نتایج جستجو برای: every year a large number of migratory wintering water birds
تعداد نتایج: 23379012 فیلتر نتایج به سال:
power transformers are important equipments in power systems. thus there is a large number of researches devoted of power transformers. however, there is still a demand for future investigations, especially in the field of diagnosis of transformer failures. in order to fulfill the demand, the first part reports a study case in which four main types of failures on the active part are investigate...
BACKGROUND For most Afro-Palearctic migrants, particularly small songbirds, spatiotemporal migration schedules and migratory connectivity remain poorly understood. We mapped migration from breeding through winter of one of the smallest Afro-Palearctic migrants, the willow warbler Phylloscopus trochilus, using geolocators (n = 15). RESULTS Birds migrated from North European breeding grounds to...
there are two major theories of measurement in psychometrics: classical test theory (ctt) and item-response theory (irt). despite its widespread and long use, ctt has a number of shortcomings, which make it problematic to be used for practical and theoretical purposes. irt tries to solve these shortcomings, and provide better and more dependable answers. one of the applications of irt is the as...
Populations of most North American aerial insectivores have undergone steep population declines over the past 40 years but the relative importance of factors operating on breeding, wintering, or stopover sites remains unknown. We used archival light-level geolocators to track the phenology, movements and winter locations of barn swallows (Hirdundo rustica; n = 27) from populations across North ...
The Great Salt Lake ecosystem is widely recognized to be unique and to have very high environmental and commercial value. Great Salt Lake is recognized regionally, nationally, and hemispherically for its extensive wetlands, and its tremendous and often unparalleled values to migratory birds. These values are derived from the lake’s unique physical features, including its immense size, dynamic w...
The migratory biology and connectivity of passerines remains poorly known, even for those that move primarily within the temperate zone. We used light-level geolocators to describe the migratory geography of a North American temperate migrant passerine. From February to March of 2010, we attached geolocator tags to 33 Golden-crowned Sparrows (Zonotrichia atricapilla) wintering on the central co...
At present, about 160,000 and 100,000 cranes are migrating on the West-European and on the Baltic-Hungarian routes, respectively, from the northern, middle, and northeastern parts of Europe. On both routes, the resting maxima, simultaneously determined since the 1980’s, has increased three-fold. This increase in migratory cranes is the result of shorter migration routes with higher return rates...
BACKGROUND The ability to connect breeding, stopover and wintering locations of populations of migratory birds greatly enhances our understanding of the phenomenon of migration and improves our chances of effectively conserving these species. Among Palearctic-Afrotropical migratory species, aerial insectivores like the house martin (Delichon urbicum) are sensitive to factors influencing the ava...
Many migratory bird species show high levels of site fidelity to their wintering sites, which confers advantages due to prior knowledge, but may also limit the ability of the individual to move away from degrading sites or to detect alternative foraging opportunities. Winter site fidelity often varies among age groups, but sexual differences have seldom been recorded in birds. We studied a popu...
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