Wolves, cougars, elk in Yellowstone, USA


This video says about itself:

Fearless predator – Cougar attack bears, deer and jaguar

Puma (mountain lion, cougar) is a predator of the Puma [genus] of the cat family. It lives in North and South America.

From the S.J. & Jessie E. Quinney College of Natural Resources, Utah State University in the USA:

Fearing cougars more than wolves, Yellowstone elk manage threats from both predators

August 2, 2019

Wolves are charismatic, conspicuous, and easy to single out as the top predator affecting populations of elk, deer, and other prey animals. However, a new study has found that the secretive cougar is actually the main predator influencing the movement of elk across the winter range of northern Yellowstone National Park.

The study highlights that where prey live with more than one predator species, attention to one predator that ignores the role of another may lead to misunderstandings about the impact of predators on prey populations and ecosystems. It also offers new insight into how prey can use differences in hunting behavior among predators to maintain safety from all predators simultaneously.

Utah State University researchers Michel Kohl and Dan MacNulty co-led the study, published in Ecology Letters, with Toni Ruth (Hornocker Wildlife Institute and Wildlife Conservation Society), Matt Metz (University of Montana), Dan Stahler, Doug Smith, and P.J. White (Yellowstone National Park). Their work was supported, in part, by the National Science Foundation, Ford Foundation, and Utah State University as part of Kohl’s doctoral research. The study was based on long-term data from the Park’s wolf and elk monitoring programs and Ruth’s cougar research, which is detailed in a forthcoming book from the University Press of Colorado.

The team revisited global positioning system (GPS) data from 27 radio-collared elk that had been collected in 2001-2004 when numbers of wolves and cougars were highest. Kohl and MacNulty combined the elk GPS data with information on the daily activity patterns of GPS-collared cougars and wolves and the locations of cougar- and wolf-killed elk to test if elk avoided these predators by selecting for ‘vacant hunting domains’, places and times where and when neither predator was likely to kill elk.

“Cougars hunted mainly in forested, rugged areas at night, whereas wolves hunted mainly in grassy, flat areas during morning and at dusk” said Kohl, lead author of the paper and now an assistant professor at the Warnell School of Forestry and Natural Resources at the University of Georgia in Athens. “Elk sidestepped both cougars and wolves by selecting for areas outside these high-risk domains, namely forested, rugged areas during daylight when cougars were resting, and grassy, flat areas at night when wolves were snoozing.”

Recognizing that cougars and wolves hunted in different places and at different times allowed the researchers to see how elk could simultaneously minimize threats from both predators. “Had we ignored the fact that these predators were on different schedules, we would have concluded, incorrectly, that avoiding one predator necessarily increased exposure to the other,” said MacNulty, who is an associate professor in USU’s Department of Wildland Resources and Ecology Center. “Movement out of the grassy, flat areas and into the forested, rugged areas to avoid wolves did not result in greater risk from cougars and vice versa because these predators were active at different times of the day.”

Despite the compatibility of elk spatial responses to cougars and wolves, Ruth, who is now executive director of the Salmon Valley Stewardship in Salmon, Idaho, cautioned that “some adult elk still end up on the cougar and wolf menu, with those in poor condition during winter being most at risk.”

Nevertheless, “the findings help explain why we observe wolves, cougars, and elk all coexisting and thriving on the Yellowstone landscape” said Stahler, who leads the current study of cougars in the Park. He notes that the ability of elk to coexist with wolves and cougars is consistent with their “long, shared evolutionary history”.

More surprising, however, was that cougars, not wolves, exerted the most pressure on elk habitat selection. “Wolves are often the presumed or blamed predator for any change in a prey population, numerical or behavioral,” said Smith, who leads the Park’s wolf program. “Our research shows that this is not necessarily true, and that other large predators in addition to wolves need to be considered.”

“Despite the fact that most prey species live in habitats with multiple predators, the majority of research on predator-prey interactions focuses on a single predator species,” added Betsy von Holle, program director for the National Science Foundation’s Division of Environmental Biology. “The novelty of this research is the simultaneous study of multiple predator species, revealing the complexity of predator avoidance behavior by the prey.”

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Lynx in Turkey, new study


This 2015 video is about a lynx in Turkey.

From Forschungsverbund Berlin in Germany:

Lynx in Turkey: Noninvasive sample collection provides insights into genetic diversity

June 17, 2019

Summary: A team of scientists collected data and samples (feces, hair) from the Caucasian Lynx (Lynx lynx dinniki), in a region of Anatolian Turkey over several years. The results of the genetic analyses indicated an unexpectedly high genetic diversity and lack of inbreeding despite the recent isolation of the study population.

Little is known about the biology and the genetic status of the Caucasian Lynx (Lynx lynx dinniki), a subspecies of the Eurasian lynx distributed across portions of Turkey, the Caucasus region and Iran. To collect baseline genetic, ecological, and behavioural data and assist future conservation efforts, a team of scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) collected data and samples in a region of Anatolian Turkey over several years. They were particularly interested in the question whether non-invasive samples (faeces, hair) were helpful to discern genetic diversity of the study population. The results of the genetic analyses indicated an unexpectedly high genetic diversity and lack of inbreeding despite the recent isolation of the study population, a result that would not have been obtained with the use of conventional samples. The data also revealed that females stay near home ranges in which they were born whereas males disperse after separation from their mothers. These insights into the genetics and behaviour of the Caucasian Lynx are published in the scientific journal PLOS ONE.

Among lynx species, the Eurasian Lynx has the widest geographical distribution. Previous research has largely focused on European populations, with the result that there is little known about the subspecies in Asia, such as the Caucasian and Himalayan subspecies. “Scientists still know surprisingly little about their ecological requirements, spatial structure and genetic diversity,” says Leibniz-IZW researcher Deniz Mengulluoglu (Department for Evolutionary Ecology). “Our study aimed at collecting baseline genetic, ecological and behavioural data of the lynx population in a mountainous region in north-west Anatolia.” Making use of box trapping and non-invasive faecal sampling allowed Mengulluoglu to extract DNA and conduct genetic analyses on a population scale. The lynx population had also been monitored via camera traps at 54 different stations for nearly a decade.

Looking into family relationships of individual lynx, the data revealed that females stay near the territories in which they were born whereas males disperse after separation from their mothers. Such behaviour is known from many mammals, most likely to avoid inbreeding. “We can conclude from our analyses that territoriality in lynx and philopatry in female lynx can result in low genetic diversity estimates if sampling is done in small study areas via box trapping alone,” says Mengulluoglu. This behaviour — females remaining in close proximity to their mothers’ territory — is called female philopatry, and Mengulluoglu and his team confirmed it for this subspecies. “Using faecal samples that were non-invasively collected, we were able to sample more non-territorial individuals, gaining information about an additional component of this lynx population.” Unless individuals become used to the presence of box traps within their own range (habituation), and thus are ready to enter them, sampling them by conventional means is unlikely. Hence habituation will bias conventional sample collection in favour of resident territorial individuals and their kittens.

A second important finding is that genetic diversity is unexpectedly high in this population. Lynx in north-west Anatolia are isolated from southern and north-eastern populations by a series of natural and human constructed barriers. “Population isolation can be harmful and, for example, lead to a loss of genetic variation. But it appears that genetic diversity is in fact substantial at the moment and matches the diversity found in European endogenous populations,” states senior author Daniel Foerster from the Leibniz-IZW, Department of Evolutionary Genetics. “Management should therefore focus on maintaining the current level of diversity.” As a first step, Mengulluoglu and Foerster recommend identification and conservation of primary lynx habitats and corridors in the region.

“We also need to address threats that can lead to future loss of genetic variation” adds Mengulluoglu. Since this study has set a baseline for comparison with future findings, similar work is needed for the other two Turkish populations in order to determine whether the three big populations are currently connected by gene flow at all, Mengulluoglu and Foerster say. Mengulluoglu is currently working on a long-term lynx monitoring project and the development of a “Turkish Lynx Conservation Action Plan” in collaboration with the Wildlife Department of Turkey.

Asiatic golden cats’ colours, new research


This 2017 video is called Rarest cats in the world: Asian Golden Cat.

From the Zoological Society of London in England:

The benefits of being different

Six different ‘color morphs’ of the Asiatic golden cat discovered in India’s Arunachal Pradesh

June 12, 2019

Six different colour morphs of the elusive Asiatic golden cat have been discovered in Northeast India — with the findings being hailed as “an evolutionary puzzle” — as the world’s greatest number of different coloured wild cat species in one area are reported.

The Indian scientists from international conservation charity ZSL (Zoological Society of London) and UCL discovered the colour morphs, during a wide-scale camera trapping study covering both community forests and protected areas across Dibang Valley, Northeast India.

The study, published on 7 June 2019 in the Ecological Society of America’s journal Ecology, aimed to uncover a greater understanding of human-wildlife interactions in the region but discovered a group of entirely different-looking animals on their camera traps — with an inkling they were all the exact same species.

The finding is said to spark more questions than it answers. However, understanding how this remarkable phenomenon takes hold in a population, may help scientists grasp how quickly species can adapt and evolve to changing environments. This would advise scientists of the resilience of the species to climate change or habitat degradation and destruction.

Colour morphs are not classed as different subspecies as they may live in the same area and even interbreed. However, if differences in their behaviour prevented them from interbreeding — this could represent the beginning of the evolutionary process into separate subspecies. A more well-known example of a colour morph is the melanistic (dark coloured) morph (aka black panther) of the common leopard (Panthera pardus).

Within the six colour morphs recorded, an entirely new colour morph was also found in one of the community-owned forests. The now named “tightly-rosetted” morph after the leopard-like rosettes tightly spaced on their gray coat, now sits alongside the already known: cinnamon, melanistic, gray, golden, and ocelot (due to its ocelot-like markings) types.

ZSL scientists believe that the wide variation displayed in the cat’s coats provides them with several ecological benefits. It enables them to occupy different habitats at different elevations — from wet tropical lowland forests to alpine scrubs — and provides camouflage while hunting different prey such as tropical pheasants or Himalayan pika (a small mountain-dwelling rabbit-like mammal).

Colour morphs are thought to arise from random genetic mutations and take hold in the population through natural selection. In this region, scientists suspect that the phenomenon is driven by competition with other big cats such as tigers (Panthera tigris) and clouded leopards (Neofelis nebulosa). Being melanistic in the misty mountains during nocturnal hunts, for example, may mean they are better concealed from their prey; making them more efficient predators.

Dr Sahil Nijhawan, the India-based lead author and British Academy Fellow at ZSL’s Institute of Zoology and UCL said: “According to evolutionary theory, if a colour morph is not beneficial for a species survival — over time, it should die out in the population. The fact that we have so many different colour morphs persisting in Dibang Valley shows there must be some ecological advantages to the variety of colours.

“We now know Dibang Valley hosts the world’s most diverse range of colour morphs of a wild cat species ever reported in one site, but we are only just starting to understand this rare ecological phenomenon. We need more studies that shed light on such unique adaptations and the benefits they provide to species, especially in a world where they must adapt quickly.”

Big cat evolution, videos


This 16 May 2019 video says about itself:

The Ghostly Origins of the Big Cats

All of today’s big cat species evolved less than 11 million years ago and yet their evolutionary history remains an almost total mystery.

But scientists have recently discovered a major clue about the origins of the big cats, one that could provide a whole new starting place for solving this puzzle. Thanks to Ceri Thomas for the excellent Panthera blytheae and Panthera atrox!

Bringing lynxes back to Scotland, new study


This 2017 video from Britain says about itself:

Rewilding the UK with Lynx

BBC’s Mike Dilger discusses the benefits of Lynx reintroduction.

From the University of Stirling in Scotland:

Proposed reintroduction of the Eurasian lynx to Scotland

March 29, 2019

Experts have used an innovative approach to model the proposed reintroduction of the Eurasian lynx to Scotland.

Researchers used state-of-the-art tools to help identify the most suitable location for lynx reintroduction in Scotland — and how this choice might affect the size of a population and its expansion over subsequent decades. Significantly, they believe their model will inform and enhance decision-making around large carnivore reintroductions worldwide.

The study was led by University of Stirling PhD researcher Tom Ovenden as part of his Masters in Environmental Forestry at Bangor University, with support from the University of Aberdeen.

Mr Ovenden said: “Reintroducing large carnivores is often complicated and expensive, meaning that getting things right first time is extremely important. Therefore, advances in modelling approaches, as utilised during our study, are extremely valuable.

“Our research considered several proposed reintroduction sites, showing how these models can be used as a safe and relatively inexpensive way of assessing the suitability of reintroduction proposals and providing the evidence required to inform decision-making at an early stage.

“Recent advances in both ecological theory and modelling approaches have made the incorporation of individual species’ complex behaviours in novel environments more realistic. We applied this approach to the potential reintroduction of Eurasian lynx in Scotland — and demonstrated the power of this new, sophisticated model. Our research demonstrates the potential of this approach to be applied elsewhere to help improve reintroduction success in large carnivores, from the safety of a modelling environment.”

The lynx is thought to have become extinct in the UK during the medieval period, around 1,300 years ago. In recent years, its potential reintroduction has been widely debated.

Using current land cover data, Mr Ovenden conducted an initial desk-based study to establish the current location and extent of suitable forest habitat for lynx in Scotland, updating historic work. Further research to identify the demographic and dispersal characteristics of the lynx elsewhere in Europe, provided the model with the necessary parameters.

The team used this information to investigate the suitability of three proposed release sites: the Scottish component of Kielder Forest, in the Borders; Aberdeenshire; and the Kintyre Peninsula. They used the model to assess how the lynx would establish a population, spread and colonise new habitat from each potential reintroduction site over a period of 100 years.

The results showed that Scotland possesses sufficient, connected habitat to offer a realistic chance of population establishment and that some sites are more suitable than others.

Of the three sites considered, the study indicated that the Kintyre Peninsula was the most suitable, with the population spreading across the Highlands in the 100 years following release. Significantly, the Central Belt would act as a barrier to colonisation between the Highlands and Southern Uplands providing evidence for two distinct habitat networks.

“This initial research is encouraging and suggests that Scotland is indeed ecologically suitable for the reintroduction of Eurasian lynx — but this suitability is highly dependent on where reintroduction takes place and more modelling work is required,” Mr Ovenden said. “Our research informs one aspect of a complex decision-making process that must involve a wide range of stakeholders and, as a result, it does not recommend whether we should, or should not, reintroduce Eurasian lynx to Scotland.

“We have established a solid foundation upon which more modelling can now be conducted, however, further research is required to assess other important issues — such as socio-economic factors and public attitudes — to enable informed, comprehensive decision-making. It is our hope that this tool will not only provide evidence to guide the current debate in Scotland, but can be used more widely in discussions around large carnivore reintroductions globally.”

Jo Pike, Director of Public Affairs at the Scottish Wildlife Trust, said: “Returning the lynx to our landscape as a top predator could help restore the health of Scotland’s natural ecosystems. Any future reintroduction would have to be carefully planned, widely consulted on, and rigorously assessed against national and international guidelines. This research is a useful contribution to the evidence base that needs to be developed over the coming years.”

Notably, Mr Ovenden wrote his entire dissertation using solar power, while running the Handa Island nature reserve, in the Inner Hebrides, for the Scottish Wildlife Trust. He worked under the supervision of Professor John Healey, of Bangor University, and collaborated with Dr Steve Palmer and Professor Justin Travis, of the University of Aberdeen.

Mr Ovenden is now working towards a PhD at Stirling, in collaboration with Forest Research and The Scottish Forestry Trust, on the resilience of UK forests to extreme climatic events.

The study, Improving reintroduction success in large carnivores through individual-based modelling: how to reintroduce Eurasian lynx (Lynx lynx) to Scotland, is published in Biological Conservation.

Saber-toothed cats, other La Brea, USA fossils


Cats, from left to right: Dantheman9758/Wikimedia Commons (CC BY 3.0); Charles R. Knight; Charles R. Knight; C. Chang; Dantheman9758/Wikimedia Commons (CC BY 3.0); DiBgd/Wikimedia Commons (CC BY-SA 4.0); Iconographia Zoologica; Jean Charles Werner; Reichenbach, Der Naturfreund, 11-12; Jean Charles Werner; Richard Lydekker; C. Chang. Source: A.D. Rincón et al/J. of Vertebrate Paleo. 2011

By John Pickrell in the USA, 6:00am, March 24, 2019:

Saber-toothed cats were fierce and family-oriented

A freshly detailed picture shows Smilodon helping the injured and the young

The adolescent saber-toothed cat on a summertime hunt realized too late that she had made a terrible miscalculation.

Already the size of a modern-day tiger, with huge canine teeth, she had crept across grassy terrain to ambush a giant ground sloth bellowing in distress. Ready to pounce, the cat’s front paw sank into sticky ground. Pressing down with her other three paws to free herself, then struggling in what has been called “tar pit aerobics”, she became irrevocably mired alongside her prey.

Scenarios much like this played out repeatedly over at least the last 35,000 years at California’s Rancho La Brea tar pits. Entrapped herbivores, such as the sloth, attracted scavengers and predators — including dire wolves, vultures and saber-toothed Smilodon cats — to what looked like an easy meal. Eventually the animals would disappear into the muck, until paleontologists plucked their fossils from the ground in huge numbers over the last century.

THE BADDEST CAT On countless occasions over thousands of years, predator and prey alike — such as saber-toothed cats and giant ground sloths — became mired in the tar at what is now Rancho La Brea in southern California, leaving loads of fossils for researchers to study. Picture by Sergio de la Rosa

Five million or so fossils have been found at the site. But “it’s not like there was this orgy of death going on”, says Christopher Shaw, a paleontologist and former collections manager at the La Brea Tar Pits and Museum in Los Angeles. He calculates that such an entrapment scenario, dooming 10 or so large mammals and birds, would have needed to occur only once per decade over 35,000 years to account for that bounty of fossils.

At La Brea, the collection of Smilodon fatalis fossils alone includes more than 166,000 bones, from an estimated 3,000 of the ill-fated prehistoric cats. Famed for their fearsome canines, which grew up to 18 centimeters long, S. fatalis weighed as much as 280 kilograms, bigger than most of today’s largest lions and tigers.

Fossils of S. fatalis, the second largest of three Smilodon species that roamed the Americas during the Pleistocene Epoch, have been found across the United States and in South America, west of the Andes as far south as Chile. And a recent study put S. fatalis in Alberta, Canada, about 1,000 kilometers north of its previously known range.

But the La Brea fossil site, unique in offering up so many specimens, is the source of the vast majority of knowledge about the species. There, fossils of dire wolves and saber-toothed cats together outnumber herbivores about 9-to-1, leading scientists to speculate that both predators may have formed prides or packs, similar to modern lions and wolves. Yet a small number of experts argue against cooperative behavior for Smilodon, reasoning that pack-living animals would have been too intelligent to get mired en masse.

New studies may help settle the debate about Smilodon’s sociality, and answer questions about how the cat lived and why it died out 10,000 to 12,000 years ago.

“We have an innate curiosity to understand what it was doing and why it went extinct”, says Larisa DeSantis, a vertebrate paleontologist at Vanderbilt University in Nashville. Now, she says, “we can answer these questions.”

DeSantis is studying microscopic wear on fossil teeth and chemical signatures in the enamel to reveal Smilodon’s diet. Other scientists are doing biomechanical studies of the skull, fangs and limbs to understand how the powerful cat captured and killed its prey. Some researchers are extracting DNA from fossils, while others are gathering data on the paleoclimate to try to piece together why Smilodon died out.

“It’s the T. rex of mammals … a big, scary predator”, says Ashley Reynolds, a paleontology Ph.D. student and fossil cat researcher at the University of Toronto. She presented the Alberta fossil find in October in Albuquerque at the Society of Vertebrate Paleontology conference. Explaining why Smilodon cats continue to excite researchers, she says, “They’re probably the baddest of all the cats that have ever existed.”

Safety in numbers

Whether Smilodon was a pack hunter has long been debated (SN: 10/28/17, p. 5) because living in groups is rare among large cats today. But an unusual number of healed injuries in the Smilodon bones at La Brea makes it unlikely that these cats were solitary, DeSantis and Shaw reported in November in Indianapolis at a meeting of the Geological Society of America.

More than 5,000 of the Smilodon bones at La Brea have marks of injury or illness: tooth decay, heavily worn arthritic joints, broken legs and dislocated elbows that would have occurred before the animals’ tar burial. Dramatic examples include crushed chests and spinal injuries, which the cats somehow survived. “You would actually wince to see these horribly, traumatically injured specimens”, says Shaw, who is also coeditor of the 2018 book Smilodon: The Iconic Sabertooth.

One particularly debilitating injury was a crippled pelvis, but evidence of new bone growth shows that the animal lived long enough for healing to occur. “There was a lot of infection, pain and smelly stuff, and just a really awful situation for this animal, but it survived well over a year”, Shaw says. “To me that indicates [the injured cat] was part of a group that helped it survive by letting it feed at kills and protecting it.”

Shaw and DeSantis looked at a series of specimens with what were probably agonizing maladies in the teeth and jaws, including fractured canines and massive infections that left animals with misshapen skulls.

“These animals probably couldn’t have gone out … to kill anything”, Shaw says. “You know how it is when you have a toothache. This is like that times 100.”

DeSantis compared microscopic pits and scratches on the surface of the teeth of injured animals with microwear on the teeth of seemingly healthy Smilodon cats. The injured cats’ dental surfaces indicated that the animals were eating softer foods, which would have been less painful to chew, “likely a higher proportion of flesh, fat and organs, as opposed to bone”, she says.

The findings are consistent with the interpretation that Smilodon was a group-living animal, she says, and that the cats “allowed each other access to food when [injured pack members] couldn’t necessarily take down their own prey.”

Reynolds agrees that the healed injuries are persuasive evidence that Smilodon lived in groups. “When you see an animal with really nasty injuries that healed somehow, it does make you wonder if they were cared for.”

Not everyone is convinced, however. Ecologist Christian Kiffner of the Center for Wildlife Management Studies in Karatu, Tanzania, has studied modern carnivores such as African lions and spotted hyenas. “Relatively long survival of Smilodon fatalis individuals after dental injuries had occurred does not necessarily provide airtight evidence for a specific social system in this species”, he says. “It is very, very difficult to use patterns in Pleistocene carnivore [fossil] assemblages to make inferences about behavior of an extinct species.”

Even if the saber-toothed cats did live in groups, the animals’ exact social structure remains an open question, Reynolds says. Modern lion prides have numerous females and several younger males led by an alpha male, with intense competition between male lions. As a result, males are much bigger than females, as the males must work hard to defend their positions.

Despite searching, scientists have not found obvious evidence of a size difference between the sexes in Smilodon; researchers can’t even tell which La Brea fossils are male or female. Size differences between the sexes, if they existed, may have been small.

“That lack of sexual dimorphism is odd”, says Blaire Van Valkenburgh, a UCLA paleontologist who studies fossil carnivores. Sex-related size differences are seen in many big cats today, most particularly lions. She thinks the lack of sexual dimorphism in Smilodon might hint at a different social structure. Perhaps males weren’t competing quite so intensely for access to females. Maybe there was no single alpha male preventing the majority of males from making a move.

Family affair

Perhaps Smilodon groups had an alpha female rather than an alpha male, or an alpha pair. Such is the case in modern wolves and coyotes, which have less pronounced size differences between sexes than lions do. The prehistoric cats “could have had extended family structures [similar to wolves] where uncles and aunts hung around, because it probably took a while to raise the young saber-toothed cats”, Van Valkenburgh suspects.

Kittens may have taken a long time, as long as 22 months, to get most of their adult teeth, she says. The upper canines took even longer, as much as three years or more, to reach their massive size, researchers reported in PLOS ONE in 2015. Modern lions, in contrast, typically have all of their adult teeth by 17 months, Van Valkenburgh says.

Smilodon kittens also probably went through a substantial learning curve before attempting to take down large prey. “It took longer for them to learn how to safely kill something without breaking their teeth or biting in the wrong place and hurting themselves”, Van Valkenburgh speculates.

Pack living would enable this slower development: “If you’re a social species, you can afford to grow at a slower rate than a nonsocial species because you have a family safety net,” Reynolds says. She is studying Smilodon fossils from Peru’s Talara tar pits for evidence of slow bone development using bone histology, examining thin cross sections under a microscope to determine such things as age and growth rate.

To understand how saber-toothed cats eventually took down prey, Van Valkenburgh joined paleobiologist Borja Figueirido of the University of Málaga in Spain and others. The group studied the biomechanics of Smilodon’s killing bite and how the animal used its sabers. That work, published in the October 22, 2018 Current Biology, adds to a consensus that the cat used its powerful forelimbs, which existed even in the youngsters (SN Online: 9/27/17), to pin prey before applying a lethal bite to the neck.

“The specialization of being a saber-toothed appears to have been partly to effectively take prey larger than yourself and to do that very quickly,” Van Valkenburgh says. With the prey tightly gripped, a Smilodon cat would position itself so that one or two really strong canine bites would rip open the pinned animal’s throat.

In contrast, lions suffocate prey — one lion may clamp its jaws around the neck, crushing the windpipe, while another uses its mouth to cover the victim’s nose and mouth. Using this slower method would have increased Smilodon’s chances of injuring or damaging those precious canine teeth.

Diverging senses

Smilodon and its extinct saber-toothed relatives are on a branch of the cat family tree that is far from today’s cats. Scientists think Smilodon’s branch diverged from the ancestors of all living cats about 20 million years ago. Given the evolutionary distance, researchers are still trying to determine how similar — or different — Smilodon was from its living feline cousins. A recent focus has been the cat’s sounds and senses.

At the October vertebrate paleontology conference, Shaw presented evidence that Smilodon may have roared, as do lions, tigers, leopards and their close relatives. The clues come from 150 La Brea fossils that were once part of the hyoid arch, or larynx, in the Smilodon throat. (Tar pits stand out for preserving tiny bones rarely found elsewhere.) The small fossils are very similar in shape and style to those of roaring cats. House cats and others that purr have a different arrangement of bones.

Smilodon may have “used this type of communication as an integral part of social behavior”, Shaw says. Roaring, however, is not a sure sign of pack living, Reynolds notes; most roaring cats today do not live in large groups.

How Smilodon’s sense of smell compared with living cats’ is something else researchers wonder about. To probe this part of the extinct animal’s biology, a team lead by Van Valkenburgh looked at Smilodon’s cribriform plate — a small, perforated bone inside the skull. Smell-sensing nerve cells pass through holes in the plate from the olfactory receptors in the nose to the brain. The size and number of holes are thought to correlate with the number of receptors and, therefore, the extent of an animal’s sense of smell.

To confirm this link, Van Valkenburgh’s team combined CT scans and 3-D images of skulls from 27 species of living mammals with information on the number of olfactory receptor genes. A CT scan of a skull revealed that Smilodon may have had slightly fewer olfactory receptor nerve cells than a domestic cat, the researchers reported at the paleontology conference. Smilodon’s sense of smell was perhaps 10 to 20 percent less keen than a modern lion’s, says Van Valkenburgh, whose team reported the findings in the March 14, 2018 Proceedings of the Royal Society B.

Smilodon “might have relied more heavily on their eyes and their ears”, she says. Perhaps, in an ancient evolutionary divergence, Smilodon’s level of reliance on smell went in a slightly different direction than in modern big cats.

Saber-toothed swan song

As the pieces of the Smilodon puzzle fall into place, perhaps the biggest remaining mystery is why the animal disappeared 10,000 to 12,000 years ago. Debate about the extinction of some of North America’s large mammal species swings between blaming humans and climate change (SN: 11/10/18, p. 28). While humans, who probably arrived on the continent more than 15,000 years ago, and Smilodon certainly knew one another in the Americas, they may not have overlapped at La Brea, Shaw says. The earliest evidence of people in the Los Angeles Basin is about 11,000 years ago, by which time Smilodon may or may not already have gone. Nevertheless, human hunting of large prey elsewhere in the Americas could have led to a scarcity of food for the big cats, he says.

One theory holds that Smilodon went through tough times at La Brea when lack of prey forced the saber-toothed cats to consume entire carcasses including bones. This has been posited as the reason for all those broken teeth among the La Brea fossils. But DeSantis isn’t convinced; she thinks breakages happened during scuffles with prey. She says dental microwear suggests that Smilodon was not eating great quantities of bone.

Some opportunistic carnivores, such as cougars, did eat bone and managed to survive to the modern day. Perhaps Smilodon couldn’t adapt to hunting smaller prey when larger herbivores disappeared, also around 10,000 to 12,000 years ago (SN: 11/24/18, p. 22).

“A lot of the large prey on the landscape go extinct,” DeSantis says. “You lose out on the horses, camels, giant ground sloths, mammoths and mastodon. That’s got to have had an impact.”

The challenge of dating fossils from the tar pits has been one hurdle to understanding exactly what was going on with Smilodon over time. Bones deposited over many thousands of years get jumbled by movement in the tar, for reasons experts don’t fully understand. Plus, the tar itself becomes embedded in each specimen, complicating carbon dating.

However, new methods of chemically pretreating fossils to remove the tar have made carbon dating much easier and cheaper — and a multi-institutional project is now dating hundreds of Smilodon and other bones. Researchers will soon be able to track changes in Smilodon over the 35,000 years of prehistory recorded at La Brea and correlate fossil changes to known changes in climate over that time.

“We’re going to have a much better handle”, Van Valkenburgh says, “on what was going on towards the end of their existence.”

North American bobcats and lynx, wildlife identification


This 2010 video from Texas in the USA says about itself:

Shot over a 2 year period, this video chronicles the 6 episodes of 2 different bobcats that visited our yard on a creek in far North Dallas; one probably raised in captivity and the other very wild indeed.

From the University of British Columbia Okanagan campus in Canada:

Copy cats: When is a bobcat not a bobcat?

Telling similar animals apart challenges even the experts

January 23, 2019

Two UBC Okanagan biologists, who have publicly solicited images of wild cats for their research, have answered that question.

Their recently published study explains how hard it can be when it comes to wildlife classification — even experts have difficulty agreeing on whether a cat in a picture is a bobcat or a lynx.

Biology Professor Karen Hodges and master’s student TJ Gooliaff collected and compared wildlife images for several years as part of their research tracking bobcat and lynx distributions in British Columbia. Camera trapping and solicitation of wildlife pictures through citizen science have become common tools in ecological research, explains Gooliaff.

While it’s generally easy to collect many images of animals, some species are difficult to tell apart, making species classification challenging.

Camera-trapping and citizen-science studies collect many wildlife images for which correct species classification is crucial,” says Gooliaff. “Even low misclassification rates can result in erroneous estimation of the geographic range or habitat use of a species — including underestimation of the occupancy, habitat preferences or distribution of a species. This potentially hinders conservation and management efforts.”

There are some species, such as mountain goats and porcupines, where it’s obvious. But for others, including bears, deer, lemurs, wild cats and antelopes, classification to a species may be unreliable as the animals can be similar in size, shape or colour. It gets even trickier when the pictures are blurry, taken in poor lighting, show only part of the animal or when only one image is available for a given animal.

In a 2018 study published in the Journal of Wildlife Management, Gooliaff and Hodges solicited 4,399 images of bobcats and lynx from the public across British Columbia to examine the provincial distribution of each species. They used pictures, trapping records and other data sources to develop current range maps.

Because lynx and bobcats are similar, Gooliaff and Hodges then measured agreement among experts who were asked to distinguish between bobcats and lynx from those images. The researchers asked 27 individual bobcat and lynx authorities to classify the species in a subsample of 300 images to see how often the experts agreed on whether it was a bobcat or a lynx.

What became clear was that the experts found it difficult to tell bobcats and lynx apart — indeed, many images were labelled as “unknown” by the experts — and they did not always agree with each other. Experts were inconsistent even with themselves, changing their classifications of some images when they were asked to reclassify the same pictures months later.

Gooliaff and Hodges also examined if agreement among experts varied with what part of the animal was in each image (paws, head, tail, etc.), the habitat in the background, and whether it was day or night. These factors all affected how many experts agreed on the species in each image.

“These results are particularly troubling given that the images were all of high photographic quality,” says Gooliaff.

Hodges says this study helps researchers improve how they work with images, by knowing when misidentifications are most likely. Further, classification of images of similar?looking species should not be relied upon for critical conservation or management decisions. Instead, physical or genetic evidence should be required in these cases.

She also emphasises that pictures provided by the public are becoming a powerful tool in wildlife research and eventual conservation and management efforts. This research benefits citizen science and image-based studies, as they continue to refine how people use submitted images.

“We encourage researchers who use images to be more willing to call the species in a picture “unknown” or to use them as a screen for habitats or regions where more survey work should be done, rather than trusting images alone.”

The image study, partially funded by a Natural Sciences and Engineering Research Council grant, was recently published in Ecology and Evolution.