparably stable breeding success of WTSE in the study area in 2022 and a potentially evolving natural immunity raises hope for a less severe long-term impact.
White-Tailed Sea Eagle (Haliaeetus albicilla) Die-Off Due to Infection with Highly Pathogenic Avian Influenza Virus, Subtype H5N8, in Germany
In contrast to previous incursions of highly pathogenic avian influenza (HPAIV) H5 viruses, H5N8 clade 2.3.4.4b viruses caused numerous cases of lethal infections in white-tailed sea eagles (Haliaeetus albicilla) affecting mainly young eagles (younger than five years of age) in Germany during winter 2016/2017. Until April 2017, 17 HPAIV H5N8-positive white-tailed sea eagles had been detected (three found alive and 14 carcasses) by real-time RT-PCR and partial nucleotide sequence analyses. Severe neurological clinical signs were noticed which were corroborated by immunohistopathology revealing mild to moderate, oligo- to multifocal necrotizing virus-induced polioencephalitis. Lethal lead (Pb) concentrations, a main factor of mortality in sea eagles in previous years, could be ruled out by atomic absorption spectrometry. HPAIV H5 clade 2.3.4.4b reportedly is the first highly pathogenic influenza virus known to induce fatal disease in European white-tailed see eagles. This virus strain may become a new health threat to a highly protected species across its distribution range in Eurasia. Positive cloacal swabs suggest that eagles can spread the virus with their faeces.
Parental Hacking—An Alternative Reintroduction Method for the White-Tailed Sea Eagle (Haliaeetus albicilla)
In an age of rewilding and dramatic declines in biodiversity, we are developing a new way to reintroduce raptors: parental hacking. The principle behind it is similar to traditional hacking, where the birds are released without contact with adult conspecifics. In parental hacking, our method, the parents feed their own offspring until the end of the post-fledgling dependency period. Our programme aims to reintroduce the white-tailed sea eagle (Haliaeetus albicilla) to the Upper Rhône Basin in France. It started in 2022 and will continue until 2030, with the release of 80 young eagles. We describe the method used in 2022, followed by the improvements made in 2023, and finally compare the two years. The young eagles were raised in aviaries at the reintroduction site by their captive-born parents in the Aigles du Léman Park (Haute-Savoie, France). In 2022, two young females and two young males were released as soon as they were able to fly at the age of three months, but they often ended up on the ground due to a lack of flying ability and attacks from wild black kites (Milvus migrans) defending their territory. Therefore, the young eagles were returned to their parents’ aviary before being released a second time at five months in August 2022. One month after release, one male was already 50 km from the reintroduction site, while the other three stayed close to the park. In 2023, five young females and five young males were released at five months. This came after four weeks in a large training aviary to learn how to fly, perch, and fish. The behaviour of the young eagles after release varied greatly between individuals. Overall, 4 out of 10 young eagles travelled long distances and did not return to the reintroduction site to feed within a month, while the other 6 chose to stay close (within 20 km) to the reintroduction site.
Case report: secondary poisoning in a white-tailed sea eagle caused by carbofuran
A juvenile white-tailed sea eagle found alive on an island in the Baltic Sea died due to a secondary carbofuran poisoning. At necropsy, parts of a raven were found in the eagle’s gizzard, including the stomach containing seeds with carbofuran residues. Illegal persecution using poisoned baits often kill scavenging birds of prey. However, secondary poisoning of birds of prey has been rarely reported in Europe. The report aims to raise awareness to include toxicological analysis in forensic examinations in cases of otherwise healthy and well-feed birds found dead with no obvious cause of mortality.
Leadership and management influences the outcome of wildlife reintroduction programs: findings from the Sea Eagle Recovery Project
Wildlife reintroductions and translocations are statistically unlikely to succeed. Nevertheless, they remain a critical part of conservation because they are the only way to actively restore a species into a habitat from which it has been extirpated. Past efforts to improve these practices have attributed the low success rate to failures in the biological knowledge (e.g., ignorance of social behavior, poor release site selection), or to the inherent challenges of reinstating a species into an area where threats have already driven it to local extinction. Such research presumes that the only way to improve reintroduction outcomes is through improved biological knowledge. This emphasis on biological solutions may have caused researchers to overlook the potential influence of other factors on reintroduction outcomes. I employed a grounded theory approach to study the leadership and management of a successful reintroduction program (the Sea Eagle Recovery Project in Scotland, UK) and identify four critical managerial elements that I theorize may have contributed to the successful outcome of this 50-year reintroduction. These elements are: 1. Leadership & Management: Small, dedicated team of accessible experts who provide strong political and scientific advocacy (\"champions\") for the project. 2. Hierarchy & Autonomy: Hierarchical management structure that nevertheless permits high individual autonomy. 3. Goals & Evaluation: Formalized goal-setting and regular, critical evaluation of the project's progress toward those goals. 4. Adaptive Public Relations: Adaptive outreach campaigns that are open, transparent, inclusive (esp. linguistically), and culturally relevant.
卫星跟踪白尾海雕迁徙路线和栖息地利用
白尾海雕(Haliaeetus albicilla)为顶级捕食者,国家一级重点保护野生动物,2023年2月—2024年4月,采用卫星跟踪技术对1只北京野放的白尾海雕活动轨迹进行追踪,研究其迁徙路线、日活动节律、活动区面积和栖息地利用情况。结果表明:(1)白尾海雕在俄罗斯西伯利亚北部度夏,在蒙古国东部东方省越冬,春季迁徙速度(98.49 km/d)比秋季迁徙速度(106.09 km/d)慢,春季迁徙距离6 106.21 km,历时 62 d,秋季迁徙距离为4 137.63 km,历时39 d;(2)白尾海雕为典型昼间迁徙猛禽,每日迁徙开始于05:00—06:00,停止于18:00—19:00,迁徙时长12~14 h,迁徙速度日峰值在12:00—14:00,春季日迁徙时间比秋季长,各时间段迁徙速度整体比秋季慢;(3)白尾海雕度夏地95%MCP活动区面积为1 844.38 km2,主要利用栖息地类型为森林(71.78%)、水体(17.23%)和湿地(9.86%),对湿地和水体存在偏好利用,越冬地95%MCP活动区面积为410.68 km2,主要利用草地(81.59%)和裸地(18.09%)。本研究记录了白尾海雕完整年周期迁徙路线,揭示了其迁徙活动规律和栖息地利用状况,为白尾海雕种群和栖息地保护提供了重要基础资料。
Modelling the impact of toxic and disturbance stress on white-tailed eagle (Haliaeetus albicilla) populations
Several studies have related breeding success and survival of sea eagles to toxic or non-toxic stress separately. In the present investigation, we analysed single and combined impacts of both toxic and disturbance stress on populations of white-tailed eagle ( Haliaeetus albicilla ), using an analytical single-species model. Chemical and eco(toxico)logical data reported from laboratory and field studies were used to parameterise and validate the model. The model was applied to assess the impact of ∑PCB, DDE and disturbance stress on the white-tailed eagle population in The Netherlands. Disturbance stress was incorporated through a 1.6% reduction in survival and a 10–50% reduction in reproduction. ∑PCB contamination from 1950 up to 1987 was found to be too high to allow the return of white-tailed eagle as a breeding species in that period. ∑PCB and population trends simulated for 2006–2050 suggest that future population growth is still reduced. Disturbance stress resulted in a reduced population development. The combination of both toxic and disturbance stress varied from a slower population development to a catastrophical reduction in population size, where the main cause was attributed to the reduction in reproduction of 50%. Application of the model was restricted by the current lack of quantitative dose–response relationships between non-toxic stress and survival and reproduction. Nevertheless, the model provides a first step towards integrating and quantifying the impacts of multiple stressors on white-tailed eagle populations.
The Distribution of Nesting White-bellied Sea-eagle (Haliaeetus leucogaster) in Penang National Park, Malaysia: Conservation and Management Issues
Taman Negara Pulau Pinang (Penang National Park) is the only site on Pulau Pinang that supports a large population of the White-bellied Sea-eagle (WBSE) Haliaeetus leucogaster; however, the nesting sites of WBSEs have not been widely studied. As information on the location of WBSE nesting sites is very important for conservation works by local authorities, the objective of this study was to determine the distribution of nesting WBSEs in the coastal dipterocarp forest of Penang National Park. Surveys were conducted from December 2007 to July 2008 and October 2008 to April 2009, covering the breeding season of the species (September-July). The nesting sites were observed by boat along the coastline of Penang National Park and by performing ground surveys along the seashore at accessible areas; the nest survey was conducted three days/month from 0900 to 1500. A total of 34 WBSE nesting sites was located. Most of the occupied nests (seven nests) were found at Muka Head and Pantai Kerachut areas, which exhibit the densest concentration of occupied WBSE habitat in Penang National Park. WBSEs preferred to build their nests around Muka Head, which could be due to the frequent occurrence of whirlpools in the water body around that area. Aquatic animals, such as sea snakes and fish, stunned by the whirlpools would emerge to the sea surface, facilitating the foraging and feeding of WBSEs. Our results indicate that it is important to maintain and improve areas of suitable nesting habitat for WBSEs. Management actions should include (1) the yearly monitoring of known breeding sites throughout Penang National Park during the breeding season to determine breeding success over time, (2) recognising the critical habitat or nest-site selection of WBSEs, (3) establishment of a buffer zone surrounding nesting sites and potential habitat from human disturbance, and (4) encouraging on-going research to further understand this species.