Gray Wolf ... Though once abundant over much of Eurasia, North Africa and North America, the gray wolf inhabits a reduced portion of its former range due to widespread destruction of its territory, human encroachment, and the resulting human-wolf encounters that sparked broad extirpation. Today, wolves are protected in some areas, hunted for sport in others, or may be subject to population control or extermination as threats to livestock, people, and pets...
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...
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...
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...
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...
Fish (food) ... The modern English word for fish comes from the Old English fisc (plural: fiscas) which was pronounced as it is today. Health benefits See also: Health benefits of eating seafood Research over the past few decades has shown that the nutrients and minerals in fish, and particularly the omega 3 fatty acids found in pelagic fishes, are heart-friendly and can make improvements in brain development and reproduction...
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...
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...
Bird Anatomy ... These sacs do not play a direct role in gas exchange, but act like bellows to move air through the respiratory system, allowing the lungs to maintain a fixed volume with fresh air constantly flowing through them. Three distinct sets of organs perform respiration—the anterior air sacs (interclavicular, cervicals, and anterior thoracics), the lungs, and the posterior air sacs (posterior thoracics and abdominals)...
Bird Vision ... These give birds the ability to perceive not only the visible range but also the ultraviolet part of the spectrum, and other adaptations allow for the detection of polarised light or magnetic fields... Birds have proportionally more light receptors in the retina than mammals, and more nerve connections between the photoreceptors and the brain... Birds of prey have a very high density of receptors and other adaptations that maximise visual acuity...
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...
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...
Beak ... Etymology Although the word 'beak' was, in the past, generally restricted to the sharpened bills of birds of prey, in modern ornithology, the terms 'beak' and 'bill' are generally considered to be synonymous... All other extant birds have a narrow forked vomer that does not connect with other bones and is then termed as neognathous... The muscles that depress the lower mandible are usually weak except in a few birds such as the starlings and the extinct Huia which have well developed digastric muscles that aid in foraging by prying or gaping actions...
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...
Bird ... Modern birds are characterised by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton... All living species of birds have wings—the now extinct flightless moa of New Zealand were the only exception... Birds are social; they communicate using visual signals and through calls and songs, and participate in social behaviours, including cooperative breeding and hunting, flocking, and mobbing of predators...
Bird Migration ... Also, the longer days of the northern summer provide extended time for breeding birds to feed their young... This helps diurnal birds to produce larger clutches than related non-migratory species that remain in the tropics... As the days shorten in autumn, the birds return to warmer regions where the available food supply varies little with the season...
Vision In Fishes ... Lenses are normally spherical but can be slightly elliptical in some species. Compared to terrestrial vertebrates, fish lenses are generally more dense and spherical...
List Of Extinct Birds ... Currently there are approximately 10,000 species of birds, with an estimated 1,200 considered to be under threat of extinction. Island species in general, and flightless island species in particular are most at risk...
Bird Flight ... Gliding When gliding, both birds and gliders obtain both a vertical and a forward force from their wings...
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...
Origin Of Avian Flight ... We propose that birds evolved from predators that specialized in ambush from elevated sites, using their raptorial hindlimbs in a leaping attack...
Feathered Dinosaur ... In 1964, John Ostrom described Deinonychus antirrhopus, a theropod whose skeletal resemblance to birds seemed unmistakable...
Mercury In Fish ... This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone...
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...