"As we all know, Gray wolves seek out large hoofed browsers such as elk, moose, bison, deer and caribou".............."A healthy set of teeth is essential for these predators to kill, eat and defend themselves"........ "As a result, they tend to avoid biting down on tough body parts, such as bones, so that their teeth do not break"............"Broken teeth cannot heal, so carnivores are not going to chew on bones and risk breaking their teeth unless they have to"................"If food becomes scarce however, the wolves may resort to consuming bones, eating more of the carcasses, leading to more damaged teeth".............."It is therefore possible to assess the food levels available to existing wolf populations based on how many broken teeth the animals have".............What must also be factored in to this analysis is the age of the Wolf pack members, as older individuals are also more likely to have more damaged teeth"

https://www.sciencedaily.com/releases/2019/09/190924143158.htm

Date:

September 24, 2019

Source:

University of California - Los Angeles

What wolves' broken teeth reveal about their lives

Biologist links an increase in fractured teeth to a dwindling supply of prey

UCLA evolutionary biologist Blaire Van Valkenburgh has spent more than three decades studying the skulls of many species of large carnivores -- including wolves, lions and tigers -- that lived from 50,000 years ago to the present. She reports today in the journal eLife the answer to a puzzling question.

Essential to the survival of these carnivores is their teeth, which are used for securing their prey and chewing it, yet large numbers of these animals have broken teeth. Why is that, and what can we learn from it?

In the research, Van Valkenburgh reports a strong link between an increase in broken teeth and a decline in the amount of available food, as large carnivores work harder to catch dwindling numbers of prey, and eat more of it, down to the bones.

"Broken teeth cannot heal, so most of the time, carnivores are not going to chew on bones and risk breaking their teeth unless they have to," said Van Valkenburgh, a UCLA distinguished professor of ecology and evolutionary biology, who holds the Donald R. Dickey Chair in Vertebrate Biology.

For the new research, Van Valkenburgh studied the skulls of gray wolves -- 160 skulls of adult wolves housed in the Yellowstone Heritage and Research Center in Montana; 64 adult wolf skulls from Isle Royale National Park in Lake Superior that are housed at Michigan Technological University; and 94 skulls from Scandinavia, collected between 1998 and 2010, housed in the Swedish Royal Museum of Natural History in Stockholm. She compared these with the skulls of 223 wolves that died between 1874 and 1952, from Alaska, Texas, New Mexico, Idaho and Canada.

Yellowstone had no wolves, Van Valkenburgh said, between the 1920s and 1995, when 31 gray wolves were brought to the national park from British Columbia. About 100 wolves have lived in Yellowstone for more than a decade, she said.

In Yellowstone, more than 90% of the wolves' prey are elk. The ratio of elk to wolves has declined sharply, from more than 600-to-1 when wolves were brought back to the national park to about 100-to-1 more recently.

In the first 10 years after the reintroduction, the wolves did not break their teeth much and did not eat the elk completely, Van Valkenburgh reports. In the following 10 years, as the number of elk declined, the wolves ate more of the elk's body, and the number of broken teeth doubled, including the larger teeth wolves use when hunting and chewing.

The pattern was similar in the island park of Isle Royale. There, the wolves' prey are primarily adult moose, but moose numbers are low and their large size makes them difficult to capture and kill. Isle Royale wolves had high frequencies of broken and heavily worn teeth, reflecting the fact that they consumed about 90% of the bodies of the moose they killed.

Scandinavian wolves presented a different story. The ratio of moose to wolves is nearly 500-to-1 in Scandinavia and only 55-to-1 in Isle Royale, and, consistent with Van Valkenburgh's hypothesis, Scandinavian wolves consumed less of the moose they killed (about 70%) than Isle Royale wolves. Van Valkenburgh did not find many broken teeth among the Scandinavian wolves. "The wolves could find moose easily, not eat the bones, and move on," she said.

Van Valkenburgh believes her findings apply beyond gray wolves, which are well-studied, to other large carnivores, such as lions, tigers and bears.

Extremely high rates of broken teeth have been recorded for large carnivores -- such as lions, dire wolves and saber-toothed cats -- from the Pleistocene epoch, dating back tens of thousands of years, compared with their modern counterparts, Van Valkenburgh said. Rates of broken teeth from animals at the La Brea Tar Pits were two to four times higher than in modern animals, she and colleagues reported in the journal Science in the 1990s.

"Our new study suggests that the cause of this tooth fracture may have been more intense competition for food in the past than in present large carnivore communities," Van Valkenburgh said.

She and colleagues reported in 2015 that violent attacks by packs of some of the world's largest carnivores -- including lions much larger than those of today and saber-toothed cats -- went a long way toward shaping ecosystems during the Pleistocene.

In a 2016 article in the journal BioScience, Van Valkenburgh and more than 40 other wildlife experts wrote that preventing the extinction of lions, tigers, wolves, bears, elephants and the world's other largest mammals will require bold political action and financial commitments from nations worldwide.

Discussing the new study, she said, "We want to understand the factors that increase mortality in large carnivores that, in many cases, are near extinction. Getting good information on that is difficult. Studying tooth fracture is one way to do so, and can reveal changing levels of food stress in big carnivores."

The research was funded by the National Science Foundation and National Park Service.

Journal Reference:

1. Blaire Van Valkenburgh, Rolf O Peterson, Douglas W Smith, Daniel R Stahler, John A Vucetich. Tooth fracture frequency in gray wolves reflects prey availability. eLife, 2019; 8 DOI: 10.7554/eLife.48628

"A new study finds US and Canada have lost more than 1 in 4 birds in the past 50 years"............. "Hardest hit are sparrows, warblers, finches, and swallows who are critical in ecosystem seed dispersal and pest control"............"The major factor driving these declines is loss and degradation of habitat, due to agricultural intensification and urbanization"..........."Other bird-killers include domestic cats; collisions with glass, buildings, windmills and solar farms, deforestation and pesticides"

https://phys.org/news/2019-09-canada-lost-birds-years.html

New study finds US and Canada have lost more than 1 in 4 birds in the past 50 years

by Cornell University; 9/19/19

A study published today in the journal Science reveals that since 1970, bird populations in the United States and Canada have declined by 29 percent, or almost 3 billion birds, signaling a widespread ecological crisis. The results show tremendous losses across diverse groups of birds and habitats—from iconic songsters such as meadowlarks to long-distance migrants such as swallows and backyard birds including sparrows.

Multiple, independent lines of evidence show a massive reduction in the abundance of birds," said Ken Rosenberg, the study's lead author and a senior scientist at the Cornell Lab of Ornithology and American Bird Conservancy. "We expected to see continuing declines of threatened species. But for the first time, the results also showed pervasive losses among common birds across all habitats, including backyard birds."

The study notes that birds are indicators of environmental health, signaling that natural systems across the U.S. and Canada are now being so severely impacted by human activities that they no longer support the same robust wildlife populations.

The findings showed that of nearly 3 billion birds lost, 90 percent belong to 12 bird families, including sparrows, warblers, finches, and swallows—common, widespread species that play influential roles in food webs and ecosystem functioning, from seed dispersal to pest control.

Among the steep declines noted:

• Grassland birds are especially hard hit, with a 53 percent reduction in population—more than 720 million birds—since 1970.
• Shorebirds, most of which frequent sensitive coastal habitats, were already at dangerously low numbers and have lost more than one-third of their population.
• The volume of spring migration, measured by radar in the night skies, has dropped by 14 percent in just the past decade.
• the largest factor driving these declines is likely the widespread loss and degradation of habitat, especially due to agricultural intensification and urbanization.
• Other studies have documented mortality from predation by free-roaming domestic cats; collisions with glass, buildings, and other structures; and pervasive use of pesticides associated with widespread declines in insects, an essential food source for birds. Climate change is expected to compound these challenges by altering habitats and threatening plant communities that birds need to survive. More research is needed to pinpoint primary causes for declines in individual species.

• The study also documents a few promising rebounds resulting from galvanized human efforts. Waterfowl (ducks, geese, and swans) have made a remarkable recovery over the past 50 years, made possible by investments in conservation by hunters and billions of dollars of government funding for wetland protection and restoration. Raptors such as the Bald Eagle have also made spectacular comebacks since the 1970s, after the harmful pesticide DDT was banned and recovery efforts through endangered species legislation in the U.S. and Canada provided critical protection.
  "It's a wake-up call that we've lost more than a quarter of our birds in the U.S. and Canada," said coauthor Adam Smith from Environment and Climate Change Canada. "But the crisis reaches far beyond our individual borders. Many of the birds that breed in Canadian backyards migrate through or spend the winter in the U.S. and places farther south—from Mexico and the Caribbean to Central and South America. What our birds need now is an historic, hemispheric effort that unites people and organizations with one common goal: bringing our birds back."
• More information: K.V. Rosenberg el al., "Decline of the North American avifauna," Science (2019). science.sciencemag.org/lookup/ … 1126/science.aaw1313

  Journal information: Science 

As we have reviewed many times in the past, research has revealed that hunting cougars or thinning their numbers as a method of wildlife management can actually increase the number of young male cats on the landscape, upping the likelihood of those inexperienced felids getting into conflicts with people and livestock"..................Reiterating this finding-----“There is evidence that densities of young, dispersing cougars are likely to be comparatively high where local densities of resident adults have been depressed by hunting, as long as other nearby and less-heavily exploited areas serve as sources of dispersers from other meta-populations".................."Under such a scenario, heavy localized hunting of older cougars could increase rather than reduce exposure of people to close-threatening encounters with cougars".............."Additionally, sport hunting of cougars to benefit wild ungulate populations is not supported by the scientific literature"..............…"Any effort to control cougars should be part of an effort that addresses all factors impacting the ungulate population"..............."Finally, the odds of increased complaints and livestock depredations increased dramatically (36% to 240%) with increased cougar harvest"

https://www.google.com/url?rct=j&sa=t&url=https://www.boulderweekly.com/news/are-state-actions-increasing-the-risk-of-cougars-attacking-people/&ct=ga&cd=CAEYBCoUMTQ1Mzk4NDc2OTIzNjQ4NzEyNTYyGjQzMDgzYjIxMTY2OGE5NzA6Y29tOmVuOlVT&usg=AFQjCNHyzLIPdxnP8l1KWlt-x96MDlz07w

Are state actions increasing the risk of cougars attacking people?

By

 Rico Moore

 -

 September 12, 2019

Mark Elbroch-credit all pictures below

Orca Killer Whales from the Eastern Tropical Pacific Ocean are rarely spotted off of the southern California coast............But this summer, a pod of the Orca's were seen first hand chasing and getting a dolphin calf meal for their efforts..........Like a pack of Wolves on land, Killer whales are among the world's fastest-moving marine mammals"............."They are capable of clocking speeds over 30 miles (48 kilometres) per hour (an impressive feat when you consider that they can weigh up to 11 tons!)".............."The black-and-white predators are armed with a mouth full of large, interlocking teeth and are highly intelligent and social – which makes them particularly efficient hunters"..........."When it comes to elusive and agile common dolphins, the hunt often sees killer whales teaming up in a coordinated attack and pursuing their quarry at high speed".............Click the link below to witness first hand the teamwork and persistence of Orca Whale pods

https://www.earthtouchnews.com/natural-world/predator-vs-prey/incredible-aerial-footage-shows-orcas-hunting-down-a-dolphin

Orca Whales hunting Dolphins(video-click to view)
https://youtu.be/IZTSd-CMEno

Incredible aerial footage shows orcas hunting down a dolphin

Incredible aerial footage shows orcas hunting down a dolphin

BY EARTH TOUCH NEWS AUGUST 06 2019Whale watchers off the coast of Orange County recently witnessed firsthand the hunting prowess of killer whales when a pod, believed to belong to a population from the Eastern Tropical Pacific that is rarely seen in waters around California, dispatched a dolphin calf after a high-speed chase. Photographer Matt Larmand witnessed the hunt from a Dana Wharf Whale Watching boat and used a drone to capture amazing aerial footage of the actionOrca with its Dolphin catch

The orcas were initially spotted cruising up the coast towards Orange County, but things heated up when they narrowed in on a pod of common dolphins. "It was surprising to me with what persistence they chased this dolphin pod,” Newport Coastal Adventure owner Ryan Lawler told The Mercury News. "They chased it for two miles at a constant pace – like wolves chasing down their prey, trying to tire their prey out."

Killer whales are among the world's fastest-moving marine mammals, capable of clocking speeds over 30 miles (48 kilometres) per hour (an impressive feat when you consider that they can weigh up to 11 tons!). The black-and-white predators are armed with a mouth full of large, interlocking teeth and are highly intelligent and social – which makes them particularly efficient killers.

For the moment, a Dolphin eluding an Orca

Hunting tactics are typically defined by what's on the menu: schools of fish are snared in a net of bubbles from below, while sharks are likely rammed and then their bodies torn open just below the pectoral fin so the orcas can hoover up their nutrient-rich livers. But when it comes to nippy and agile common dolphins, the hunt often sees killer whales teaming up in a coordinated attack and pursuing their quarry at high speed.

"They went after that [dolphin] baby. I guess that was an easier target," Larmand recalls. "They’d come from different directions, they were corralling it and getting it to go in the direction they wanted it to go. They knew exactly what they were doing and how to do it. It was crazy to watch."

A large pod of Orcas

Whale-watching guides and marine researchers identified the orcas as belonging to a group usually found in the Eastern Tropical Pacific (ETP) and – according to Alisa Schulman-Janiger, co-founder of the California Killer Whale Project – it's unusual to encounter them at this time of the year. ETPs usually hang out in waters off Mexico or Costa Rica and turn up occasionally in California from November through January when the water is a bit warmer, she explains.

Schulman-Janiger will be analysing photos in an attempt to identify the individuals, but she suspects that this group is not the same one that turned up in town late last year. Not much is known about ETP orcas, but marine mammals do seem to make up, at least, part of their diet.

"While rabbits, squirrels, and rodents make up the bulk of their prey, the 9-40 pound Bobcat is powerful enough to take down young deer and other ungulates, nimble enough to capture much smaller prey, including insects like grasshoppers"........."Because of both their abundance and their hunting prowess, the cats play an important role in their ecosystems, controlling the populations of a number of species that might otherwise go unchecked, including lyme disease and other tick-borne carrying rodents"............Comfortable enough around people to call suburbia home, below are pictures of a West Texas homeowner who allowed successive families of "Bobs" to make his porch home in 2017-18

https://www.earthtouchnews.com/natural-world/natural-world/bobcat-manor

Bobcat Manor

Earthtouch News August 27, 2019

Bobcat Manor

While Gray Wolves will and do kill Coyotes, famed Wolf researcher Paul Paquet studies in Manitoba, Canada revealed that "there was no evidence that Wolves actively searched for Coyotes to kill"..........."In the area where Paquet conducted his study, elk served as the major winter food for both wolves and coyotes"............"Wolves killed elk while coyotes scavenged the remains"............"In this regard, coyotes weren't dumb"............."As Paquet notes, "Because predation on [large prey] involves considerable risk of injury and is likely energetically expensive owing to a low rate of success, there is no apparent advantage in killing prey if good quality food can be scavenged"............Pacquet goes on to say: "If Wolves and Coyotes co-exist in a region where the smaller bodied deer is the main prey for both canids, "then coyotes lose the opportunity to scavenge wolf kills because wolves preying on deer leave few remains"........."In Montana, Researchers ERic Gese and Todd Atwood Atwood and Gese located 92 wolf kills (presumably elk and deer), 85 percent of which were visited by coyotes"............"They witnessed 36 conflicts, involving 6 different coyote packs and the Bear Trap wolf pack, at wolf-kill sites"............"Although coyotes gained possession of the contested carcass on 17 occasions, all such carcasses were already nearly depleted"............"During the course of study, wolves killed one adult coyote and 2 pups, whereas 3 adult coyotes were killed by cougars; all such mortalities occurred within 200 meters of a wolf-killed deer or elk"................Atwood and Gese concluded the following: "Coyotes do not perceive wolves as a threat requiring generalized spatial avoidance"..........."Rather, the threat of aggressive interactions with wolves is spatially discrete and primarily contained to areas adjacent to carrion resources"

by John Ozoga

May 01, 2012          

Gray Wolves will sometimes kill Coyotes 
                                that seek to scavenge their kill
                                
   click link toview video of this occurring in Yellowstone Park
    https://www.youtube.com/watch?v=YcFtdnewTCU

Can wolves and coyotes coexist?

As wolves disappeared in the past, coyotes quickly moved in to occupy the vacated range. Now, the reverse seems to be taking place; wolves are moving into reclaim range coyotes have occupied for the past 100 years or more.

Some biologists support the view that wolves will replace coyotes in certain areas. Others suggest the "clever coyote" will learn to coexist with wolves. There is scientific evidence to support both views.

The Isle Royale Story
Historically, wolves may have played an important role in replacing coyotes on Isle Royale, located at the west end of Lake Superior. In less than 60 short years, the coyote arrived on Isle Royale, prospered for a time, declined, then disappeared altogether.

According to the late Laurits Krefting, a long-time wildlife research biologist with the U.S. Bureau of Sport Fisheries and Wildlife, coyotes probably reached Isle Royale by traveling over the ice from the Sibley Peninsula region of Ontario, a distance of 15 miles, about 1906. (This is about the same time coyotes were first observed in Michigan's UP.) Despite the less than favorable habitat for them, coyotes flourished on the island, reaching peak numbers of about 150 animals, in 1948.

Krefting noticed that coyote numbers began to decline, starting in 1949, about the time Great Lakes Wolves(admix of Gray and Eastern Wolf) reached the island. The decrease in coyote numbers also came with a crash decline in the beaver population, a die-off of moose, a low snowshoe hare population and sustained human Trapper take. Coyotes disappeared from Isle Royale in 1957 or 1958.

"Even at its best," says Krefting, "the habitat on Isle Royale was marginal for coyotes. When strict fire protection was put into effect, the changes in plant succession gradually produced an even less favorable habitat. A reduced food supply and direct killing by wolves are the factors that probably contributed most to the coyote's disappearance. A combination of these and other factors plus the fact that it was an island situation probably was necessary to cause coyote extinction."

Coyote scavenging Wolf kill,,,,,,,,,,,,lean pickings

Hence, this may have been a rather unique situation. Certainly, the ecological nature of the island (i.e., dense conifers and lack of openings) is not what one would picture as coyote country. And, given its insular condition, the island undoubtedly lacks the diversity in flora and fauna characteristic of the adjacent mainland. This means there are few alternate prey for coyotes.


MANITOBA, CANADA

In Manitoba, Canada, researcher Ludwig Carbyn observed that Gray wolves frequently killed coyotes but did not eat them(same in Yellowstone after Wolf re-introduction in 1995). He found no evidence that coyotes avoided wolves during most of the year, but definitely did so from mid- to late-winter.

Carbyn theorized that differences in snow conditions, and learning on the coyote's part, may be involved in the coyotes changing response to wolves as the winter progressed. When snow is deep and soft, coyotes are hindered more than wolves. However, since coyotes often trailed wolves through deep soft snow, Carbyn rationalized although coyotes may avoid wolves after a "refractory period," they may actually trail them at a safe distance in search of food.

Wolves chasing down and killing a Coyote that sought
to scavenge their kill

Since wolves are territorial and may even kill their own kind when boundaries are trespassed, buffer zones exist between wolf territories where few wolves travel. Coyotes sometimes find these buffer zones safe havens. In Carbyn's study, coyotes were not always safe from wolves while in the buffer zone when wolf density was high. However, overall coyote survival appeared to be greater there during years of only moderate wolf density.

In another Manitoba study, Paul Paquet found coyotes scavenging wolf-killed deer within 24 hours after abandonment by wolves. Although wolves occasionally killed coyotes, Paquet saw no evidence of wolves actively searching for coyotes. Neither was there any evidence that coyotes adjusted their movements to avoid wolves.

In the area where Paquet conducted his study, elk served as the major winter food for both wolves and coyotes.  Wolves killed elk while coyotes scavenged the remains. In this regard, coyotes weren't dumb. As Paquet notes, "Because predation on [large prey] involves considerable risk of injury and is likely energetically expensive owing to a low rate of success, there is no apparent advantage in killing prey if good quality food can be scavenged."

This wolf-coyote relationship is interesting because the primary source of food was large prey, leaving enough food for both wolves and coyotes. However, it may be a different story when both predators must exist primarily upon smaller prey such as deer.


Coyote scavenging the few "leftovers" of a Wolf kill

"If deer are the preferred prey," notes Paquet, "then coyotes lose the opportunity to scavenge wolf kills because wolves preying on deer leave few remains."

Findings from studies conducted by Minnesota researcher Glen DelGuidice add a new twist to this story. Apparently, during especially severe winters (i.e., deep snow for four to eight weeks), wolves exhibit surplus killing of deer with no or low consumption of the carcass. Under such conditions wolves may kill many more deer than normal and benefit coyotes by leaving more for them to scavenge.

Recolonizing Wolves in Montana

One of the more recent investigations into coyote-wolf interactions was by Todd Atwood and Eric Gese. They conducted their work during the winters of 2003-04 and 2004-05, in northern Montana. This was shortly after wolves recolonized the region, presenting a unique opportunity to determine how naive coyotes adjust to the sudden presence of a competitively dominant canid that might threaten coyote survival in the region.

Atwood and Gese followed the activities of 29 radio-collared coyotes, belonging to 11 packs living within the 187 square mile home range of the Bear Trap wolf pack. Before pups were born, coyote pack size averaged 4 adults. Wolf pack size varied from 2 to 8 and averaged 5 individuals. In addition, the researchers followed nearly 1000 miles of coyote tracks and over 300 miles of wolf tracks in the snow.

A Coyote who sought to scavenge a Wolf kill, mauled by Wolf pack

Atwood and Gese located 92 wolf kills (presumably elk and deer), 77 (85 percent) of which were visited by coyotes. They witnessed 36 conflicts, involving 6 different coyote packs and the Bear Trap wolf pack, at wolf-kill sites. Although coyotes gained possession of the contested carcass on 17 occasions, all such carcasses were already nearly depleted. During the course of study, wolves killed one adult coyote and 2 pups, whereas 3 adult coyotes were killed by cougars; all such mortalities occurred within 200 meters of a wolf-killed deer or elk.

In most cases, wolves were able to drive coyotes away from deer or elk kill sites until they had their fill. Generally, coyotes gained access to wolf killed prey only when coyotes outnumbered wolves and only after wolves had already consumed most of their kill.

Interestingly, coyotes were able to spend more time at wolf-kill sites during the second winter of study, as compared to the first. As a result, formerly naive coyotes might have learned, through previous experience, to exploit carcasses in the latter stages of consumption when wolves were more inclined to back off.


A moment before the two Wolves take down a Coyote who sought 
to scavenge the Wolves kill

Atwood and Gese concluded the following: "Coyotes do not perceive wolves as a threat requiring generalized spatial avoidance. Rather, the threat of aggressive interactions with wolves is spatially discrete and primarily contained to areas adjacent to carrion resources."

Although the researchers don't dwell on the point, these findings imply that coyotes in northern Montana are learning to cope with wolves, and may even benefit from the larger canid's presence.

Conclusions

The gray wolf is definitely coming back to re-claim historic range it lost to coyotes decades ago. What will happen to coyotes in the meantime is anyone's guess. Some predict the demise of coyotes, whereas others believe coyotes will adjust, and maybe even prosper, in the presence of a more dominant canid.

The outcome will vary from one area to the next, depending upon a host of environmental circumstances.

Ironically, at least across the whitetail's northern range, both predators will benefit from man's mismanagement of deer wintering habitat. Resultant poor quality winter habitat, when coupled with the presence of two capable deer predators, will undoubtedly lead to excessive deer mortality during and following severe winters -- and ultimately contribute to declining deer numbers.

Just remember, coyotes are survivors. They are the clever predator that humans couldn't eradicate with all their traps, poisons, and guns. I don't expect wolves to be any more successful. In fact, here in Michigan's UP, deer hunter sighting rates of coyotes have doubled, while that of wolves have tripled, in the past 10 years.

"In the face of danger, some animals will enter a tonic state(Thanatosis) as a last-ditch shot at survival".............. "In fact, playing dead" can be a life-saving behavior"............."Opossums sell their performance by releasing a foul odor during thanatosis that suggests they've been rotting for days".............."The eastern hog-nose snake uses a similar, smelly defense mechanism while laying motionless, and has also been known to spit up blood"............."Playing dead can also be used as a mating strategy"............."The nursery web male spider offers a silk-wrapped insect to a female"............"The male plays dead and allows himself to be dragged along with the package"............"He revives himself when the female starts to feed-----An ingenius way to make your own bed, getting to sleep in it!"

https://www.thoughtco.com/why-some-animals-play-dead-373909

Why Some Animals Play Dead

2/2/18; Regina Bailey

A number of animals including mammals, insects, and reptiles exhibit a type of adaptive behavior known as playing dead or tonic immobility. This behavior is commonly seen in animals that are lower on the food chain but can be exhibited in higher species. When faced with a threatening situation, an animal may appear lifeless and may even emit odors that resemble the smell of decaying flesh. Also known as thanatosis, playing dead is often used as a defense mechanism, a trick to catch prey, or a means to sexually reproduce.

Snakes sometimes pretend to be dead when they sense danger. The eastern hognose snake resorts to playing dead when other defensive displays, such as hissing and puffing up the skin around their head and neck doesn't work. These snakes turn belly up with their mouths open and their tongues hanging out. They also emit a foul-smelling liquid from their glands that deters predators.

Eastern Hognose Snake Playing Dead. Ed Reschke/Getty Images

Certain animals play dead as a defense against predators. Entering into a motionless, catatonic state often dissuades predators as their instinct to kill drives their feeding behavior. Since most predators avoid dead or rotting animals, displaying thanatosis in addition to producing foul odors is enough to keep predators at bay.

Playing Possum

The animal most commonly associated with playing dead is the opossum. In fact, the act of playing dead is sometimes referred to as "playing possum". When under a threat, opossums can go into shock. Their heart rate and breathing is reduced as they fall unconscious and become stiff. By all appearances they seem dead. Opossums even excrete a liquid from their anal gland that mimics odors associated with death. Opossums can remain in this state for as long as four hours.

Virginia Opossum Plays Dead. Joe McDonald/Corbis Documentary/Getty Images

Fowl Play

A number of different bird species play dead when under threat. They wait until the threatening animal has lost interest or is not paying attention and then they spring to life and make their escape. This behavior has been observed in quail, blue jays, different species of ducks, and hens.

Ants, Beetles and Spiders

When under attack, young fire ant workers of the species Solenopsis invicta play dead. These ants are defenseless, unable to fight or flee. Ants that are just a few days-old play dead, while ants that are a few weeks-old flee, and those that are a few months-old stay and fight.

Some beetles pretend to be dead when they encounter predators such as jumping spiders. The longer the beetles are able to feign death, the greater their chances for survival.

Some spiders pretend to be dead when facing a predator. House spiders, harvestmen (daddy longlegs) spiders, huntsman spider, and black widow spiders are known to play dead when they feel threatened.

Sexual cannibalism is common in the insect world. This is a phenomenon in which one partner, typically the female, eats the other before or after mating. Praying mantis males for example, become motionless after mating to avoid being eaten by their female partner.

Sexual cannibalism among spiders is also common. Male nursery web spiders present an insect to their potential mate in the hopes that she will be amenable to mating. If the female starts to feed, the male will resume the mating process. If she does not, the male will pretend to drop dead. Should the female start to feed on the insect, the male will revive himself and continue to mate with the female.

This behavior is also seen in the Pisaura mirabilis spider. The male offers the female a gift during a courtship display and copulates with the female while she is eating. Should she turn her attention to the male during the process, the male feigns death. This adaptive behavior increases the males chances of copulating with the female.

Animals also use thanatosis in order to trick prey. Livingstoni cichlid fish are also called "sleeper fish" for their predatory behavior of pretending to be dead in order to catch prey. These fish will lie down at the bottom of their habitat and wait for a smaller fish to approach. When in range, the "sleeper fish" attacks and consumes the unsuspecting prey.

Some species of pselaphid beetles (Claviger testaceus) also use thanatosis to get a meal. These beetles pretend to be dead and are carried away by ants to their ant nest. Once inside, the beetle springs to life and feeds on the ant larvae.