نتایج جستجو برای: feathers
تعداد نتایج: 2568 فیلتر نتایج به سال:
Feathers have been widely used to assess mercury contamination in birds as they reflect metal concentrations accumulated between successive moult periods: they are also easy to sample and have minimum impact on the study birds. Moult is considered the major pathway for mercury excretion in seabirds. Penguins are widely believed to undergo a complete, annual moult during which they do not feed. ...
Honest advertisement models posit that sexually selected traits are costly to produce, maintain or otherwise bear. Brightly coloured feathers are thought to be classic examples of these models, but evidence for a cost in feathers not coloured by carotenoid pigments is scarce. Unlike pigment-based colours, iridescent feather colours are produced by light scattering in modified feather barbules t...
Birds-of-paradise are nature's prime examples of the evolution of color by sexual selection. Their brilliant, structurally colored feathers play a principal role in mating displays. The structural coloration of both the occipital and breast feathers of the bird-of-paradise Lawes' parotia is produced by melanin rodlets arranged in layers, together acting as interference reflectors. Light reflect...
Ectodermal appendages such as feathers, hair, mammary glands, salivary glands, and sweat glands form branches, allowing much-increased surface for functional differentiation and secretion. Here, the principles of branching morphogenesis are exemplified by the mammary gland and feathers.
Suzanne: Indeed, there are other species of birds related to peacocks that use feather vibrations in a very similar way during mating displays, including the Great Argus and a variety of Peacock Pheasants. Some birds species have feathers that make sounds due to vibrations driven by the passage of air over the feathers during flight,while others drive the vibrations using specially adapted feat...
Mercury is a persistent, toxic heavy metal that can bioaccumulate in organisms, causing diseases and other health problems. Wilson’s snipe (Gallinago delicata) feed primarily on aquatic invertebrates, which makes them prone to mercury bioaccumulation. In this study, we measured total mercury in Wilson’s snipe. Total mercury was measured in the feathers and muscle tissue. Mean concentration (ppm...
Total mercury levels in different feather types (down, contour, tail and flight) in Great Cormorants (Phalacrocorax carbo L.) were determined using CV-AAS. Feathers from Great Cormorants inhabiting the Vistula Lagoon ecosystem have an average Hg level of 7.14 ± 3.99 (μg/g w.w.). Age-dependent concentrations of Hg were statistically significant (ANOVA Kruskal-Wallis, p < 0.0001). There were also...
The feathers of Amazon parrots are brightly coloured. They contain a unique class of pigments, the psittacofulvins, deposited in both barbs and barbules, causing yellow or red coloured feathers. In specific feather areas, spongy nanostructured barb cells exist, reflecting either in the blue or blue-green wavelength range. The blue-green spongy structures are partly enveloped by a blue-absorbing...
Monitoring of avian productivity and tail feathers
Dietary T-2 toxin (0, 1, 2, 4, 8, and 16 mug./g.) was fed to 4 groups of 10 chickens at each treatment level from hatching until 3 weeks of age. Growth inhibitory levels (4, 8, and 16 mug./g.) caused abnormal feathering which appeared dose related. The chickens were sparsely covered with short feathers protruding at odd angles in comparison to controls. There were few feathers on the base of th...
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