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...
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...
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...
Bird Flight ... Gliding When gliding, both birds and gliders obtain both a vertical and a forward force from their wings...
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...
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...
Feral Cat ... In many parts of the world, feral cats are descendants of domestic cats that were left behind by travelers. Because cats are not native to all parts of the world, feral cats can cause harm to local environments by preying on local species...
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...
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...
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...
Wolves In Ireland ... The Morrígan was said to take on the form of a red-furred wolf, particularly in her battle with the hero Cú Chulainn. Mac Cecht killed a wolf feeding on a still living woman on a battlefield...
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...
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)...
Feathered Dinosaur ... In 1964, John Ostrom described Deinonychus antirrhopus, a theropod whose skeletal resemblance to birds seemed unmistakable...
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...
The Origin Of Birds (book) ... Based essentially on a process of elimination, Heilmann arrives at the conclusion that birds must be descended from thecodonts, a group of archosaurs which lived during the Permian and Triassic periods... Although this conclusion was later shown to be inaccurate, The Origin of Birds was regarded as a masterful piece of scholarship at the time and set the international agenda for research in bird evolution for nearly half a century, and much of its research remains of interest... They had been discovered just a few decades after the discovery of the dinosaurs, and as some dinosaurs appeared somewhat birdlike, Archaeopteryx was regarded as a possible "missing link" between reptiles and birds by many paleontologists at the time...
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...
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...
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...
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 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...
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...
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...