نتایج جستجو برای: every year a large number of migratory wintering water birds
تعداد نتایج: 23379012 فیلتر نتایج به سال:
Migratory connectivity by birds may mutually affect different ecosystems over large distances. Populations of geese overwintering in southern areas while breeding in high-latitude ecosystems have increased strongly over the past decades. The increase is likely due to positive feedbacks caused by climate change at both wintering, stopover sites and breeding grounds, land-use practices at the ove...
•Plasma lipid metabolites may be useful indicators of mass changes in migratory birds. To test utility of plasma metabolites in field studies, we examined effects of several extrinsic (bleed time, time of day, location) and intrinsic (body mass, sex, age, migratory state) factors on plasma concentrations of triglycérides (TRIG), glycerol (GLYC), and B-OHbutyrate (BUTY) in free-living Western Sa...
Abstract Seasonal migration is intrinsically connected to the balance of survival and reproduction, but whether migratory behavior influences species’ position on slow-fast continuum life history poorly understood. We found that boreal-breeding birds migrate long distances exhibit higher annual adult lower reproductive investment relative co-distributed boreal species shorter winter closer thei...
During migration, passerine birds typically complete a series of multi-hour flights, each followed by a period of stopover. During flight, rates of respiratory water loss are high, yet these birds show no signs of dehydration after flights. During stopover, birds become hyperphagic to replenish fat reserves, often consuming food with high water content, such as fruit. Thus migratory birds seem ...
Several species of diurnal birds are nocturnal migrants. The activation of nocturnal activity requires major physiological changes, which are essentially unknown. Previous work has shown that during migratory periods nocturnal migrants have reduced night-time levels of melatonin. Since this hormone is involved in the modulation of day-night rhythms, it is a good candidate regulator of nocturnal...
Background and Objectives: HPAI has economic and public health importance. Aquatic and shore migratory birds are the main reservoirs and the cause of the spread of viruses across countries. The aim of study was risk assessment of the spread of the avian influenza H5 viruses. Methods: In this qualitative study, structured interviews and focus group discussions were used to assess the risk of...
Reproductive allochrony presents a potential barrier to gene flow and is common in seasonally sympatric migratory and sedentary birds. Mechanisms mediating reproductive allochrony can influence population divergence and the capacity of populations to respond to environmental change. We asked whether reproductive allochrony in seasonally sympatric birds results from a difference in response to s...
—Molecular markers and stable isotopes have provided important insights into the migratory connectivity of small landbirds. Research integrating these two methods has primarily focused on linking breeding and wintering sites, rather than focusing on timing of migratory movement of different breeding populations. We used mitochondrial DNA and isotopic markers to infer the timing of various breed...
BACKGROUND Migratory animals comprise a significant portion of biodiversity worldwide with annual investment for their conservation exceeding several billion dollars. Designing effective conservation plans presents enormous challenges. Migratory species are influenced by multiple events across land and sea-regions that are often separated by thousands of kilometres and span international border...
migratory birds are most often responsible for the distribution of avian diseases in different areas and serve as hosts for most parasites, including ectoparasites. the aim of the present study was to record the distribution range of a mesostigmatic mite species, dermanyssus gallinae in barn swallow nests in urmia suburb, north west of iran. the samples were collected from 161 bird nests in 44 ...
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