Biomagnification ... Biological magnification often refers to the process whereby certain substances such as pesticides or heavy metals move up the food chain, work their way into rivers or lakes, and are eaten by aquatic organisms such as fish, which in turn are eaten by large birds, animals or humans. The substances become concentrated in tissues or internal organs as they move up the chain...
Bird Flight ... Gliding When gliding, both birds and gliders obtain both a vertical and a forward force from their wings...
Iron In Folklore ... Francis Grose's 1811 Dictionary of the Vulgar Tongue defines cold iron as "A sword, or any other weapon for cutting or stabbing." This usage often appears as "cold steel" in modern parlance. "Cold iron" is sometimes asserted to repel, contain, or harm ghosts, fairies, witches, and/or other malevolent supernatural creatures...
Egg Tooth ... Some lizards and snakes develop a true tooth that is shed after use; other reptiles and birds generally develop an analogous epidermal horn that is reabsorbed or falls off...
Veterinary Physician ... In many countries, the local nomenclature for a vet is a regulated and protected term, meaning that members of the public without the prerequisite qualifications and/or registration are not able to use the title. In many cases, the activities that may be undertaken by a veterinarian (such as animal treatment or surgery) are restricted only to those professionals who are registered as vet...
Cat ... Cats are similar in anatomy to the other felids, with strong, flexible bodies, quick reflexes, sharp retractable claws, and teeth adapted to killing small prey. As crepuscular predators, cats use their acute hearing and ability to see in near darkness to locate prey...
Fish ... Because the term "fish" is defined negatively, and excludes the tetrapods (i.e., the amphibians, reptiles, birds and mammals) which descend from within the same ancestry, it is paraphyletic, and is not considered a proper grouping in systematic biology...
Diversity Of Fish ... Unlike groupings such as birds or mammals, fish are not a single clade but a paraphyletic collection of taxa, including jawless, cartilaginous and skeletal types...
Origin Of Birds ... A close relationship between birds and dinosaurs was first proposed in the nineteenth century after the discovery of the primitive bird Archaeopteryx in Germany... Fossil evidence also demonstrates that birds and dinosaurs shared features such as hollow, pneumatized bones, gastroliths in the digestive system, nest-building and brooding behaviors... A second molecular study robustly supported the relationship of birds to dinosaurs, though it did not place birds within Theropoda, as expected...
Evolution Of Birds ... Origins Main article: Origin of birds See also: Avicephala There is significant evidence that birds emerged within theropod dinosaurs, specifically, that birds are members of Maniraptora, a group of theropods which includes dromaeosaurs and oviraptorids, among others... As more non-avian theropods that are closely related to birds are discovered, the formerly clear distinction between non-birds and birds becomes less so...
Feather ... Hatchling birds of some species have a special kind of natal down (neossoptiles) and these are pushed out when the normal feathers (teleoptiles) emerge... It is noted that the pattern of orientation of β-keratin fibers in the feathers of flying birds differs from that in flightless birds... Color patterns serve as camouflage against predators for birds in their habitats, and by predators looking for a meal...
Raptor Conservation ... Placement of poles in prime habitat or along migration routes has caused higher mortality, and rates increase late in the summer during fledging when young, inexperienced birds proliferate... Bathing behavior at times of rain or snow makes birds more conductive to electricity, and orientation of pole cross arms with regard to prevailing winds can increase risk of contact with electrical components depending on ease of take off and landing...
Bird Conservation ... See Late Quaternary prehistoric birds for birds which disappeared in prehistoric and early historic times, usually due to human activity (i.e., starting with the Upper Paleolithic Revolution)... Threats to birds Habitat loss The most critical threat facing threatened birds is the destruction and fragmentation of habitat...
Flight Feather ... Corresponding remiges on individual birds are symmetrical between the two wings, matching to a large extent in size and shape (except in the case of mutation or damage), though not necessarily in pattern... The flexibility of the remiges on the wingtips of large soaring birds also allows for the spreading of those feathers, which helps to reduce the creation of wingtip vortices, thereby reducing drag... The barbules on these feathers, friction barbules, are specialized with large lobular barbicels that help grip and prevent slippage of overlying feathers and are present in most of the flying birds...
Animal Navigation ... William Tinsley Keeton (1933-1980) studied homing pigeons, showing that they were able to navigate using the earth's magnetic field, the sun, as well as both olfactory and visual cues. Donald Griffin (1915-2003) studied echolocation in bats, demonstrating that it was possible and that bats used this mechanism to detect and track prey, and to "see" and thus navigate through the world around them...
Brood Parasite ... Interspecific brood-parasites include the Old World cuckoos in Eurasia and Australia, cowbirds and Black-headed Ducks in the Americas, and indigobirds, whydahs, and the honeyguides in Africa. Seven independent origins of obligate interspecific brood parasitism in birds have been proposed...