question_text: what is considered the maximum length of an rg58 segment

root

text: RG-58/U is a type of coaxial cable often used for low-power signal and RF connections. The cable has a characteristic impedance of either 50 or 52 Ω. "RG" was originally a unit indicator for bulk RF cable in the U.S. military's Joint Electronics Type Designation System. There are several versions covering the differences in core material (solid or braided wire) and shield (70% to 95% coverage).

tag: p

text: The outside diameter of RG-58 is around 0.2 inches (5 mm). RG-58 weighs around 0.025 lb/ft (37 g/m), exhibits approximately 25 pF/ft (82 pF/m) capacitance and can tolerate a maximum of 300 V potential (1800 W).[1] Plain RG-58 cable has a solid center conductor. The RG-58A/U features a flexible 7- or 19-strand center conductor.

text: Most two-way radio communication systems, such as marine, CB radio, amateur, police, fire, WLAN antennas etc., are designed to work with a 50 Ω cable.

text: RG-58 cable is often used as a generic carrier of signals in laboratories, combined with BNC connectors that are common on test and measurement equipment such as oscilloscopes.

text: RG-58 in versions RG-58A/U or RG-58C/U was once widely used in "thin" Ethernet (10BASE2), for which it provides a maximum segment length of 185 meters. However, it has been almost completely replaced by twisted-pair cabling such as Cat 5, Cat 6, and similar cables in data networking applications.

text: RG-58 cable can be used for moderately high frequencies. Its signal attenuation depends on the frequency, e.g. from 10.8 dB per 100 m (3.3 dB per 100 feet) at 50 MHz to 70.5 dB per 100 m (21.5 dB per 100 feet) at 1 GHz.[2]


document_title: Grizzly bear

question_text: how many grizzly bears are there in montana

text: Grizzly bear

text: Classification

text: Meaning of "grizzly"

text: Meriwether Lewis and William Clark first described it as grisley, which could be interpreted as either "grizzly" (i.e., "grizzled"—that is, with golden and grey tips of the hair) or "grisly" ("fear-inspiring", now usually "gruesome").[6] The modern spelling supposes the former meaning; even so, naturalist George Ord formally classified it in 1815 as U. horribilis, not for its hair, but for its character.[7]

text: Evolution and genetics

text: Grizzly phylogenetics

text: Classification has been revised along genetic lines.[1] There are two morphological forms of Ursus arctos, the grizzly and the coastal brown bears, but these morphological forms do not have distinct mtDNA lineages.[8]

text: Ursus arctos - the brown bear

text:
Brown bears originated in Eurasia and traveled to North America approximately 50,000 years ago,[9][10] spreading into the contiguous United States about 13,000 years ago.[11]
In the 19th century, the grizzly was classified as 86 distinct species. However, by 1928 only seven grizzlies remained[2] and by 1953 only one species remained globally.[12] However, modern genetic testing reveals the grizzly to be a subspecies of the brown bear (Ursus arctos). Rausch found that North America has but one species of grizzly.[13] Therefore, everywhere it is the "brown bear"; in North America, it is the "grizzly", but these are all the same species, Ursus arctos.

text: Ursus arctos subspecies in North America

text: In 1963 Rausch reduced the number of North American subspecies to one, Ursus arctos middendorffi[14]

text: Further testing of Y-chromosomes is required to yield an accurate new taxonomy with different subspecies.[1]

text: Coastal grizzlies, often referred to by the popular but geographically redundant synonym of "brown bear" or "Alaskan brown bear" are larger and darker than inland grizzlies, which is why they, too, were considered a different species from grizzlies. Kodiak grizzly bears were also at one time considered distinct. Therefore, at one time there were five different "species" of brown bear, including three in North America.[15]

text: Appearance

text: Most adult female grizzlies weigh 130–180 kg (290–400 lb), while adult males weigh on average 180–360 kg (400–790 lb).  Average total length in this subspecies is 198 cm (6.50 ft), with an average shoulder height of 102 cm (3.35 ft) and hindfoot length of 28 cm (11 in).[16] Newborn bears may weigh less than 500 grams (1.1 lb). In the Yukon River area, mature female grizzlies can weigh as little as 100 kg (220 lb). One study found that the average weight for an inland male grizzly was around 272 kilograms (600 lb) and the average weight for a coastal male was around 408 kilograms (900 lb). For a female, these average weights would be 136 kilograms (300 lb) inland and 227 kilograms (500 lb) coastal, respectively.[17] On the other hand, an occasional huge male grizzly has been recorded which greatly exceeds ordinary size, with weights reported up to 680 kg (1,500 lb).[18] A large coastal male of this size may stand up to 3 metres (9.8 ft) tall on its hind legs and be up to 1.5 metres (4.9 ft) at the shoulder.[19]

text: Although variable in color from blond to nearly black, grizzly bear fur is typically brown with darker legs and commonly white or blond tipped fur on the flank and back.[20] A pronounced hump appears on their shoulders; the hump is a good way to distinguish a grizzly bear from a black bear, as black bears do not have this hump. Aside from the distinguishing hump a grizzly bear can be identified by a "dished in" profile of their face with short, rounded ears, whereas a black bear has a straight face profile and longer ears.[21] A grizzly bear can also be identified by its rump, which is lower than its shoulders, while a black bear's rump is higher.[21] A grizzly bear's front claws measure about 2–4 inches in length and a black bear's measure about 1–2 inches in length.[21]

text: Range and population

text: Brown bears are found in Asia, Europe, and North America, giving them the widest ranges of bear species.[2] They also inhabited North Africa and the Middle East.[22] In North America, grizzly bears previously ranged from Alaska down to Mexico and as far east as the western shores of Hudson Bay;[9] the species is now found in Alaska, south through much of western Canada, and into portions of the northwestern United States (including Idaho, Montana, Washington, and Wyoming), extending as far south as Yellowstone and Grand Teton National Parks. It is most commonly found in Canada. In Canada, there are approximately 25,000 grizzly bears occupying British Columbia, Alberta,  the Yukon, the Northwest Territories, Nunavut, and the northern part of Manitoba.[9] An article published in 1954 suggested they may be present in the tundra areas of the Ungava Peninsula and the northern tip of Labrador-Quebec.[23] In British Columbia, grizzly bears inhabit approximately 90% of their original territory. There were approximately 25,000 grizzly bears in British Columbia when the European settlers arrived.[9] However, population size has since significantly decreased due to hunting and habitat loss. In 2003, researchers from the University of Alberta spotted a grizzly on Melville Island in the high Arctic, which is the most northerly sighting ever documented.[24][25] In 2008, it was estimated there were 16,014 grizzly bears.  Population estimates for British Columbia are based on hair-snagging, DNA-based inventories, mark-and-recapture, and a refined multiple regression model.[26] A revised Grizzly bear count in 2012 for British Columbia was 15,075.[27]

text: The Alaskan population of 30,000 individuals is the highest population of any province/state in North America. Populations in Alaska are densest along the coast, where food supplies such as salmon are more abundant.[28] The Admiralty Island National Monument protects the densest population—1,600 bears on a 1,600-square mile island.[29]

text: North America

text: There are currently about 55,000 wild grizzly bears total located throughout North America, most of which reside in Alaska.[9] Only about 1,500 grizzlies are left in the lower 48 states of the US.[30] Of these, about 800 live in Montana.[31] About 600 more live in Wyoming, in the Yellowstone-Teton area.[32] There are an estimated 70–100 grizzly bears living in northern and eastern Idaho. Its original range included much of the Great Plains and the southwestern states, but it has been extirpated in most of those areas. Combining Canada and the United States, grizzly bears inhabit approximately half the area of their historical range.[9]

text: Although the once-abundant grizzly bear (see California grizzly bear) appears prominently on the state flag of California and was the symbol of the Bear Flag Republic before California's admission to the Union, they are no longer naturally present.  The last grizzly in all of California was killed in the Sierra foothills east of Fresno in August 1922.[33]

text: In September 2007, a hunter produced evidence of one bear in the Selway-Bitterroot Wilderness ecosystem, by killing a male grizzly bear there.[34] In the North Cascades ecosystem of northern Washington, grizzly bear populations are estimated to be fewer than 20 bears. One sighting of a grizzly bear in 2010 has been recorded.[35] There has been no confirmed sighting of a grizzly in Colorado since 1979.[36]

text: Other provinces and the United States may use a combination of methods for population estimates. Therefore, it is difficult to say precisely what methods were used to produce total population estimates for Canada and North America, as they were likely developed from a variety of studies. The grizzly bear currently has legal protection in Mexico, European countries, some areas of Canada and in the United States. However, it is expected that repopulating its former range will be a slow process, due to a variety of reasons including the bear's slow reproductive habits and the effects of reintroducing such a large animal to areas prized for agriculture and livestock. Competition with other predators and predation on cubs are other possible limiting factors for grizzly bear recovery, though grizzly bears also benefit from scavenged carcasses from predators as an easy food source when other food sources decline.

text: Biology

text: Hibernation

text: Grizzly bears hibernate for 5–7 months each year[37] except where the climate is warm, as the California grizzly did not hibernate.[2] During this time, female grizzly bears give birth to their offspring, who then consume milk from their mother and gain strength for the remainder of the hibernation period.[38] To prepare for hibernation, grizzlies must prepare a den, and consume an immense amount of food as they do not eat during hibernation. Grizzly bears do not defecate or urinate throughout the entire hibernation period. The male grizzly bear's hibernation ends in early to mid-March, while females emerge in April or early May.[39]

text: In preparation for winter, bears can gain approximately 180 kg (400 lb), during a period of hyperphagia, before going into hibernation.[40] The bear often waits for a substantial snowstorm before it enters its den: such behavior lessens the chances predators will find the den. The dens are typically at elevations above 1,800 m (5,900 ft) on north-facing slopes.[41] There is some debate amongst professionals as to whether grizzly bears technically hibernate: much of this debate revolves around body temperature and the ability of the bears to move around during hibernation on occasion. Grizzly bears can "partially" recycle their body wastes during this period.[42] Although inland or Rocky Mountain grizzlies spend nearly half of their life in dens, coastal grizzlies with better access to food sources spend less time in dens. In some areas where food is very plentiful year round, grizzly bears skip hibernation altogether.[43]

text: Reproduction

text: Except for females with cubs,[44] grizzlies are normally solitary, active animals, but in coastal areas, grizzlies gather around streams, lakes, rivers, and ponds during the salmon spawn. Every other year, females (sows) produce one to four young (usually two) that are small and weigh only about 450 grams (1 lb) at birth. A sow is protective of her offspring and will attack if she thinks she or her cubs are threatened.

text: Grizzly bears have one of the lowest reproductive rates of all terrestrial mammals in North America.[45] This is due to numerous ecological factors. Grizzly bears do not reach sexual maturity until they are at least five years old.[9][46] Once mated with a male in the summer, the female delays embryo implantation until hibernation, during which miscarriage can occur if the female does not receive the proper nutrients and caloric intake.[47] On average, females produce two cubs in a litter[46] and the mother cares for the cubs for up to two years, during which the mother will not mate.[9]

text: Once the young leave or are killed, females may not produce another litter for three or more years, depending on environmental conditions.[48] Male grizzly bears have large territories, up to 4,000 km2 (1,500 sq mi),[45] making finding a female scent difficult in such low population densities. Population fragmentation of grizzlies may destabilize the population from inbreeding depression. The gestation period for grizzly bears is approximately 180–250 days.

text: Litter size is between one and four cubs, averaging twins or triplets. Cubs are always born in the mother's winter den while she is in hibernation. Female grizzlies are fiercely protective of their cubs, being able to fend off predators as large as male bears bigger than they are in defense of the cubs.[49] Cubs feed entirely on their mother's milk until summer comes, after which they still drink milk but begin to eat solid foods. Cubs gain weight rapidly during their time with the mother—their weight will have ballooned from 4.5 to 45 kg (10 to 99 lb) in the two years spent with the mother. Mothers may see their cubs in later years but both avoid each other.[50]

text: Longevity

text: The grizzly bear is, by nature, a long-living animal. The average lifespan for a male is estimated at 22 years, with that of a female being slightly longer at 26.[51] Females live longer than males due to their less dangerous life; avoiding the seasonal breeding fights in which males engage. The oldest wild inland grizzly was 34 years old in Alaska; the oldest coastal bear was 39,[52] but most grizzlies die in their first few years of life from predation or hunting.[53] Captive grizzlies have lived as long as 44 years.[citation needed]

text: Ecology

text: Diet

text: Although grizzlies are of the order Carnivora and have the digestive system of carnivores, they are normally omnivores: their diets consist of both plants and animals. They have been known to prey on large mammals, when available, such as moose, elk, caribou, white-tailed deer, mule deer, bighorn sheep, bison, and even black bears; though they are more likely to take calves and injured individuals rather than healthy adults. Grizzly bears feed on fish such as salmon, trout, and bass, and those with access to a more protein-enriched diet in coastal areas potentially grow larger than inland individuals. Grizzly bears also readily scavenge food or carrion left behind by other animals.[54] Grizzly bears will also eat birds and their eggs, and gather in large numbers at fishing sites to feed on spawning salmon. They frequently prey on baby deer left in the grass, and occasionally they raid the nests of raptors such as bald eagles.[55]

text: Canadian or Alaskan grizzlies are larger than those that reside in the American Rocky Mountains. This is due, in part, to the richness of their diets. In Yellowstone National Park in the United States, the grizzly bear's diet consists mostly of whitebark pine nuts, tubers, grasses, various rodents, army cutworm moths, and scavenged carcasses.[56]  None of these, however, match the fat content of the salmon available in Alaska and British Columbia. With the high fat content of salmon, it is not uncommon to encounter grizzlies in Alaska weighing 540 kg (1,200 lb).[57] Grizzlies in Alaska supplement their diet of salmon and clams with sedge grass and berries. In areas where salmon are forced to leap waterfalls, grizzlies gather at the base of the falls to feed on and catch the fish. Salmon are at a disadvantage when they leap waterfalls because they cluster together at their bases and are therefore easier targets for the grizzlies.[58] Grizzly bears are well-documented catching leaping salmon in their mouths at Brooks Falls in Katmai National Park and Preserve in Alaska. They are also very experienced in chasing the fish around and pinning them with their claws.[59][60] At such sites such as Brooks Falls and McNeil Falls in Alaska, big male grizzlies fight regularly for the best fishing spots.[61] Grizzly bears along the coast also forage for razor clams, and frequently dig into the sand to seek them.[62] During the spring and fall, directly before and after the salmon runs, berries and grass make up the mainstay of the diets of coastal grizzlies.[63]

text: Inland grizzlies may eat fish too, most notably in Yellowstone grizzlies eating Yellowstone cutthroat trout.[64] The relationship with cutthroat trout and grizzlies is unique because it is the only example where Rocky Mountain grizzlies feed on spawning salmonid fish.[64] However, grizzly bears themselves and invasive lake trout threaten the survival of the trout population and there is a slight chance that the trout will be eliminated.[65]

text: Meat, as already described, is an important part of a grizzly's diet. Grizzly bears occasionally prey on small mammals, such as marmots, ground squirrels, lemmings, and voles.[66] The most famous example of such predation is in Denali National Park and Preserve, where grizzlies chase, pounce on, and dig up Arctic ground squirrels to eat.[67] In some areas, grizzly bears prey on hoary marmots, overturning rocks to reach them, and in some cases preying on them when they are in hibernation.[68] Larger prey includes bison and moose, which are sometimes taken by bears in Yellowstone National Park. Because bison and moose are dangerous prey, grizzlies usually use cover to stalk them and/or pick off weak individuals or calves.[69][70] Grizzlies in Alaska also regularly prey on moose calves, which in Denali National Park may be their main source of meat. In fact, grizzly bears are such important predators of moose and elk calves in Alaska and in Yellowstone, that they may kill as many as 51 percent of elk or moose calves born that year. Grizzly bears have also been blamed in the decline of elk in Yellowstone National Park when the actual predators were thought to be gray wolves.[71][72][73][74][75] In northern Alaska, grizzlies are a significant predator of caribou, mostly taking sick or old individuals or calves.[76] Several studies show that grizzly bears may follow the caribou herds year-round in order to maintain their food supply.[77][78] In northern Alaska, grizzly bears often encounter muskox. Despite the fact that muskox do not usually occur in grizzly habitat and that they are bigger and more powerful than caribou, predation on muskox by grizzlies has been recorded.[79]

text: Grizzly bears along the Alaskan coast also scavenge on dead or washed up whales.[80] Usually such incidents involve only one or two grizzlies at a carcass, but up to ten large males have been seen at a time eating a dead humpback whale. Dead seals and sea lions are also consumed.[citation needed]

text: Although the diets of grizzly bears vary extensively based on seasonal and regional changes, plants make up a large portion of them, with some estimates as high as 80–90%.[81] Various berries constitute an important food source when they are available. These can include blueberries, blackberries (Rubus fruticosus), salmon berries (Rubus spectabilis), cranberries (Vaccinium oxycoccos), buffalo berries (Shepherdia argentea), soapberries (Shepherdia canadensis), and huckleberries (Vaccinium parvifolium), depending on the environment. Insects such as ladybugs, ants, and bees are eaten if they are available in large quantities. In Yellowstone National Park, grizzly bears may obtain half of their yearly caloric needs by feeding on miller moths that congregate on mountain slopes.[82] When food is abundant, grizzly bears will feed in groups. For example, many grizzly bears will visit meadows right after an avalanche or glacier slide. This is due to an influx of legumes, such as Hedysarum, which the grizzlies consume in massive amounts.[83] When food sources become scarcer, however, they separate once again.

text: Interspecific competition

text: The removal of wolves and the grizzly bear in California may have greatly reduced the abundance of the endangered San Joaquin Kit Fox.[84] With the reintroduction of gray wolves to Yellowstone, many visitors have witnessed a once common struggle between a keystone species, the grizzly bear, and its historic rival, the gray wolf. The interactions of grizzly bears with the wolves of Yellowstone have been under considerable study. Typically, the conflict will be in the defense of young or over a carcass, which is commonly an elk killed by wolves.[85] The grizzly bear uses its keen sense of smell to locate the kill. As the wolves and grizzly compete for the kill, one wolf may try to distract the bear while the others feed. The bear then may retaliate by chasing the wolves. If the wolves become aggressive with the bear, it is normally in the form of quick nips at its hind legs. Thus, the bear will sit down and use its ability to protect itself in a full circle. Rarely do interactions such as these end in death or serious injury to either animal. One carcass simply is not usually worth the risk to the wolves (if the bear has the upper hand due to strength and size) or to the bear (if the wolves are too numerous or persistent).[86] While wolves usually dominate grizzly bears during interactions at wolf dens, both grizzly and black bears have been reported killing wolves and their cubs at wolf dens even when the latter was in defense mode.[87][88]

text: Black bears generally stay out of grizzly territory, but grizzlies may occasionally enter black bear terrain to obtain food sources both bears enjoy, such as pine nuts, acorns, mushrooms, and berries. When a black bear sees a grizzly coming, it either turns tail and runs or climbs a tree. Black bears are not strong competition for prey because they have a more herbivorous diet. Confrontations are rare because of the differences in size, habitats, and diets of the bear species. When this happens, it is usually with the grizzly being the aggressor. The black bear will only fight when it is a smaller grizzly such as a yearling or when the black bear has no other choice but to defend itself. There is at least one confirmed observation of a grizzly bear digging out, killing and eating a black bear when the latter was in hibernation.[89]

text: The segregation of black bear and grizzly bear populations is possibly due to competitive exclusion. In certain areas, grizzly bears outcompete black bears for the same resources.[90] For example, many Pacific coastal islands off British Columbia and Alaska support either the black bear or the grizzly, but rarely both.[91] In regions where both species coexist, they are divided by landscape gradients such as age of forest, elevation and openness of land. Grizzly bears tend to favor old forests with high productivity, higher elevations and more open habitats compared with black bears.[90]

text: The relationship between grizzly bears and other predators is mostly one-sided; grizzly bears will approach feeding predators to steal their kill. In general, the other species will leave the carcasses for the bear to avoid competition or predation. Any parts of the carcass left uneaten are scavenged by smaller animals.[92] Cougars generally give the bears a wide berth. Grizzlies have less competition with cougars than with other predators, such as coyotes, wolves, and other bears. When a grizzly descends on a cougar feeding on its kill, the cougar usually gives way to the bear. When a cougar does stand its ground, it will use its superior agility and its claws to harass the bear, yet stay out of its reach until one of them gives up. Grizzly bears occasionally kill cougars in disputes over kills.[93] There have been several accounts, primarily from the late 19th and early 20th centuries, of cougars and grizzly bears killing each other in fights to the death.[94] The other big cat that is present in the United States, which may pose as a threat to bears, is the jaguar.[95]

text: Coyotes, foxes, and wolverines are generally regarded as pests to the grizzlies rather than competition, though they may compete for smaller prey, such as ground squirrels and rabbits. All three will try to scavenge whatever they can from the bears. Wolverines are aggressive enough to occasionally persist until the bear finishes eating, leaving more scraps  than normal for the smaller animal.[92] Packs of coyotes have also displaced grizzly bears in disputes over kills.[96]

text: Ecological role

text: The grizzly bear has several relationships with its ecosystem. One such relationship is a mutualistic relationship with fleshy-fruit bearing plants. After the grizzly consumes the fruit, the seeds are excreted and thereby dispersed in a germinable condition. Some studies have shown germination success is indeed increased as a result of seeds being deposited along with nutrients in feces.[97] This makes grizzly bears important seed distributors in their habitats.[98]

text: While foraging for tree roots, plant bulbs, or ground squirrels, bears stir up the soil. This process not only helps grizzlies access their food, but also increases species richness in alpine ecosystems.[99] An area that contains both bear digs and undisturbed land has greater plant diversity than an area that contains just undisturbed land.[99] Along with increasing species richness, soil disturbance causes nitrogen to be dug up from lower soil layers, and makes nitrogen more readily available in the environment. An area that has been dug by the grizzly bear has significantly more nitrogen than an undisturbed area.[100]

text: Nitrogen cycling is not only facilitated by grizzlies digging for food, it is also accomplished via their habit of carrying salmon carcasses into surrounding forests.[101] It has been found that spruce tree (Picea glauca) foliage within 500 m (1,600 ft) of the stream where the salmon have been obtained contains nitrogen originating from salmon on which the bears preyed.[102] These nitrogen influxes to the forest are directly related to the presence of grizzly bears and salmon.[103]

text: Grizzlies directly regulate prey populations and also help prevent overgrazing in forests by controlling the populations of other species in the food chain.[104] An experiment in Grand Teton National Park in Wyoming in the United States showed removal of wolves and grizzly bears caused populations of their herbivorous prey to increase.[105] This, in turn, changed the structure and density of plants in the area, which decreased the population sizes of migratory birds.[105] This provides evidence grizzly bears represent a keystone predator, having a major influence on the entire ecosystem they inhabit.[104]

text: When grizzly bears fish for salmon along the coasts of Alaska and British Columbia, they often only eat the skin, brain and roe of the fish. In doing so, they provide a food source for gulls, ravens, and foxes, all of which eat salmon as well; this benefits both the bear and the smaller predators.[106]

text: Interaction with humans

text: Conflicts with humans

text: Grizzlies are considered more aggressive compared to black bears when defending themselves and their offspring.[107] Unlike the smaller black bears, adult grizzlies do not climb trees well and respond to danger by standing their ground and warding off their attackers.[108] Mothers defending cubs are the most prone to attacking, and are responsible for 70% of humans killed by grizzlies.[109]

text: Grizzly bears normally avoid contact with people. In spite of their obvious physical advantage they rarely actively hunt humans.[110] Most grizzly bear attacks result from a bear that has been surprised at very close range, especially if it has a supply of food to protect, or female grizzlies protecting their offspring.[111]  A bear killing a human in a national park may be killed to prevent its attacking again.[112]

text: Exacerbating this is the fact that intensive human use of grizzly habitat coincides with the seasonal movement of grizzly bears.[111]

text: Increased human–bear interaction has created "problem bears": bears adapted to human activities or habitat.[113] Aversive conditioning using rubber bullets, foul-tasting chemicals, or acoustic deterrent devices attempt to condition bears to associate humans with unpleasantness, but is ineffectual when bears have already learned to positively associate humans with food.[114] Such bears are translocated or killed because they pose a threat to humans. The B.C. government kills approximately 50 problem bears each year[114] and overall spends more than one million dollars annually to address bear complaints, relocate bears and kill them.[114]

text: Bear awareness programs have been developed by numerous towns in British Columbia, Canada, to help prevent conflicts with both black and grizzly bears. The main premise of these programs is to teach humans to manage foods that attract bears. Keeping garbage securely stored, harvesting fruit when ripe, securing livestock behind electric fences, and storing pet food indoors are all measures promoted by bear awareness programs.   The fact that grizzly bears are less numerous and even protected in some areas, means that preventing conflict with grizzlies is especially important.  Revelstoke, British Columbia is a community that demonstrates the success of this approach.  In the ten years preceding the development of a community education program in Revelstoke, 16 grizzlies were destroyed and a further 107 were relocated away from the town.  An education program run by Revelstoke Bear Aware was put in place in 1996. Since the program began just four grizzlies have been eliminated and five have been relocated.[115]

text: For back-country campers, hanging food between trees at a height unreachable to bears is a common procedure, although some grizzlies can climb and reach hanging food in other ways. An alternative to hanging food is to use a bear canister.[116]

text: Traveling in groups of six or more can significantly reduce the chance of bear-related injuries while hiking in bear country.[117]

text: Grizzly bears are especially dangerous because of the force of their bite, which has been measured at over 8 megapascals (1160 psi). It has been estimated that a bite from a grizzly could even crush a bowling ball.[118]

text: Protection

text: The grizzly bear is listed as threatened in the contiguous United States and endangered in parts of Canada. In May 2002, the Canadian Species at Risk Act listed the Prairie population (Alberta, Saskatchewan and Manitoba range) of grizzly bears as extirpated in Canada.[119] As of 2002, grizzly bears were listed as special concern under the COSEWIC registry[120] and considered threatened under the U.S. Fish and Wildlife Service.[121]

text: Within the United States, the U.S. Fish and Wildlife Service concentrates its effort to restore grizzly bears in six recovery areas. These are Northern Continental Divide (Montana), Yellowstone (Montana, Wyoming, and Idaho), Cabinet-Yaak (Montana and Idaho), Selway-Bitterroot (Montana and Idaho), Selkirk (Idaho and Washington), and North Cascades (Washington). The grizzly population in these areas is estimated at 750 in the Northern Continental Divide, 550 in Yellowstone, 40 in the Yaak portion of the Cabinet-Yaak, and 15 in the Cabinet portion (in northwestern Montana), 105 in Selkirk region of Idaho, 10–20 in the North Cascades, and none currently in Selway-Bitterroots, although there have been sightings.[122] These are estimates because bears move in and out of these areas, and it is therefore impossible to conduct a precise count. In the recovery areas that adjoin Canada, bears also move back and forth across the international boundary.

text: The U.S. Fish and Wildlife Service claims the Cabinet-Yaak and Selkirk areas are linked through British Columbia, a claim that is disputed.[123] U.S. and Canadian national parks, such as Banff National Park, Yellowstone and Grand Teton, and Theodore Roosevelt National Park are subject to laws and regulations designed to protect the bears.

text: On 9 January 2006, the US Fish and Wildlife Service proposed to remove Yellowstone grizzlies from the list of threatened and protected species.[124] In March 2007, the U.S. Fish and Wildlife Service "de-listed" the population,[125] effectively removing Endangered Species Act protections for grizzlies in the Yellowstone National Park area. Several environmental organizations, including the NRDC, brought a lawsuit against the federal government to relist the grizzly bear. On 22 September 2009, U.S. District Judge Donald W. Molloy reinstated protection due to the decline of whitebark pine tree, whose nuts are an important source of food for the bears.[126] In 1996 the International Union for Conservation of Nature moved the grizzly bear to the lower risk "Least Concern" status on the IUCN Red List.[127][128]

text: Farther north, in Alberta, Canada, intense DNA hair-snagging studies in 2000 showed the grizzly population to be increasing faster than what it was formerly believed to be, and Alberta Sustainable Resource Development calculated a population of 841 bears.[129] In 2002, the Endangered Species Conservation Committee recommended that the Alberta grizzly bear population be designated as threatened due to recent estimates of grizzly bear mortality rates that indicated the population was in decline. A recovery plan released by the provincial government in March 2008 indicated the grizzly population is lower than previously believed.[130] In 2010, the provincial government formally listed its population of about 700 grizzlies as "Threatened".[131]

text: Environment Canada consider the grizzly bear to a "special concern" species, as it is particularly sensitive to human activities and natural threats. In Alberta and British Columbia, the species is considered to be at risk.[132] In 2008, it was estimated there were 16,014 grizzly bears in the British Columbia population, which was lower than previously estimated due to refinements in the population model.[133]

text: The Mexican grizzly bear (Ursus arctos nelsoni) is extinct.[134][135]

text: Conservation efforts

text: Conservation efforts have become an increasingly vital investment over recent decades, as population numbers have dramatically declined. Establishment of parks and protected areas are one of the main focuses currently being tackled to help reestablish the low grizzly bear population in British Columbia. One example of these efforts is the Khutzeymateen Grizzly Bear Sanctuary located along the north coast of British Columbia; at 44,300 hectares (109,000 acres) in size, it is composed of key habitat for this threatened species. Regulations such as limited public access, as well as a strict no hunting policy, have enabled this location to be a safe haven for local grizzlies in the area.[136] When choosing the location of a park focused on grizzly bear conservation, factors such as habitat quality and connectivity to other habitat patches are considered.

text: The Refuge for Endangered Wildlife located on Grouse Mountain in Vancouver is an example of a different type of conservation effort for the diminishing grizzly bear population. The refuge is a five-acre terrain which has functioned as a home for two orphaned grizzly bears since 2001.[137] The purpose of this refuge is to provide awareness and education to the public about grizzly bears, as well as providing an area for research and observation of this secluded species.

text: Another factor currently being taken into consideration when designing conservation plans for future generations are anthropogenic barriers in the form of urban development and roads. These elements are acting as obstacles, causing fragmentation of the remaining grizzly bear population habitat and prevention of gene flow between subpopulations (for example, Banff National Park). This, in turn, is creating a decline in genetic diversity, and therefore the overall fitness of the general population is lowered.[138] In light of these issues, conservation plans often include migration corridors by way of long strips of "park forest" to connect less developed areas, or by way of tunnels and overpasses over busy roads.[139] Using GPS collar tracking, scientists can study whether or not these efforts are actually making a positive contribution towards resolving the problem.[140] To date, most corridors are found to be infrequently used, and thus genetic isolation is currently occurring, which can result in inbreeding and therefore an increased frequency of deleterious genes through genetic drift.[141] Current data suggest female grizzly bears are disproportionately less likely than males to use these corridors, which can prevent mate access and decrease the number of offspring.

text: In the United States, national efforts have been made since 1982 for the recovery plan of grizzly bears.[142] A lot of the efforts made have been through different organizations efforts to educate the public on grizzly bear safety, habits of grizzly bears and different ways to reduce human-bear conflict. The Interagency Grizzly Bear Recovery Committee is one of many organizations committed to the recovery of grizzly bears in the lower 48 states.[143] There are five recovery zones for grizzly bears in the lower 48 states including the North Cascades ecosystem in Washington state.[144] The National Park Service and U.S. Fish and Wildlife initiated the process of an environmental impact statement that started in the fall of 2014 to begin the recovery process of grizzly bears to the North Cascades region.[144] A final plan and environmental impact statement was released in the spring of 2017 with a record of decision to follow.[144][145]

text: In early March 2016, the U.S. Fish and Wildlife Service proposed to withdraw Endangered Species Act protections from grizzly bears in and around Yellowstone National Park. The population has risen from 136 bears in 1975 to an estimated 700 in 2017, and was "delisted" in June 2017.[144][146][145]

text: Bear-watching

text: In the past 20 years in Alaska, ecotourism has boomed. While many people come to Alaska to bear-hunt, the majority come to watch the bears and observe their habits. Some of the best bear viewing in the world occurs on coastal areas of the Alaska Peninsula, including in Lake Clark National Park and Preserve, Katmai National Park and Preserve, and the McNeil River State Game Sanctuary and Refuge. Here bears gather in large numbers to feast on concentrated food sources, including sedges in the salt marshes, clams in the nearby tidal flats, salmon in the estuary streams, and berries on the neighboring hillsides.

text: Katmai National Park and Preserve is one of the best spots to view brown bears. The bear population in Katmai is estimated at a healthy 2,100.[147] The park is located on the Alaskan Peninsula about 480 km (300 mi) southwest of the city of Anchorage. At Brooks Camp, a famous site exists where grizzlies can be seen catching salmon from atop a platform—you can even view this online from a cam.[148] In coastal areas of the park, such as  Hallo Bay, Geographic Harbor, Swikshak Lagoon, American Creek, Big River, Kamishak River, Savonoski River, Moraine Creek, Funnel Creek, Battle Creek, Nantuk Creek,[149] Kukak Bay, and Kaflia Bay you can often watch bears fishing alongside wolves, eagles, and river otters. Coastal areas host the highest population densities year round because there is a larger variety of food sources available, but Brooks Camp hosts the highest population (100 bears).[150]

text: The McNeil River State Game Sanctuary and Refuge, on the McNeil River, is home to the greatest concentration of brown bears in the world. An estimated 144 individual bears have been identified at the falls in a single summer with as many as 74 at one time;[151] 60 or more bears at the falls is a frequent sight, and it is not uncommon to see 100 bears at the falls throughout a single day.[152] The McNeil River State Game Refuge, containing Chenik Lake and a smaller number of grizzly bears, has been closed to grizzly hunting since 1995.[153] All of the Katmai-McNeil area is closed to hunting except for Katmai National Preserve, where regulated legal hunting takes place.[154] In all, the Katmai-McNeil area has an estimated 2,500 grizzly bears.[155]

text: Admiralty Island, in southeast Alaska, was known to early natives as Xootsnoowú, meaning "fortress of bears," and is home to the densest grizzly population in North America. An estimated 1600 grizzlies live on the island, which itself is only 140 km (90 mi) long.[156] One place to view grizzly bears in the island is probably Pack Creek, in the Stan Price State Wildlife Sanctuary. 20 to 30 grizzlies can be observed at the creek at one time and like Brooks Camp, visitors can watch bears from an above platform.[157] Kodiak Island, hence its name, is another place to view bears. An estimated 3,500 Kodiak grizzly bears inhabit the island, 2,300 of these in the Kodiak National Wildlife Refuge.[158][159] The O'Malley River is considered the best place on Kodiak Island to view grizzly bears.[160]


document_title: Comparison of American and Canadian football

question_text: how many players are on the field in the cfl

question_tokens: how many players are on the field in the cfl

text: Comparison of American and Canadian football

text: History[edit]

text: Rugby football was introduced to North America in Canada by the British Army garrison in Montreal, Quebec, which played a series of games with McGill University.[1]  In 1874, the U.S. Harvard University hosted Canada's McGill University to play the new game derived from rugby football in a home-and-home series. When the Canadians arrived several days early, to take advantage of the trip to see Boston and the surrounding areas, they held daily practices. During this time, the Americans were surprised to see the Canadians kick, chase, and then run with the ball. Picking up and running with the ball violated a basic rule of the American game of the day; when the U.S. captain (Henry Grant) pointed this out to the captain of the Canadian team (David Roger), the reply was simple: Running with the ball is a core part of the Canadian game. When the American asked which game the Canadians played, David replied "rugby". After some negotiation, it was decided to play a game with half and half Canadian/U.S. rules. Thus, many of the similarities and differences between the Canadian and American games indeed came out of this original series where each home team set the rules. For instance, Harvard, because of a lack of campus space, did not have a full-sized rugby pitch. Their pitch was only 100 yd (91 m) long by 50 yd (46 m) wide with undersized end zones (slightly less than the 53⅓-yard width of the current regulation-sized field for American football). Because of the reduced field, the Harvard team opted for 11 players per side, four fewer than the regulation 15 of Rugby Union. To generate more offense, Harvard also increased the number of downs from three, as set by McGill, to four. Furthermore, the Harvard players so enjoyed running with the ball, this rule was wholly adopted into all Harvard play following the two games with McGill. While the American team bested the Canadian (3-0 and a following tie game), both countries' flavours of football were forever changed and linked to one another. Both the Canadian and American games still have some things in common with the two varieties of rugby, especially rugby league, and because of the similarities, the National Football League (NFL) had a formal relationship with the Canadian Football League (CFL) between 1997 and 2008.[2]

text: Many, perhaps most, of the rules differences have arisen because of rules changes in American football in the early 20th century which have not been copied by Canadian football. The major Canadian codes never abolished the onside scrimmage kick (see Kicker advancing the ball below) or restricted backfield motion, while the American college football (from whose code all American codes derive) did. Canadian football was later in adopting the hand snap and the forward pass, although one would not suspect the latter from play today. Additionally, Canadian football was slower in removing restrictions on blocking, but caught up by the 1970s so that no significant differences remain today. Similarly, differences in scoring (the Canadian game valuing touchdowns less) opened up from the late 19th century, but were erased by the 1950s. An area in which American football has been more conservative is the retention of the fair catch (see below).

text: In some regions along the Canada-U.S. border, especially western areas, some high schools from opposite sides of the border regularly play games against one another (typically one or two per team per season). By agreement between the governing bodies involved, the field of the home team is considered a legal field, although it is a different size from one school's normal field. In all but a few cases, the rules of the home team are followed throughout the game.

text: Many CFL players are Americans who grew up playing American football and cannot find a place in the NFL, or who prefer to play in the CFL; strict import quotas restrict the number of non-Canadian players. Furthermore, the classifications of import (non-Canadian) and non-import (Canadian) were highly restrictive and required a player to have been in Canada since childhood to qualify as a non-import (i.e. a player cannot simply become a Canadian citizen and become a non-import, nor can he arrive in Canada during high school or college; both scenarios would still have the player in question classified as an import and counted against the team's maximum); these restrictions were loosened beginning in 2014 so that anyone who had become a Canadian citizen at any time before signing with the league for the first time could qualify as a non-import player. For individuals who played both American and Canadian football professionally, their career statistic totals are considered to be their combined totals from their careers in both the CFL and NFL. Warren Moon, for example, was the all-time professional football leader in passing yards after an illustrious career in both leagues. He was surpassed in 2006 by Damon Allen, who in turn was surpassed by Anthony Calvillo in 2011, both of whose careers were exclusively in the CFL.

text: Differences[edit]

text: There are several important specific differences between the Canadian and American versions of the game of football:

text: Playing area[edit]

text: The official playing field in Canadian football is larger than the American, and similar to American fields prior to 1912. The Canadian field of play is 110 by 65 yards (101 by 59.4 m), rather than 100 by 53 1⁄3 yards (91.4 by 48.8 m) as in American football. The end zones in Canadian football are 10 yards deeper than American football end zones as the CFL uses 20-yard (18.3 m) end zones. Prior to 1986, however, the end zones were 25 yards, with Vancouver's BC Place the first to use the 20 yard-long end zone in 1983. However, beginning in 2016, the new home of the CFL's Toronto Argonauts, BMO Field, utilizes an 18-yard-long end zone.[3] Including the end zones, the Canadian field is almost 34% larger than the American field (87,750 square feet (8,152 m2) for the Canadian field vs 57,600 square feet (5,350 m2) for the American field). Occasionally, however, the Canadian field will have its end zone truncated at the corners so that the field fits in the infield of a running track. The only example in the CFL is the Percival Molson Memorial Stadium, home of the Montreal Alouettes. The goalposts for kicking are placed at the goal line in Canadian football and the end line in the American game. In Canadian rules, the distance between the sideline and hash marks is 24 yards (21.9 m); in American amateur rules, at the high school level, the distance is 17 yards 2 feet 4 inches (16.3 m), virtually sectioning the field into three equal columns. The hash marks are closer together at the American college level, where they are 20 yards (18.3 m) from the sideline, and in the NFL, where they are 23 yd 1 ft 9 in (21.6 m) from the sideline and the distance between them is the same as that between the goalposts.[4]

text: Because of the larger field, many American football venues are generally unfit for the Canadian game. While there are several American stadia which could accommodate the extra 17 1⁄2 feet (nearly 6 yards (5.5 m) per side in width (multi-purpose stadiums, baseball parks converted for football, and some soccer-specific stadiums are particularly good fits), most American stadia would lose between fifteen and eighteen rows of seating in each end zone because the field is 15 yards (13.7 m) longer on each end. In many smaller venues, this would be the entire end zone section, losing seating for at least 3,000 spectators. During the CFL's failed expansion to U.S. cities, Canadian football was either played on fields designed to accommodate both American football and baseball (such as the Baltimore Stallions playing at Memorial Stadium), or in some cases, on a field designed for American football (for instance, the Memphis Mad Dogs and the Birmingham Barracudas of the CFL, playing in the Liberty Bowl and at Legion Field, respectively, played the Canadian game on modified American-sized fields because of the inability of the stadia to adapt to the larger field). The Alamodome, originally built as a multi-purpose dome, proved to best accommodate both Canadian football (the CFL's San Antonio Texans) and American football (Alamo Bowl, Dallas Cowboys training camp, the New Orleans Saints after Hurricane Katrina, the NFLPA Game, the U.S. Army All-American Bowl and the UTSA Roadrunners), although Canadian football is no longer played there. Similarly, Hornet Stadium fairly easily adapted to both the Canadian and American game, as it was built with a running track in which the Canadian field fits with only some cuts to the corners. Hornet Stadium hosts California State University, Sacramento (more often known as Sacramento State), hosted the Sacramento Surge and Sacramento Mountain Lions in American football and hosted the Sacramento Gold Miners in Canadian football.[citation needed]

text: Team size[edit]

text: American teams use eleven players, while Canadian teams have twelve players on the field per side. Both games have the same number of offensive players required at the line of scrimmage, so the twelfth player in the Canadian game plays a backfield position on offence, whereas this is usually a defensive back on defence.[5]

text: Because of this, position designations of the various offensive and defensive lines vary. For example, there is no tight end in most formations in Canadian football (this position was phased out in 1980 in the Canadian game).[6] The typical offensive arrangement in Canadian football is for there to be two slotbacks instead of the American tight end, while on the defensive end of the ball, two defensive halfbacks are used instead of one strong safety in the American game.[citation needed]

text: The ball[edit]

text: The sizes of individual American and Canadian footballs can vary within specified size limitations. Because the ball size specifications for the CFL and NFL are nearly identical, the same ball can fall within the requirements of both.[citation needed]

text: Historically the CFL ball was slightly larger, both because of slightly bigger specifications, but also because CFL manufacturers tended to make balls at the larger end of the allowed tolerances as opposed to NFL manufacturers who built balls to the smaller end. However, the CFL updated its specifications in 1985.[7]

text: According to the current standards the regulation size for a Canadian Football League football is specified as: short circumference from 20 7⁄8 to 21 1⁄8 inches (530 to 537 mm); long circumference from 27 3⁄4 to 28 1⁄4 inches (705 to 718 mm).[8]

text: The regulation size for a National Football League football is specified as: short circumference from 21 to 21 1⁄4 inches (533 to 540 mm); long circumference from 28 to 28 1⁄2 inches (711 to 724 mm).[9]

text: Despite the fact that the CFL rules allow for a smaller legal ball and the NFL rules allow for a larger legal ball, there is a common misconception among media, fans, and even players that the current CFL ball is bigger. Some professional quarterbacks have stated that they notice a difference in size.[10]

text: Another difference between NFL and CFL balls is that Canadian balls have two 1 inch (25 mm) complete white stripes around the football 3 inches (76 mm) from the largest diameter of the ball and NFL balls have no stripes at all. College football and high school football both specify the use of stripes, but only on two of the football's four panels (the ones adjacent to the laces).[citation needed]

text: Number of downs[edit]

text: In American football, a team has four downs to advance the ball ten yards, while in Canadian football the limit is three downs.[11][12]

text: Scrimmage[edit]

text: In both games, the ball is placed at a line of scrimmage, in which a player known as the centre/center performs a snap to start a football play. In Canadian football, the snap is required to go between the centre's legs; there is no such requirement in American football, but it is invariably done this way anyway, so the center is in position to block following the snap. The defensive team must stay a set distance away from the line of scrimmage on their side of the line.[citation needed]

text: In Canadian football, the distance between the line of scrimmage and the defensive team is a full yard. Because of this one-yard distance, teams will tend to gamble on third and one or third and inches. If a team has possession within one yard of either goal line, the line of scrimmage is moved to the one-yard line.[13]

text: In American football, the set distance between the offensive and defensive teams is eleven inches – the length of the ball, creating the illusion of the teams being "nose-to-nose" against each other.[citation needed]

text: While large, relatively immobile offensive line players used to form a line that cannot be easily penetrated by the defense are valued in American football, the extra distance from the defensive team means Canadian football finds value in more nimble athletes.[14]

text: Fair catches and punt returns[edit]

text: In American football, if a punt returner sees that, in his judgment, he will be unable to advance the ball after catching it, he may signal for a fair catch by waving his hand in the air, and forgo the attempt to advance. If he makes this signal, the opposing team must allow him to attempt to catch the ball cleanly; if he is interfered with, the team covering the kick will be penalized fifteen yards. In contrast, there is no fair catch rule in Canadian football: instead no player from the kicking team, except the kicker or any player who was behind him when he kicked the ball, may approach within five yards of the ball until it has been touched by an opponent. If they do, a "no yards" penalty is called against the kicking team. Penalties for "no yards" calls vary on whether the ball made contact with the ground or not. The penalty is 5 yards if the ball has bounced and 15 if the ball is caught in the air.[15]

text: Furthermore, in American football the receiving team may elect not to play the ball if the prospects for a return are not good and the returner is not certain he can successfully catch the ball on the fly; American players are generally taught not to attempt to touch a bouncing football. If any member of the kicking team touches the ball after the kick is made, without an intervening touch by the member of the receiving team, the receiving team may elect to scrimmage the ball from that spot of first touching, regardless of anything else (other than a penalty) that happens during the rest of the play. If the kicking team gains possession of the ball during the kick before it is touched by the receiving team, the ball is then dead. Often, the ball hits the ground and is surrounded by players from the kicking team, who allow it to roll as far as possible downfield  – without going into the end zone  – before grasping or holding the ball against the ground. (If a punt bounces into the receiving team's end zone, it is dead, and a touchback is awarded.) On the other hand, if the ball touches a member of the receiving team without his gaining possession (a "muff"), then the ball can be recovered by either team (but cannot be advanced by the kicking team). If the kicking team recovers the ball, they regain possession and are awarded a first down at the spot of the recovery.[citation needed]

text: Following a fair catch in American football, the receiving team can elect a free kick (called a fair catch kick) from the spot the ball is received – and if the kick goes through the opposite goal posts a field goal is scored. Fair catch kicks are rarely attempted in the NFL and are usually unsuccessful (The last successful fair catch kick was in 1976). The fair catch kick is not allowed in college football.[citation needed]

text: In Canadian football, if the receiving team does not play the ball, the kicker, and any teammates behind the kicker at the time of the kick, can attempt to retrieve and advance the ball. This is further explained in the kicker advancing the ball section.[citation needed]

text: Motion at the snap[edit]

text: In American football, after all players are set, only one offensive player is allowed to be in motion, and he cannot be moving toward the line of scrimmage while the ball is snapped. The motion player must also be behind the line of scrimmage; players on the line cannot be in motion.[16]

text: In Canadian football, all offensive backfield players, except the quarterback, may be in motion at the snap  – players in motion may move in any direction as long as they are behind the line of scrimmage at the snap. In addition, the two players on the ends of the line of scrimmage (generally wide receivers) may also be in motion along the line.[13] Many teams encourage this unlimited motion, as it can confuse the defence. It also provides receivers the advantage of a running start, as they can time their runs so that they cross the line of scrimmage at speed when the ball is snapped, allowing them to get downfield faster than receivers in American football, allowing for comparatively longer throws in the same amount of time after the snap or quicker throws for a given distance.[citation needed]

text: Time rules[edit]

text: In American football, the offensive team must run a play within 25 seconds of the referee whistling the play in – except in the NCAA (college) and the NFL where teams have 40 seconds from the end of the previous play, or 25 seconds following a penalty or timeout. In Canadian football, teams have 20 seconds regardless of the preceding situation.[17]

text: American football rules allow each team to have three timeouts in each half, and the NFL stops play for a two-minute warning. However, NCAA football has no two-minute warning, but the clock stops on a first down until the ball is ready for play if the play ended in the field of play. In the CFL, each team has two time-outs a game but cannot use both in the last three minutes of the game, while at lower levels of Canadian football each team has two. In Canadian football there is a three-minute rather than a two-minute warning. Also, at all levels of Canadian football, the clock is stopped after every play during the last three minutes of each half. Once the referee has set the ball the clock will restart if the last play ended with a runner tackled in the field of play.[citation needed]

text: Timing rules change drastically after the N-minute warning in both leagues:

text:
In American football, the clock continues to run after any tackle in bounds, but stops after an incomplete pass, or a tackle out of bounds. If the clock stops, it is restarted at the snap of the ball or when the ball is ready to be played. In Canadian football, the clock stops after every play, but the starting time differs depending on the result of the previous play: After a tackle in bounds, the clock restarts when the referee whistles the ball in; after an incomplete pass or a tackle out of bounds, the clock restarts when the ball is snapped. In the NCAA the clock stops after every first down to move and set the down markers, after which the clock restarts.
The penalty for allowing the play clock to run out, which is 5 yards with no loss of down before the N-minute warning in both codes, dramatically diverges after that point. In American football, the penalty for "delay of game" remains 5 yards with the down repeated. In Canadian football, the penalty for a "time count" violation ("delay of game" is a different violation in Canada) is loss of down on first or second down, and 10 yards with the down repeated on third down. Also, if the referee deems a time count violation on third down after the three-minute warning to be deliberate, he has the right to require the offensive team to legally put the ball into play within the 20-second count, with a violation resulting in loss of possession. (Note that the enforcement of time count during convert attempts does not change at the warning; it is 5 yards with the down repeated throughout the game.)[18]
In American football, a period generally ends when time expires (though any play which is in progress when the clock reaches 0:00 is allowed to finish); in Canadian football, the period must end with a final play. Consequently, a play is often started in Canadian football with no time (0:00) showing on the game clock. American football typically only sees a play start with no time on the clock when a defensive penalty occurs during the last play of the period and the penalty is not declined (or, in the NFL, in the very rare circumstance when a team takes a fair catch as time expires and elects a free kick).[citation needed] Additionally, any period in Canadian football cannot end on a penalty (this is not the case in American football), so any penalty that occurs with 0:00 left in Canada extends the period by at least one more play.

tag: ul

text: These timing differences, combined with the fewer downs available for the Canadian offence to earn a first down, lead to spectacularly different end-games if the team leading the game has the ball. In American football, if the other team is out of time-outs, it is possible to run slightly more than 120 seconds (two minutes) off the clock without gaining a first down. In Canadian football, just over 40 seconds can be run off.[citation needed]

text: Kicker advancing the ball[edit]

text: Canadian football retains much more liberal rules regarding recovery of the ball by members of the kicking team. On any kick, the kicker and any member of the kicker's team behind the kicker at the time of the kick may recover and advance the ball. On a kickoff, since every member of the kicking team must be behind the ball when it is kicked, this effectively makes all twelve players "onside" and eligible to recover the kick, once it has gone ten yards downfield. On a punt or missed field goal, usually only the kicker is onside, as no one is behind the kicker. All of the players offside at the time of the kick may neither touch the ball nor be within five yards of the member of the receiving team who fields the kick; violation of this rule is a penalty for no yards. The penalty for no yards is 15 yards if the kick is in flight and 5 yards if it has been grounded.[citation needed]

text: The American rules are similar for the recovery of kickoffs. Any member of the kicking team may recover the ball once it has touched an opponent or once it has gone ten yards downfield and touched the ground. The ball is dead when recovered, though the kicking team is awarded possession at the spot of recovery.[citation needed]

text: The American rules differ from the Canadian ones for scrimmage kicks. In American rules to recover a scrimmage kick (punt or missed field goal) and retain possession, the ball must be touched beyond the line of scrimmage by a member of the receiving team (defense). If the ball is touched by the receiving team and then recovered by the kicking team, the kicking team will retain possession and be awarded a first down. If the receiving team has not touched the ball before the kicking team touches it, it is first touching as described above in fair catches and punt returns.[citation needed]

text:
Additionally, members of the kicking team must allow the receiving team the opportunity to catch a scrimmage kick in flight. There is no required distance; the NCAA revoked its rule of a 2-yard halo.[19]
Once the scrimmage kick has touched the ground, the kicking team is free to recover, subject to the first touching rules.

text: In both codes, a scrimmage kick which is blocked and recovered by the kicking team behind the line of scrimmage is in play. The kicking team may then choose to either attempt another kick or try to advance the ball, however no turnover has taken place on the play (unless a member of the receiving team has control of the ball), and therefore, the kicking team either has to advance the ball to the first down marker, or loses the down, which often results in a turnover on downs.[citation needed]

text: Blocking receivers[edit]

text: Under Canadian rules, the defensive line can only hold up or block a receiver within one yard of the scrimmage lines. In the NFL, contact up to five yards from the line is allowed. This allows for more open plays in Canadian football.[citation needed]

text: Fumbles out of bounds[edit]

text: In Canadian play, if the ball is fumbled out of bounds, the play ends with possession going to the team to last contact the ball in bounds (after the ball has completely left the possession of the fumbling ball carrier). A loose ball may be kicked forward (dribbled) provided it is then recovered by a player who is onside at the time of said kick. The ball may not, however, be intentionally kicked out of bounds to gain possession, this is then treated as a scrimmage kick out of bounds and possession goes to the opposing team. Incidental contact with the foot does not count as kicking the ball out of bounds. In American play, when a ball is fumbled out of bounds, the last team to have clear possession of the football is awarded possession, unless the ball goes out of the back or side of the end zone.

text: A team may still lose possession after a fumble out of bounds if the fumble occurred on fourth down (third down in Canadian play) and the ball becomes dead short of the line to gain. Because of plays like the Holy Roller, the NFL changed its rule regarding advancing a fumbled ball on offense. If the offensive team fumbles in the last two minutes of either half, or on fourth down at any time, only the player who fumbled is allowed to advance the ball past the point of the fumble. If any other offensive player advances the ball toward the opponent's goal line, the ball is moved back to the spot of the fumble, and the defensive team gains possession on downs unless the ball is recovered behind the spot of the fumble.

text: Field goals, singles, and touchbacks[edit]

text: In Canadian football any kick that goes into the end zone is a live ball, except for a successful field goal or if the goalposts are hit while the ball is in flight. If the player receiving the kick fails to return it out of the end zone, or (except on a kickoff) if the ball was kicked through the end zone, then the kicking team scores a single point (rouge), and the returning team scrimmages from its 35-yard line or, if the rouge is scored as a result of a missed field goal attempt, the receiving team may choose the last point of scrimmage. If a kickoff goes through the end zone without a player touching it or a kicked ball in flight hits a post without scoring a field goal, there is no score, and the receiving team scrimmages from its 25-yard line. If the kick is returned out of the end zone, the receiving team next scrimmages from the place that was reached (or if they reach the opponents' goal line, they score a touchdown); in the amateur levels of the game, they are given the ball at their 20-yard line if the kick was not returned that far.[20]

text: Singles do not exist in American football; however, only one point is counted when a safety is scored during a conversion attempt, in contrast to the two points scored on other safeties.[citation needed]

text: American football also allows a defending team to advance a missed field goal; however, because of the absence of singles and the goalpost position at the back of the end zone, the return is rarely exercised, except on a blocked kick, or as time expires in the half or in the game (with the most famous recent example being Chris Davis' game-ending return of a missed field goal for the winning touchdown in the 2013 Alabama–Auburn game). Most teams instead elect not to attempt a return and assume possession  – at the previous line of scrimmage in the NCAA and at the spot of the kick in the NFL. Since the goalpost is out of bounds, any non-scoring kick that strikes the goalpost is dead, and the receiving team takes over possession from the spot of the kick or their own 20-yard line, whichever is further from the receiving team's goal. Likewise, any kickoff or punt which either is kicked through the end zone, is kicked into the end zone and rolls out of bounds (without being touched by a player), is touched in the end zone by a member of the kicking team (with no member of the receiving team having touched it), or is downed in the end zone by a member of the receiving team, results in a touchback – the receiving team is awarded possession on their own 20-yard line. If a player of the receiving team fields a kickoff or punt in the end zone, he has the option to down it in the end zone (resulting in a touchback) or to try and advance the ball.[citation needed]

text: Following a successful field goal, in Canadian rules, the team scored upon has the option of receiving a kickoff, kicking off from its 35-yard line, or scrimmaging at its own 35-yard line (the CFL first instituted this rule in 1975, but eliminated this last option for the 2009 season, but it was reinstated for 2010). In American football, there is a kickoff by the scoring team after every score, with the exception of safeties (see below). The option for the scored-upon team to kick off after a touchdown exists in American amateur football, but it is very rarely exercised.[citation needed]

text: Open-field kick[edit]

text: Canadian football retains the open-field kick as a legal play, allowing a kick to be taken from anywhere on the field. The open-field kick may be used as a desperation last play by the offense: realizing they are unable to go the length of the field, they advance part of the way and attempt a drop kick, trying to score a field goal, or recover the ball in the end zone for a touchdown.[21]

text: Conversely, the defence, facing a last-second field goal attempt in a tie game or game they lead by one point, will often position its punter and place-kicker in the end zone. If the field goal is missed, they can punt the ball back into the field of play and not concede a single. Multiple such kicks may be attempted on the same play. During the October 29, 2010, Toronto Argonauts game against the Montreal Alouettes, four kicks occurred in one play: after a Montreal missed field goal, the Argonauts punted from the end zone to about the 20-yard line. The ball was caught and immediately punted back to the end zone by Montreal to attempt a single, and finally the Argos punted but failed to kick it out of the end zone, where the Alouettes recovered it for a touchdown.[22] [23]

text: American football only allows free kicks and scrimmage kicks made from behind the line of scrimmage; any kick beyond the line of scrimmage or after change of possession would result in a penalty.  (Some levels of American football allow the rare fair catch kick, which according to the NFL rules is neither a free kick nor scrimmage kick, but sui generis.)[citation needed]

text: Safeties[edit]

text: In both American and Canadian football, a safety (or safety touch) awards 2 points to the defending team if the offensive team is brought down in their end zone. In American football, the team giving up the safety must take a free kick from their own 20-yard line. In Canadian football, the team being awarded the 2 points has the option of scrimmaging from their own 35-yard line, kicking the ball off from their own 35-yard line, or having the opposing team kick off the ball from their own 35-yard line. In 2009, the CFL changed the latter option to be a kick-off from their own 25-yard line.[24]

text: Points after touchdown[edit]

text: In both games, after a touchdown is scored, the scoring team may then attempt one play for additional points. In Canadian football, this play is called a convert, and in American football, it is formally called a try, although it is more commonly referred to as either a conversion, extra point, or point after touchdown (PAT).   The additional points may be earned through a kick or a play from scrimmage. If done via kick, the scoring team gains one point, and if done from a scrimmage, the scoring team gains two.[citation needed]

text: However, the position of the ball for attempts is different in the two games. Point-after-touchdown attempts are snapped from the following points (as of the 2015 season):.[citation needed]

text:
NFL: 15-yard line for placekick attempts, 2-yard line for two-point conversion attempts.
Amateur American football (all levels): 3-yard line for all attempts
CFL: 25-yard line for placekick attempts, 3-yard line for two-point conversion attempts.
Amateur Canadian football (all levels): 5-yard line for all attempts.

text: Because the goalposts are on the goal line in Canada and the end line in the United States, a CFL kicker is at the same distance from the goalposts as an NFL kicker. Before the 2015 CFL season, that league used the 5-yard line for all attempts, which meant that the Canadian kicker was closer to the goal posts than an American kicker at any level. Amateur Canadian kickers remain closer to their goal posts than their American counterparts.[citation needed]

text: According to the rules of both the NFL and NCAA, on conversion attempts, the ball will automatically be spotted in the middle of the field at the appropriate scrimmage line unless a member of the kicking team expressly asks a referee for an alternative placement. Per the rules, the ball can be placed at another spot between the hash marks (especially for strategic positioning on a 2-point conversion attempt) or at another spot further back from the 2-, 3-, or 15-yard line (not uncommon at lower levels of football, since as the season progresses, conditions may worsen toward the center of the field, especially at the spot from which the PAT is usually kicked; the kicker may thus request a spot where the footing is surer).[citation needed]

text: During conversions, the ball is considered live in the CFL, American collegiate football, some high school associations, the now-defunct NFL Europa, and starting with the 2015 season the NFL itself. As such, this allows the defensive team to gain two points on an interception or fumble return should they reach the kicking team's end zone, or (in the CFL) one point should the defensive team make an open-field drop kick through the kicking team's goalposts. Conversely, in other levels of American football and amateur Canadian football, defensive teams cannot score during a try attempt.[citation needed]

text: Runner down[edit]

text: In Canadian amateur football, the ball is not dead if a player kneels momentarily to, and does, recover a rolling snap, onside/lateral pass, or opponent's kick, while in American amateur football, such a situation produces a dead ball, unless the player is the holder for a place kick. The holder is allowed to catch the snap or recover a rolling snap while on a knee to hold the kick and may also rise to catch a high snap and immediately return to a knee.[citation needed]

text: At professional levels in both games, unless it is a clearly willful kneel or slide by a ball carrier to go down, a player must be touched while on the ground, otherwise, the player may stand up and continue to advance the ball. Hitting a player who is kneeling, sliding, or clearly intends to run the ball out of bounds (especially quarterbacks) is generally viewed as unsportsmanlike and is often penalized, and in the most blatant of cases (especially if it happens in the dying seconds of a game), the player may be subject to off-field disciplinary action by their respective league governing body, usually in the form of fines or suspensions.[citation needed]

text: Overtime[edit]

text: The procedures to settle games that are tied at the end of regulation vary considerably among football leagues.

text: Most leagues other than the NFL, including the CFL, use a procedure frequently called the "Kansas Playoff", so named because it was first developed for high school football in that state. The rules are summarized here:[citation needed]

text:
A coin toss at the start of overtime determines the team that first receives possession in overtime, and which end zone will be used.
Each team in turn receives one possession starting with first-and-10 at a fixed point on the field, which varies according to league:
US college: Opponent's 25-yard line.
US high school (also British Columbia, where high schools play under American rules): Standard rules call for the opponent's 10-yard line, but state/provincial associations are free to use different yardage.
CFL: Opponent's 35-yard line.
The game clock does not run, but the play clock is enforced.
At all levels, possessions end when the offensive team scores, misses a field goal, or turns the ball over. Touchdowns are followed by a conversion attempt, with the following additional caveats:
US college: Teams must attempt a two-point conversion starting with the third overtime procedure.
CFL: A convert kick is not allowed in overtime—all conversion attempts must be scrimmage plays (i.e., two-point attempts).
US and BC high school: Standard rules call for no restrictions on the type of conversion attempt, but some state/provincial associations may limit the use of kick tries.
Ability of defensive team to score after gaining possession on a turnover:
US college and CFL: Can advance the ball upon gaining possession; if it scores a touchdown, it will satisfy the condition of each team having a chance to score and thus end the game.
US and BC high school: Possession ends immediately under standard rules. Exceptions to this rule are in Massachusetts and Texas, where the base rule set is that of the NCAA.
Each team receives one charged timeout per overtime procedure except in the CFL, which allows no timeouts in overtime.
If the score remains tied at the end of an overtime procedure, another procedure follows (except as noted below), with the team that had the second possession in the previous procedure having the first possession of the next procedure.
Limit on number of overtime procedures:
US college and high school: No limit; procedures continue until a winner is decided.
CFL: In regular season games, maximum of two procedures, with the game declared a tie if it remains level. In postseason games, procedures continue until a winner is decided.

text: The NFL overtime is a modified sudden-death period of 15 minutes, for playoff games only; since the 2017 season, overtime periods in the preseason and regular season are 10 minutes, as part of an overall effort by the NFL to speed up games and reduce their length. If the team that receives the opening kickoff scores a touchdown, or the defensive team scores a safety, the game ends at that point. If the receiving team scores a field goal, the game continues with the scoring team kicking off, and the scored-upon team having a chance at possession. If that team scores a touchdown, or loses possession, the game ends; if it scores a field goal, overtime continues, with the next score by either team ending the game. In the regular season, if a game remains tied after the 10-minute period, it is declared a tie. In postseason games, there are multiple 15-minute periods until a winner is decided.[citation needed]

text: Other differences[edit]

text: In American high school and college football, as well as all Canadian football, receivers need only have one foot in bounds for a catch to count as a reception. NFL play requires two feet in bounds and, up through the 2007 season, an NFL official could also award a catch if it was judged that the receiver would have come down in bounds if he had not been pushed by a defender. This rule was based on a judgment call by the official, and was criticized for being inconsistent. The rule was dropped prior to the 2008 season by the NFL.[25]

text:
In Canadian football, defensive pass interference may be called on any legal forward pass, even when the receiver is behind the line of scrimmage. Pass interference rules in all levels of American football do not apply until the thrown ball crosses the neutral zone.
Until 2010, when a forward pass was deemed to be "uncatchable", defensive interference with the intended receiver was penalized in Canadian football. This rule was dropped for 2010, bringing it in line with long-standing practice in American college and professional football.

text: CFL roster sizes are 46 players (rather than 53 as in the NFL, though only 45 will dress for a game). A CFL team may dress up to 44 players comprising 21 non-imports (essentially, Canadians), 20 imports (almost exclusively Americans), and 3 quarterbacks.[26]

text: The traditional NFL football season runs from the 2nd week of September until late December or the start of January, with the NFL playoffs occurring in January and February. In contrast, the CFL regular season runs from late June to late October. This is in order to ensure the Grey Cup playoffs can be completed in mid-November, before the harsh Canadian winters set in. This is an important consideration for a sport played in outdoor venues in locations such as Regina, Saskatchewan; Toronto, Ontario; Hamilton, Ontario; Calgary, Alberta; Edmonton, Alberta; Winnipeg, Manitoba and Montreal, Quebec.

text: Officials' penalty flags used in the CFL are orange in color. In American football, officials typically use yellow penalty flags. Conversely, coaches' challenge flags for replays are yellow in the CFL as opposed to red in the NFL. Further, in the CFL, the referee wears a black cap with white piping, and the other officials wear white caps with black piping. In American leagues, the referee wears a solid white cap, and the other officials wear black with white piping.[26]

text: Additionally, when announcing penalties, in American football, the penalized team is announced using generic terms ("offense"/"defense", for example), but in Canadian football (especially the CFL) the penalized team is announced by their respective city or province.

text: Strategic and tactical differences[edit]

text: Although the rules of Canadian and American football have similarities, the differences have a great effect on how teams play and are managed. Generally, the "big play" is more important in the Canadian game, and offensive series are more difficult to manage.[citation needed]

text: Red-zone management[edit]

text: The red zone is an unofficial designating the portion of the field between the 20-yard line and the goal line. Due to the goalposts' being on the goal line in Canadian football, teams must avoid hitting the goalposts. Thus most touchdown throws are aimed away from the centre portion of the end zone. In the CFL, the goalposts have the same construction as the NFL posts, with the centre post being about 2 yards deep in the end zone. It is extremely rare for CFL passes to hit any part of the posts. When this occurs, a dead ball results. Occasionally, receivers can use the post to good effect in a 'rub' play to shed a defender. End zone passing becomes even more complicated when the corners of the end zone are truncated, as is the case at stadia where the field is bounded by a running track. However, the offensive team enjoys a counteracting advantage of end zones more than twice the size of those in American football (20 yards with a wider field), significantly expanding the area that must be covered by the defensive team and also allowing the freedom to run some pass patterns not available in American football's red zone. Moreover, the rule requiring only a single foot to be in bounds upon pass reception in Canadian football further stretches the amount of area that the offenses have to work with. NFL offenses generally try a run between tackles when on the one-yard line.  CFL offenses make similar attempts on first down on the one-yard line, but second and third down attempts, if required, can be much more varied than their NFL counterparts.[citation needed]

text: Special teams[edit]

text: The frequency of punts is highly dependent upon the success, or lack thereof, of the offense. Punt returns are ubiquitous in Canadian football because the "no-yards" rule permits virtually every punt to be fielded and returned. Moreover, if the kicking team punts the ball out of bounds in an attempt to forestall a return and the ball goes out of bounds between the two 20-yard lines without touching the ground first, a 10-yard penalty is assessed and the ball advanced from where it left play, or the kicking team is backed up 10 yards and must replay the down.[27]  "Shanked" punts are therefore extremely costly to the kicking team. Though missed field goals may be returned in both national rule sets, the deeper end zone and goal post positioning make this much more common in Canadian rules. TSN on-air analysts state that they are the single play-from-scrimmage most likely to result in a touchdown. This set of special teams play (field goal return units) are rare in the American game to the point where a returner is not a standard part of a defensive field goal unit and will only be seen in unusual circumstances, with one especially notable example being the famous "Kick Six" college football game in 2013. Canadian kickoffs rarely result in a touchback, so special teams are more prominent in that area of the game as well. The difference in the games' final minutes procedures make comebacks — and the need for an onside kick 'hands' team, more prominent as well. The rule regarding last touch of the ball before leaving the play of field, rather than American football's last possession rule, makes the onside kick more likely to be successful as well. The most complex coaching job in Canadian football is said[by whom?] to be that of special teams co-ordinator. As many as 40 of a CFL roster of players may have a special teams role because of the wide variety of possible situations. In 2014 and 2015, the Edmonton Eskimos even used their third-string quarterbacks (Pat White in 2014 and Jordan Lynch in 2015[28]) as part of their kick and kick-coverage teams. This is highly unusual, as quarterbacks are generally discouraged from making contact plays. Kick returning was a duty generally handled by a player with another role, such as receiver or defensive back. Henry "The Gizmo" Williams[29] was the first player designated by telecasts as "KR" for a kicker returner position as his duties were almost entirely for that role, and referring to him as "WR" for wide receiver was increasingly seen as anachronistic. By far the greatest kick returner in professional football history, Gizmo Williams had more returns for touchdowns called back for infractions than any other player has ever scored (28 — 26 punts, 2 kick-offs).  No NFL player has enjoyed similar success and the careers of such specialists (like Devin Hester) come nowhere near to matching the impact on the game that such players have in the CFL.[citation needed]

text: Management of offensive drives[edit]

text:
Having three downs on a much longer and wider field with unlimited backfield motion results in Canadian teams requiring faster, more nimble athletes (comparatively) than their American counterparts. Paradoxically, this makes Canadian defense better at defending rushing plays. Rushing plays tend to be unlikely to produce a full ten yard gain, and if correctly anticipated by the defense, much gain at all. The fewer downs means that an unsuccessful rushing play leaves an offense to have a single play to make comparatively longer first down yardage, so rushing plays are less-favored unless the team on offense is actively managing the clock while maintaining the lead. Pundits often like to claim that a Canadian team that rushes for 100 yards or more per game is likely to win, but the reality is winning teams rush the ball in defense of their leads, and not as a tactic to produce drives that lead to points unless they are markedly superior to their opponents. The larger field generally permits greater YAC (yards after catch) on each individual catch, where the NFL produces passing plays where there are either very few YAC yards (immediate tackle) or huge YAC yards (missed tackle or broken coverage for huge gains.)  For this reason, Canadian teams usually prefer passing over rushing to a greater extent than American, since pass attempts generally tend to gain more yards than rushing. Offensive drives (continuous possession of the ball) tend to be shorter. Long drives of half a quarter or more are common in American football but rare in Canadian.[citation needed]
In theory, an NFL team taking possession on their own one-yard line, using three downs for each first-down conversion and the full 40 second clock could run 27 plays and consume a full 18 minutes of clock time covering the 99 yards. A CFL team doing something similar (two plays per conversion, 20 second clock, average 10 seconds of clock time while the officials reset the ball between plays, 109 yards) would run 24 plays and consume 12 minutes of clock at the most. Typical drive lengths in practice reflect this theoretical difference.[citation needed]

text: One other notable difference is the propensity of CFL quarterbacks to rush the ball, both by design and as a result of reacting to the defense. Damon Allen[30] (the younger brother of Pro Football Hall of Fame running back Marcus Allen) had 11,920 rushing yards to go along with 72,381 passing yards in his 23-year career and actually sits third overall in career rushing yards. Contrast that will Randall Cunnigham's 4928 yards over 16 seasons.[31] 1000 yard rushing seasons for CFL quarterbacks have occurred,[32] and 400+ yard seasons for playoff bound teams' starting quarterbacks, if they remain healthy for the entire schedule, are not unusual.[citation needed]

text: Backfield motion[edit]

text: Perhaps the greatest difference arises due to the virtually unlimited movement allowed in the defensive and offensive backfields on a play from scrimmage in the Canadian game vs. very restricted offensive movement in the American game. Combined with the much larger field size, this difference changes the skillsets required of the athletes. Canadian wide receivers, safeties and cornerbacks are far enough from the point where the ball is snapped that they rarely participate in rush offense or defense. Linebackers can be called upon to successfully defend running backs sent to receive passes. There is therefore a much greater premium placed on athletic speed, with former Edmonton Eskimos GM and former wide receiver Ed Hervey (6 ft 0 in [183 cm], 195 lb [88 kg], All-American at USC in the 200 meter) and Malcolm Frank[30] (5 ft 8 in [173 cm] 170 lb [77 kg]) being prototypical for the CFL. The offence has many more formation options and starting positions, forcing the defence to anticipate more possibilities. Seven of the 12 men on a CFL offense (typically the five linemen and the wide receivers) must be at the line of scrimmage at the time of the snap, and the other five must be at least one yard behind the line. Only the quarterback and linemen must be motionless at the time of the snap, allowing up to six players to be moving toward or along the line at varying speeds (typically the wide receivers are still or at a walking pace at the snap to ensure they are at the line of scrimmage.)[citation needed]

text: Late comebacks[edit]

text: In both the college and pro games, an offensive team with the lead has more difficulty in running out the clock in the Canadian game. In the Canadian Football League, the clock is stopped while the officials place the ball, and then they whistle the game clock and play clock to begin in the last minutes of a half; whereas in the National Football League the clock remains running while the officials set the ball (dependent upon the result of the previous play—penalty, incomplete pass, out-of-bounds, or tackle inbounds in both leagues) while the play clock of 40 seconds runs down. The game clock only begins again when the play is whistled in, for an inbounds tackle, or at the snap of the ball for the other outcomes in the CFL. A team that is ahead has one fewer opportunity to kill clock time in the Canadian game with three downs, and can only take the play clock time (20 seconds) and the length of the play itself off the clock with each down. After the three-minute warning, a penalty of a loss of down (on first and second down, 10 yards on third down) results for failing to start the new play in time (time count violation). Additionally, if a Canadian team commits a time count violation on third down, the referee has the right to require that it legally start a new play before the play clock expires, and can award possession to the defending team if another time count is committed. If a team that is trailing in the CFL can begin to produce two-and-outs on defense and efficient scoring drives on offense, 14 and even 17 points can be successfully scored in the final three minutes. This comeback proclivity is so pronounced that the CFL uses it for marketing purposes: No Lead Is Safe.[33]