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86-579: The gray fox ( Urocyon cinereoargenteus ), or grey fox , is an omnivorous mammal of the family Canidae , widespread throughout North America and Central America . This species and its only congener , the diminutive island fox ( Urocyon littoralis ) of the California Channel Islands , are the only living members of the genus Urocyon , which is considered to be genetically sister to all other living canids. Its species name cinereoargenteus means " ashen silver". It
172-412: A domestic cat . The gray fox is primarily nocturnal or crepuscular and makes its den in hollow trees, stumps or appropriated burrows during the day. Such gray fox tree dens may be located 30 ft (9 m) above the ground. For the most part, they rest on the ground rather than higher up in trees. Prior to European colonization of North America, the red fox was found primarily in boreal forest and
258-661: A type section , Global Boundary Stratotype Section and Point (GSSP), for the upper Pleistocene/Holocene boundary ( i.e. the upper boundary). The proposed section is the North Greenland Ice Core Project ice core 75° 06' N 42° 18' W. The lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama (C2r) chronozone , isotopic stage 103. Above this point there are notable extinctions of
344-497: A behavioral aspect, this would make them omnivores, but from the physiological standpoint, this may be due to zoopharmacognosy . Physiologically, animals must be able to obtain both energy and nutrients from plant and animal materials to be considered omnivorous. Thus, such animals are still able to be classified as carnivores and herbivores when they are just obtaining nutrients from materials originating from sources that do not seemingly complement their classification. For instance, it
430-752: A black-tipped tail, while the skull can be easily distinguished from all other North American canids by its widely separated temporal ridges that form a 'U'-shape. Like other canids, the fox's ears and muzzle are angular and pointed. Its claws tend to be lengthier and curved. There is little sexual dimorphism , save for the females being slightly smaller than males. The gray fox ranges from 76 to 112.5 cm (29.9 to 44.3 in) in total length. The tail measures 27.5 to 44.3 cm (10.8 to 17.4 in) of that length and its hind feet measure 100 to 150 mm (3.9 to 5.9 in). The gray fox typically weighs 3.6 to 7 kg (7.9 to 15.4 lb), though exceptionally can weigh as much as 9 kg (20 lb). The gray fox
516-611: A change from low-amplitude glacial cycles with a dominant periodicity of 41,000 years to asymmetric high-amplitude cycles dominated by a periodicity of 100,000 years. However, a 2020 study concluded that ice age terminations might have been influenced by obliquity since the Mid-Pleistocene Transition, which caused stronger summers in the Northern Hemisphere . Glaciation in the Pleistocene
602-469: A change was finally confirmed in 2009 by the International Union of Geological Sciences , the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of
688-574: A deviation from today's annual mean temperature, taken as zero. This sort of graph is based on another isotope ratio versus time. Ratios are converted to a percentage difference from the ratio found in standard mean ocean water (SMOW). The graph in either form appears as a waveform with overtones . One half of a period is a Marine isotopic stage (MIS). It indicates a glacial (below zero) or an interglacial (above zero). Overtones are stadials or interstadials. According to this evidence, Earth experienced 102 MIS stages beginning at about 2.588 Ma BP in
774-421: A few regions had been studied and the names were relatively few. Today the geologists of different nations are taking more of an interest in Pleistocene glaciology. As a consequence, the number of names is expanding rapidly and will continue to expand. Many of the advances and stadials remain unnamed. Also, the terrestrial evidence for some of them has been erased or obscured by larger ones, but evidence remains from
860-466: A habitat that will allow them to escape the coyote threat as much as possible, hence the choice of habitat nearer to areas where humans are active. The larger predators of the gray fox, like coyotes and bobcats, tend to avoid human-use areas and paved roads, making this habitat useful for the gray fox. They heavily utilize the edges of forests as a travel corridor, which is used for primary movement from place to place. Their choices do not change based on sex,
946-423: A mean of 3.8 young per female. The sexual maturity of females is around 10 months of age. Kits begin to hunt with their parents at the age of 3 months. By the time that they are 4 months old, the kits will have developed their permanent dentition and can now easily forage on their own. The family group remains together until the autumn, when the young males reach sexual maturity, then they disperse. In
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#17328010563911032-483: A mix of wooded and agricultural land in the Midwest, juniper forests as well as ponderosa pine in the west, and deciduous forests in the east. It is the only canid whose natural range spans both North and South America. In some areas, high population densities exist near brush-covered bluffs. The species prefers a mix of forest and agricultural land towards the southern part of their range (Belize ). In southeastern Mexico,
1118-491: A study of 9 juvenile gray foxes, only the males dispersed up to 84 km (52 mi). The juvenile females stayed within proximity of the den within 3 km (1.9 mi) and always returned. On the other hand, adult gray foxes showed no signs of dispersion for either gender. The gray fox will typically live between six and ten years. The annual reproductive cycle of males has been described through epididymal smears and become fertile earlier and remain fertile longer than
1204-578: A team of Russian scientists in collaboration with Princeton University announced that they had brought two female nematodes frozen in permafrost , from around 42,000 years ago, back to life. The two nematodes, at the time, were the oldest confirmed living animals on the planet. The evolution of anatomically modern humans took place during the Pleistocene. At the beginning of the Pleistocene Paranthropus species were still present, as well as early human ancestors, but during
1290-450: A variety of tapeworms ( Mesocestoides litteratus , Taenia pisiformis , Taenia serialis ) and roundworms ( Ancylostoma caninum , Ancylostoma braziliense , Haemonchus similis , Spirocerca lupi , Physaloptera rara , Eucoleus aerophilus ). T. pisiformis was the most common parasite species and was associated with frequent impacts on health. Omnivorous An omnivore ( / ˈ ɒ m n ɪ v ɔːr / )
1376-530: Is 66 (diploid) with a fundamental number of 70. The autosomes include 31 pairs of sub-graded subacrocentrics, but one only pair of metacentrics. Recent mitochondrial genetic studies suggests divergence of North American eastern and western gray foxes in the Irvingtonian mid-Pleistocene into separate sister taxa. The gray fox's dwarf relative, the island fox , is likely descended from mainland gray foxes. These foxes apparently were transported by humans to
1462-595: Is a taxon for species classification, no such equivalent exists for omnivores, as omnivores are widespread across multiple taxonomic clades . The Carnivora order does not include all carnivorous species, and not all species within the Carnivora taxon are carnivorous . (The members of Carnivora are formally referred to as carnivorans.) It is common to find physiological carnivores consuming materials from plants or physiological herbivores consuming material from animals, e.g. felines eating grass and deer eating birds. From
1548-486: Is a canid whose diet is naturally 50% plant matter. Like most arboreal species, squirrels are primarily granivores, subsisting on nuts and seeds. However, like virtually all mammals , squirrels avidly consume some animal food when it becomes available. For example, the American eastern gray squirrel has been introduced to parts of Britain, continental Europe and South Africa. Its effect on populations of nesting birds
1634-528: Is a question of context and emphasis, rather than of definition. Pleistocene The Pleistocene ( / ˈ p l aɪ s t ə ˌ s iː n , - s t oʊ -/ PLY -stə-seen, -stoh- ; referred to colloquially as the Ice Age ) is the geological epoch that lasted from c. 2.58 million to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations . Before
1720-1587: Is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates , protein , fat , and fiber , and metabolize the nutrients and energy of the sources absorbed. Often, they have the ability to incorporate food sources such as algae , fungi , and bacteria into their diet. Omnivores come from diverse backgrounds that often independently evolved sophisticated consumption capabilities. For instance, dogs evolved from primarily carnivorous organisms ( Carnivora ) while pigs evolved from primarily herbivorous organisms ( Artiodactyla ). Despite this, physical characteristics such as tooth morphology may be reliable indicators of diet in mammals, with such morphological adaptation having been observed in bears. The variety of different animals that are classified as omnivores can be placed into further sub-categories depending on their feeding behaviors . Frugivores include cassowaries , orangutans and grey parrots ; insectivores include swallows and pink fairy armadillos ; granivores include large ground finches and mice . All of these animals are omnivores, yet still fall into special niches in terms of feeding behavior and preferred foods. Being omnivores gives these animals more food security in stressful times or makes possible living in less consistent environments. The word omnivore derives from Latin omnis 'all' and vora , from vorare 'to eat or devour', having been coined by
1806-729: Is estimated that, at maximum glacial extent, 30% of the Earth's surface was covered by ice. In addition, a zone of permafrost stretched southward from the edge of the glacial sheet, a few hundred kilometres in North America , and several hundred in Eurasia . The mean annual temperature at the edge of the ice was −6 °C (21 °F); at the edge of the permafrost, 0 °C (32 °F). Each glacial advance tied up huge volumes of water in continental ice sheets 1,500 to 3,000 metres (4,900–9,800 ft) thick, resulting in temporary sea-level drops of 100 metres (300 ft) or more over
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#17328010563911892-602: Is limited, since the diet, behavior, and phylogeny of one omnivorous species may be very different from that of another: for instance, an omnivorous pig digging for roots and scavenging for fruit and carrion is taxonomically and ecologically quite distinct from an omnivorous chameleon that eats leaves and insects. The term "omnivory" is also not always comprehensive because it does not deal with mineral foods such as salt licks or with non-omnivores that self-medicate by consuming either plant or animal material which they otherwise would not (i.e. zoopharmacognosy ). Though Carnivora
1978-459: Is no systematic correspondence between pluvials to glacials, however. Moreover, regional pluvials do not correspond to each other globally. For example, some have used the term "Riss pluvial" in Egyptian contexts. Any coincidence is an accident of regional factors. Only a few of the names for pluvials in restricted regions have been stratigraphically defined. The sum of transient factors acting at
2064-600: Is often serious because of consumption of eggs and nestlings. Various birds are omnivorous, with diets varying from berries and nectar to insects , worms , fish , and small rodents . Examples include cranes , cassowaries , chickens , crows and related corvids , kea , rallidae , and rheas . In addition, some lizards (such as Galapagos Lava Lizard ), turtles , fish (such as piranhas and catfish ), and invertebrates are omnivorous. Quite often, mainly herbivorous creatures will eagerly eat small quantities of animal food when it becomes available. Although this
2150-543: Is primarily insectivorous and herbivorous. Fruit is an important component of the diet of the gray fox and they seek whatever fruits are readily available, generally eating more vegetable matter than does the red fox ( Vulpes vulpes ). Generally, there is an increase in fruits and invertebrates (such as grasshoppers , beetles , butterflies , and moths ) within the gray fox's diet in the transition from winter to spring. As nuts, grains, and fruits become more numerous, they are cached by foxes. Typically, they attempt to cover
2236-400: Is readily distinguished from the red fox by its obvious lack of the "black stockings" that stand out on the red fox. The grey fox has a stripe of black hair that runs along the middle of its tail, and individual guard hairs that are banded with white, gray, and black. The gray fox displays white on the ears, throat, chest, belly, and hind legs. Gray foxes also have black around their eyes, on
2322-577: Is trivial most of the time, omnivorous or herbivorous birds, such as sparrows, often will feed their chicks insects while food is most needed for growth. On close inspection it appears that nectar-feeding birds such as sunbirds rely on the ants and other insects that they find in flowers, not for a richer supply of protein, but for essential nutrients such as cobalt / vitamin b12 that are absent from nectar. Similarly, monkeys of many species eat maggoty fruit, sometimes in clear preference to sound fruit. When to refer to such animals as omnivorous, or otherwise,
2408-528: Is true for many insects, such as beetles in the family Meloidae, which begin by eating animal tissue as larvae , but change to eating plant matter after they mature. Likewise, many mosquito species in early life eat plants or assorted detritus, but as they mature, males continue to eat plant matter and nectar whereas the females (such as those of Anopheles , Aedes and Culex ) also eat blood to reproduce effectively. Although cases exist of herbivores eating meat and carnivores eating plant matter,
2494-480: Is well documented that animals such as giraffes, camels, and cattle will gnaw on bones, preferably dry bones, for particular minerals and nutrients. Felines , which are usually regarded as obligate carnivores, occasionally eat grass to regurgitate indigestibles (e.g. hair, bones), aid with hemoglobin production, and as a laxative. Occasionally, it is found that animals historically classified as carnivorous may deliberately eat plant material. For example, in 2013, it
2580-659: The Alpine ice sheet on the Alps . Scattered domes stretched across Siberia and the Arctic shelf. The northern seas were ice-covered. South of the ice sheets large lakes accumulated because outlets were blocked and the cooler air slowed evaporation. When the Laurentide Ice Sheet retreated, north-central North America was completely covered by Lake Agassiz . Over a hundred basins, now dry or nearly so, were overflowing in
2666-542: The Paleolithic age used in archaeology . The name is a combination of Ancient Greek πλεῖστος ( pleîstos ) 'most' and καινός ( kainós ; Latinized as cænus ) 'new'. At the end of the preceding Pliocene, the previously isolated North and South American continents were joined by the Isthmus of Panama , causing a faunal interchange between the two regions and changing ocean circulation patterns, with
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2752-662: The Ruwenzori Range in east and central Africa were larger. Glaciers existed in the mountains of Ethiopia and to the west in the Atlas Mountains . In the northern hemisphere, many glaciers fused into one. The Cordilleran Ice Sheet covered the North American northwest; the east was covered by the Laurentide . The Fenno-Scandian ice sheet rested on northern Europe , including much of Great Britain;
2838-437: The calcareous nannofossils : Discoaster pentaradiatus and Discoaster surculus . The Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. Formerly, the boundary between the two epochs was drawn at the time when the foraminiferal species Hyalinea baltica first appeared in the marine section at La Castella, Calabria, Italy. However,
2924-456: The fox-like canids confirmed that the gray fox is a distinct genus from the red foxes ( Vulpes spp.). The genus Urocyon is considered to be sister to the other living canid taxa. Genetically, the gray fox often clusters with two other ancient lineages: The east Asian raccoon dog ( Nyctereutes procyonoides ) and the African bat-eared fox ( Otocyon megalotis ). The chromosome number
3010-530: The giant sloth , the elephant-like Cuvieronius , the large-headed llama , and the early small horses of Nannippus and Equus . Faunal remains at two northern California cave sites confirm the presence of the gray fox during the late Pleistocene . Genetic analysis has shown that the gray fox migrated into the northeastern United States post-Pleistocene in association with the Medieval Climate Anomaly warming trend. Genetic analyses of
3096-477: The last glacial period ended about 10,000 years ago. Over 11 major glacial events have been identified, as well as many minor glacial events. A major glacial event is a general glacial excursion, termed a "glacial." Glacials are separated by "interglacials". During a glacial, the glacier experiences minor advances and retreats. The minor excursion is a "stadial"; times between stadials are "interstadials". These events are defined differently in different regions of
3182-412: The order Carnivora), and behaviorally (they subsist on a largely carnivorous diet). Depending on the species of bear, there is generally a preference for one class of food, as plants and animals are digested differently. Canines including wolves , dogs , dingoes , and coyotes eat some plant matter, but they have a general preference and are evolutionarily geared towards meat. However, the maned wolf
3268-599: The woolly rhinoceros , various giraffids , such as the Sivatherium ; ground sloths , Irish elk , cave lions , cave bears , Gomphotheres , American lions , dire wolves , and short-faced bears , began late in the Pleistocene and continued into the Holocene. Neanderthals also became extinct during this period. At the end of the last ice age, cold-blooded animals, smaller mammals like wood mice , migratory birds, and swifter animals like whitetail deer had replaced
3354-654: The "Tarantian"). In addition to these international subdivisions, various regional subdivisions are often used. In 2009 the International Union of Geological Sciences (IUGS) confirmed a change in time period for the Pleistocene, changing the start date from 1.806 to 2.588 million years BP, and accepted the base of the Gelasian as the base of the Pleistocene, namely the base of the Monte San Nicola GSSP . The start date has now been rounded down to 2.580 million years BP. The IUGS has yet to approve
3440-569: The Early Pleistocene Gelasian . Early Pleistocene stages were shallow and frequent. The latest were the most intense and most widely spaced. By convention, stages are numbered from the Holocene, which is MIS1. Glacials receive an even number and interglacials receive an odd number. The first major glacial was MIS2-4 at about 85–11 ka BP. The largest glacials were 2, 6, 12, and 16. The warmest interglacials were 1, 5, 9 and 11. For matching of MIS numbers to named stages, see under
3526-409: The Earth's surface is cyclical: climate, ocean currents and other movements, wind currents, temperature, etc. The waveform response comes from the underlying cyclical motions of the planet, which eventually drag all the transients into harmony with them. The repeated glaciations of the Pleistocene were caused by the same factors. The Mid-Pleistocene Transition , approximately one million years ago, saw
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3612-726: The French and later adopted by the English in the 1800s. Traditionally the definition for omnivory was entirely behavioral by means of simply "including both animal and vegetable tissue in the diet. " In more recent times, with the advent of advanced technological capabilities in fields like gastroenterology , biologists have formulated a standardized variation of omnivore used for labeling a species' actual ability to obtain energy and nutrients from materials. This has subsequently conditioned two context-specific definitions. The taxonomic utility of omnivore's traditional and behavioral definition
3698-479: The North American west. Lake Bonneville , for example, stood where Great Salt Lake now does. In Eurasia, large lakes developed as a result of the runoff from the glaciers. Rivers were larger, had a more copious flow, and were braided . African lakes were fuller, apparently from decreased evaporation. Deserts, on the other hand, were drier and more extensive. Rainfall was lower because of the decreases in oceanic and other evaporation. It has been estimated that during
3784-496: The Pleistocene's overall climate could be characterised as a continuous El Niño with trade winds in the south Pacific weakening or heading east, warm air rising near Peru , warm water spreading from the west Pacific and the Indian Ocean to the east Pacific, and other El Niño markers. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places. It
3870-805: The Pleistocene, the East Antarctic Ice Sheet thinned by at least 500 meters, and that thinning since the Last Glacial Maximum is less than 50 meters and probably started after ca 14 ka. During the 2.5 million years of the Pleistocene, numerous cold phases called glacials ( Quaternary ice age ), or significant advances of continental ice sheets, in Europe and North America, occurred at intervals of approximately 40,000 to 100,000 years. The long glacial periods were separated by more temperate and shorter interglacials which lasted about 10,000–15,000 years. The last cold episode of
3956-411: The Pleistocene, the plates upon which they sit probably having moved no more than 100 km (62 mi) relative to each other since the beginning of the period. In glacial periods, the sea level would drop by up to 120 m (390 ft) lower than today during peak glaciation, exposing large areas of the present continental shelf as dry land. According to Mark Lynas (through collected data),
4042-633: The Pleistocene. The climate was strongly variable depending on the glacial cycle, with the sea levels being up to 120 metres (390 ft) lower than present at peak glaciation, allowing the connection of Asia and North America via Beringia and the covering of most of northern North America by the Laurentide Ice Sheet . Charles Lyell introduced the term "Pleistocene" in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today. This distinguished it from
4128-468: The United States, the most common parasite of the gray fox is a flea ( Pulex simulans ); however, several new parasitic arthropods were found in populations in central Mexico, and a warming climate may encourage them to migrate north. Gray foxes are hunted in the U.S. The intensity of the hunting has correlated with the value of their pelts . Between the 1970–1971 and 1975–1976 hunting seasons,
4214-535: The Younger Dryas is the official start of the current Holocene Epoch . Although it is considered an epoch, the Holocene is not significantly different from previous interglacial intervals within the Pleistocene. In the ICS timescale, the Pleistocene is divided into four stages or ages , the Gelasian , Calabrian , Chibanian (previously the unofficial "Middle Pleistocene"), and Upper Pleistocene (unofficially
4300-706: The appearance of Homo sapiens about 300,000 years ago. Artifacts associated with modern human behavior are unambiguously attested starting 40,000–50,000 years ago. According to mitochondrial timing techniques, modern humans migrated from Africa after the Riss glaciation in the Middle Palaeolithic during the Eemian Stage , spreading all over the ice-free world during the late Pleistocene. A 2005 study posits that humans in this migration interbred with archaic human forms already outside of Africa by
4386-538: The area with their scent either through their scent glands or urine. This marking serves the dual purpose of allowing them to find the food again later and preventing other animals from taking it. Since woodrats, cotton rats, and mice make up a large part of the gray fox's diet, they serve as important regulators of small rodent populations. In addition to their beneficial predation on rodents, gray foxes are also less welcome hosts to some external and internal parasites, which include fleas, lice, nematodes, and tapeworms. In
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#17328010563914472-527: The articles for those names. Both marine and continental faunas were essentially modern but with many more large land mammals such as Mammoths , Mastodons , Diprotodons , Smilodons , tigers , lions , Aurochs , short-faced bears , giant sloths , species within Gigantopithecus and others. Isolated landmasses such as Australia , Madagascar , New Zealand and islands in the Pacific saw
4558-671: The classification "omnivore" refers to the adaptation and main food source of the species in general, so these exceptions do not make either individual animals or the species as a whole omnivorous. For the concept of "omnivore" to be regarded as a scientific classification , some clear set of measurable and relevant criteria would need to be considered to differentiate between an "omnivore" and other categories, e.g. faunivore , folivore , and scavenger . Some researchers argue that evolution of any species from herbivory to carnivory or carnivory to herbivory would be rare except via an intermediate stage of omnivory. Various mammals are omnivorous in
4644-538: The climate variation more extreme. The Late Pleistocene witnessed the spread of modern humans outside of Africa as well as the extinction of all other human species. Humans also spread to the Australian continent and the Americas for the first time, co-incident with the extinction of most large-bodied animals in these regions. The aridification and cooling trends of the preceding Neogene were continued in
4730-550: The day to avoid their larger, diurnal competitors. Still, gray foxes frequently fall victim to bobcats and coyotes. When killed, the carcasses are often unconsumed, suggesting they are victims of intraguild predation . These gray foxes are often killed on or near the boundary of their established range, when they begin to interfere with their competitors. Gray foxes are known as mesopredators because they are mid-tier predators and their prey consists mostly of smaller mammals, while coyotes are known as de facto apex predators due to
4816-598: The eastern U.S., though it will readily catch voles , shrews , and birds . In California, the gray fox primarily eats rodents (such as deer mice , woodrats , and cotton rats ), followed by lagomorphs , e.g. jackrabbit , brush rabbit , etc. When available, gray foxes may also feed on carrion . In some parts of the Western United States (such as in the Zion National Park in Utah), the gray fox
4902-618: The entire surface of the Earth. During interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global. Antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap. There were glaciers in New Zealand and Tasmania . The current decaying glaciers of Mount Kenya , Mount Kilimanjaro , and
4988-782: The evolution of large birds and even reptiles such as the Elephant bird , moa , Haast's eagle , Quinkana , Megalania and Meiolania . The severe climatic changes during the Ice Age had major impacts on the fauna and flora. With each advance of the ice, large areas of the continents became depopulated, and plants and animals retreating southwards in front of the advancing glacier faced tremendous stress. The most severe stress resulted from drastic climatic changes, reduced living space, and curtailed food supply. A major extinction event of large mammals ( megafauna ), which included mammoths , mastodons , saber-toothed cats , glyptodons ,
5074-414: The fertility of females. Logs, trees, rocks, burrows, or abandoned dwellings serve as suitable den sites. Dens are used at any time during the year but mostly during whelping season. Dens are built in brushy or wooded regions and are better concealed than the dens of the red fox . The gray fox is an omnivorous , solitary hunter. It frequently preys on the eastern cottontail ( Sylvilagus floridanus ) in
5160-414: The glacial range, which have their own glacial history depending on latitude, terrain and climate. There is a general correspondence between glacials in different regions. Investigators often interchange the names if the glacial geology of a region is in the process of being defined. However, it is generally incorrect to apply the name of a glacial in one region to another. For most of the 20th century, only
5246-485: The gray fox appears smaller because its fur is not as long and it has shorter limbs. The dental formula of U. cinereoargenteus is 3.1.4.2 3.1.4.3 = 42. The gray fox appeared in North America during the mid- Pliocene (Hemphillian land animal age) epoch 3.6 million years ago ( AEO ) with the first fossil evidence found at the lower 111 Ranch site, Graham County, Arizona with contemporary mammals like
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#17328010563915332-466: The gray fox as their prevalent fox . The genus Urocyon comes from Ancient Greek οὐρά (ourá, “tail”) + κύων (kúōn, “dog”). The species epithet cinereoargenteus is a combination of 'cinereo' (from 'cinereus') meaning ashen, and 'argenteus' (from argentum ), meaning 'silver', referencing the color of the tail. The gray fox is mainly distinguished from most other canids by its grizzled upper parts, black stripe down its tail and strong neck, ending in
5418-411: The gray fox in deciduous forest. With the increase in human populations in North America, their habitat selection has adapted: Gray foxes that live near human populations tend to choose areas near hardwood trees, locations used primarily by humans, or roads to utilize as their habitat. The increase of coyote populations around North America has reduced certain fox populations, so gray foxes have to choose
5504-450: The historical terminology was established. Corresponding to the terms glacial and interglacial, the terms pluvial and interpluvial are in use (Latin: pluvia , rain). A pluvial is a warmer period of increased rainfall; an interpluvial is of decreased rainfall. Formerly a pluvial was thought to correspond to a glacial in regions not iced, and in some cases it does. Rainfall is cyclical also. Pluvials and interpluvials are widespread. There
5590-420: The islands and from island to island, and are descended from a minimum of 3–4 matrilineal founders. The species occurs throughout most rocky, wooded, brushy regions of the southern half of North America from southern Canada ( Manitoba through southeastern Quebec ) to the northern part of South America ( Venezuela and Colombia ), excluding the mountains of northwestern United States. The species prefers
5676-622: The large amounts of material moved about by glaciers. Less common are cave deposits, travertines and volcanic deposits (lavas, ashes). Pleistocene marine deposits are found primarily in shallow marine basins mostly (but with important exceptions) in areas within a few tens of kilometres of the modern shoreline. In a few geologically active areas such as the Southern California coast, Pleistocene marine deposits may be found at elevations of several hundred metres. The modern continents were essentially at their present positions during
5762-409: The lips, and on their noses. In contrast to the species in genus Vulpes , such as the red fox , the gray fox has oval (instead of slit-like) pupils. The gray fox also has reddish coloration on parts of its body, including the legs, sides, feet, chest, and back and sides of the head and neck. The stripe on the fox's tail ends in a black tip as well. Its weight can be similar to that of a red fox, but
5848-470: The lower Palaeolithic they disappeared, and the only hominin species found in fossilic records is Homo erectus for much of the Pleistocene. Acheulean lithics appear along with Homo erectus , some 1.8 million years ago, replacing the more primitive Oldowan industry used by A. garhi and by the earliest species of Homo . The Middle Paleolithic saw more varied speciation within Homo , including
5934-478: The megafauna and migrated north. Late Pleistocene bighorn sheep were more slender and had longer legs than their descendants today. Scientists believe that the change in predator fauna after the late Pleistocene extinctions resulted in a change of body shape as the species adapted for increased power rather than speed. The extinctions hardly affected Africa but were especially severe in North America where native horses and camels were wiped out. In July 2018,
6020-581: The older Pliocene Epoch , which Lyell had originally thought to be the youngest fossil rock layer. He constructed the name "Pleistocene" ('most new' or 'newest') from the Greek πλεῖστος ( pleīstos ) 'most' and καινός ( kainós ( Latinized as cænus ) 'new'). This contrasts with the immediately preceding Pliocene ("newer", from πλείων ( pleíōn , "more") and kainós ) and the immediately subsequent Holocene ("wholly new" or "entirely new", from ὅλος ( hólos , "whole") and kainós ) epoch , which extends to
6106-700: The onset of glaciation in the Northern Hemisphere occurring around 2.7 million years ago. During the Early Pleistocene (2.58–0.8 Ma), archaic humans of the genus Homo originated in Africa and spread throughout Afro-Eurasia . The end of the Early Pleistocene is marked by the Mid-Pleistocene Transition , with the cyclicity of glacial cycles changing from 41,000-year cycles to asymmetric 100,000-year cycles, making
6192-465: The present time. The Pleistocene has been dated from 2.580 million (±0.005) to 11,700 years BP with the end date expressed in radiocarbon years as 10,000 carbon-14 years BP. It covers most of the latest period of repeated glaciation , up to and including the Younger Dryas cold spell. The end of the Younger Dryas has been dated to about 9700 BCE (11,700 calendar years BP). The end of
6278-469: The price of gray fox pelts greatly increased and the number of individuals hunted jumped over six-fold from 26,109 to 163,458. It has been recently reported that over 500,000 gray foxes are killed every year for their fur. There are 16 subspecies recognized for the gray fox. Parasites of gray fox include trematode Metorchis conjunctus . Other common parasites that were collected on gray foxes in Texas were
6364-417: The ratio of O to O (two isotopes of oxygen ) by mass (measured by a mass spectrometer ) present in the calcite of oceanic core samples is used as a diagnostic of ancient ocean temperature change and therefore of climate change. Cold oceans are richer in O , which is included in the tests of the microorganisms ( foraminifera ) contributing the calcite. A more recent version of
6450-682: The removal of other apex predators, like wolves, in North America. This explains the gray fox's tendency to change behavior in response to the coyote threat, as they are essentially lower on the food chain. The gray fox is assumed to be monogamous , like other foxes. The breeding season of the gray fox varies geographically; in Michigan , the gray fox mates in early March, in Alabama , breeding peaks occur in February. The gestation period lasts approximately 53 days. Litter size ranges from 1–7, with
6536-570: The revised definition of the Quaternary , by pushing back the start date of the Pleistocene to 2.58 Ma, results in the inclusion of all the recent repeated glaciations within the Pleistocene. Radiocarbon dating is considered to be inaccurate beyond around 50,000 years ago. Marine isotope stages (MIS) derived from Oxygen isotopes are often used for giving approximate dates. Pleistocene non-marine sediments are found primarily in fluvial deposits , lakebeds, slope and loess deposits as well as in
6622-488: The same food, the gray fox has been observed to give space to the coyote, staying within its own established range for hunting. Gray foxes might also avoid their competitors by occupying different habitats from them. In California, gray foxes do this by living in chaparral where their competitors are fewer and the low shrubbery provides them a greater chance to escape from a dangerous encounter. It also has been suggested that gray foxes could be more active at night than during
6708-407: The sampling process makes use of modern glacial ice cores. Although less rich in O than seawater, the snow that fell on the glacier year by year nevertheless contained O and O in a ratio that depended on the mean annual temperature. Temperature and climate change are cyclical when plotted on a graph of temperature versus time. Temperature coordinates are given in the form of
6794-451: The season, or the time of day. They also do the majority of their hunting in edges, and use them to escape from predators as well. Gray foxes are thus known as an "edge species". Gray foxes often hunt for the same prey as bobcats and coyotes who occupy the same region. To avoid interspecific competition , the gray fox has developed certain behaviors and habits to increase their survival chances. In regions where gray foxes and coyotes hunt for
6880-649: The sole factor responsible for the variations in climate since they explain neither the long-term cooling trend over the Plio-Pleistocene nor the millennial variations in the Greenland Ice Cores known as Dansgaard-Oeschger events and Heinrich events. Milankovitch pacing seems to best explain glaciation events with periodicity of 100,000, 40,000, and 20,000 years. Such a pattern seems to fit the information on climate change found in oxygen isotope cores. In oxygen isotope ratio analysis, variations in
6966-501: The species prefers areas with a human presence such as near roads. The gray fox is specifically adapted to climb trees. Its strong, hooked claws allow it to scramble up trees to escape many predators, such as the domestic dog or the coyote , or to reach tree-bound or arboreal food sources. It can climb branchless, vertical trunks to heights of 18 metres (59 ft) and jump from branch to branch. It descends primarily by jumping from branch to branch, or by descending slowly backwards like
7052-421: The study of cyclical climate changes. The glacials in the following tables show historical usages, are a simplification of a much more complex cycle of variation in climate and terrain, and are generally no longer used. These names have been abandoned in favour of numeric data because many of the correlations were found to be either inexact or incorrect and more than four major glacials have been recognised since
7138-539: The wild, such as species of hominids , pigs , badgers , bears , foxes , coatis , civets , hedgehogs , opossums , skunks , sloths , squirrels , raccoons , chipmunks , mice , hamsters and rats . Most bear species are omnivores, but individual diets can range from almost exclusively herbivorous ( hypocarnivore ) to almost exclusively carnivorous ( hypercarnivore ), depending on what food sources are available locally and seasonally. Polar bears are classified as carnivores, both taxonomically (they are in
7224-543: Was a series of glacials and interglacials, stadials and interstadials, mirroring periodic climate changes. The main factor at work in climate cycling is now believed to be Milankovitch cycles . These are periodic variations in regional and planetary solar radiation reaching the Earth caused by several repeating changes in the Earth's motion. The effects of Milankovitch cycles were enhanced by various positive feedbacks related to increases in atmospheric carbon dioxide concentrations and Earth's albedo. Milankovitch cycles cannot be
7310-568: Was considered that American alligators ( Alligator mississippiensis ) may be physiologically omnivorous once investigations had been conducted on why they occasionally eat fruits. It was suggested that alligators probably ate fruits both accidentally and deliberately. "Life-history omnivores" is a specialized classification given to organisms that change their eating habits during their life cycle. Some species, such as grazing waterfowl like geese, are known to eat mainly animal tissue at one stage of their lives, but plant matter at another. The same
7396-417: Was once the most common fox in the eastern United States , and though still found there, human advancement and deforestation allowed the red fox to become the predominant fox-like canid . Despite this post-colonial competition, the gray fox has been able to thrive in urban and suburban environments, one of the best examples being southern Florida . The Pacific States and Great Lakes region still have
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