Tag Archives: carnivores

How bringing cougars to cities could actually save lives

Allowing cougars to re-populate back to their historic range could save hundreds of human lives and prevent tens of thousand of injuries, a new study reports. Counter-intuitive as this may seem, the numbers actually add up — while we may expect some property damage from the predators, they’d actually help us out in the end by keeping the US’s deer population in check.

Deer are most active between 6 and 9 p.m. and generally travel in herds – if you see one, there is a strong possibility others are nearby.
Image credits State Farm/Flickr

If I asked you to pick the animals with the highest human death toll between deers and cougars, which would you pick? The cougars, undoubtedly. And you’d be wrong. Sure, a cougar is fiercer than a deer, it has both teeth and claws and isn’t shy about using them while a deer is uh…a nuisance? But by sheer weight of numbers (and an inability to act when confronted with headlights) white-tailed deer in the US cause more than a million car collisions, resulting in more than 200 deaths, every year.

By the early 1900s, we pushed cougars away from our cities because they were dangerous, but a new study suggests this exact trait is why we should bring them back. Laura R. Prugh, a wildlife scientist at the University of Washington, Sophie L. Gilbert, a wildlife ecologist at the University of Idaho and several colleagues argue that allowing eastern cougars to return to their historic range could prevent 155 human deaths, 21,400 human injuries, and save $2.3 billion over the course of 30 years.

The team bases their estimations on studies they performed in 19 states including South Carolina, Maine, Wisconsin, Ohio, and Missouri. Delaware, Rhode Island, Maryland and Illinois were historically part of the eastern cougar’s territory, however, they lack the required open forestland to support a viable cougar population today, the team reported. They also said that if left to their own devices, it’s entirely possible that the cougars will re-populate these areas on their own: over the past few decades, they’re been sighted in parts of the Midwest and more recently in the East. Dr. Prugh advocates for this kind of natural repopulation, which would face less resistance than a human-engineered one, she believes.

Pictured: statistically less dangerous to you than a deer.
Image credits Wikimedia user Dcoetzee

They looked at the number of individuals to see how deer populations grow in each area, how many car crashes involve deer and how they increase as the deer population grows. They looked at cougars’ hunting behavior, and settled for an average of 259 deer kills per individual per average lifespan of 6 years, and an 850 square miles area of forested land needed to sustain a wild population of the felines.

They then tested several mathematical models to calculate the cougars’ effect on the deer population. The first question they needed to consider was if cougars would prey on the deer that are too starved, old, or sick to survive and don’t actually cause accidents. Dr. Prugh calculated for a “conservative” 75% of deer kills as animals that would’ve died anyway.  They also considered that as adult deer decrease in number, more fawns survive — so killing deer doesn’t immediately shrink the population.

But it’s not all roses. The catch is that we’re dealing with dangerous, deadly predators here, which are perfectly capable of killing humans. Their population would stabilize at considerable numbers in some states — about 1000 in New York and Wisconsin each, around 350 in Missouri and between 8-15 in New Jersey, the team estimates. They also expect to see livestock loss of around US$2.35 million per year in the areas, and some pet loss, though the team wasn’t able to estimate this — since there is little data on what happens to pets after they are lost.

The scientists also estimated that we could expect less than one victim per year, for a total of under 30 lives lost, far less than the number of lives saved. But they admit that the emotional response to predators is one element they can’t factor in — no matter how many people are saved in the end, death by deer is very different to death by cougar.

“The idea of being killed in a car crash with a deer just doesn’t scare people the way the idea of a cougar leaping on your back in the woods does,” Dr. Prugh said.

But she hopes that if cougars do return to the Eastern states, an understanding that they could bring tangible benefits will make people “a little more accepting, even if they are still scared.”

The full paper titled ” Socioeconomic benefits of large carnivore recolonization through reduced wildlife-vehicle collisions” has been published online in the journal Conservation Letters.

New fossil sheds light on the ancestor of dogs, bears and tigers

Cats, dogs, as well as many well known and loved wild animals such as seals, lions, tigers and bears trace their ancestry to primitive carnivorous mammals dating back to 55 million years ago, at the beginning of a time period called the Eocene. A study, published in the most recent issue of the Journal of Vertebrate Paleontology, discusses the origins of this group (called the ‘carnivoraformes’), and describes one of the earliest specimens to belong to it – in other words, one of the earliest primitive animals to belong to the group.

The species in case is called Dormaalocyon latouri, and new fossils of it have been found in Belgium. The new specimens were found by lead author Floréal Solé and his colleagues and they make for a better identification and interpretation of the features and the role that this animal plays.

“Its description allows better understanding of the origination, variability and ecology of the earliest carnivoraforms,” says Solé.

All in all, they found over 250 teeth and ankle bones. The teeth clearly show that Dormaalocyon is close to the origin of carnivoraforms and that it is one of the most primitive members of the group, while the ankles suggest that it was arboreal, living and moving through the trees. There has been some discussion whether or not the species did live or not in the trees (based on previously found fossils), but with new evidence in sight, it seems clear that we are in fact dealing with an arboreal mammal. Dr. Solé also believes that they originated in Europe, and it was at about this time (55 million years ago) that they started to make their way towards North America.

Personally, I find this intriguing. Mind you, the face of the Earth looked much different than it does today, and Europe was much closer to North America, but the distance is still pretty much for an animal. Europe and North America started splitting up in the Jurassic, some 140 million years ago. I may be missing some information, but at least from this point of view, it seems likelier that the emergence of Dormaalocyon in North America took place somewhat earlier than the Eocene, when Europe and North America were closer.

A reconstruction of the continents, as they looked in the Eocene.

Either way, the fossils suggest there were even more primitive species in the group in an earlier time period, the Paleocene.

“The understanding of the origination of the carnivoraforms is important for reconstructing the adaptation of placental mammals to carnivorous diet. Therefore, Dormaalocyon provides information concerning the evolution of placental mammals after the disappearance of the largest dinosaurs (at the Cretaceous-Paleogene extinction event). Our study shows that the carnivoraforms were very diversified at the earliest Eocene, which allows hypothesizing that they were probably already diversified during the latest Paleocene.”

This means that there are even more fossils out there just waiting to be found and provide more information on the ancestry of this magnificent group.

Journal Reference:

  1. Solé, F., R. Smith, T. Coillot, E. De Bast, T. Smith. Dental and Tarsal Anatomy of ‘miacis’ Latouri and a Phylogenetic Analysis of the Earliest Carnivoraforms (mammalia, Carnivoramorpha). Journal of Vertebrate Paleontology, 34(1): 1-21; 2014 [link]
The 200-kilogram 'bear otter' is one of several large carnivores that became extinct around 2 million years ago. ILLUSTRATION BY VICTOR LESHYK

Early humans responsible for ancient carnivore wipe-out in Africa, not climate change

sabre_tooth_cat

Millions of years ago, the wild savannas of Africa were teeming with carnivore wildlife, much more diverse than what we see today: lions, hyenas and other large-bodied carnivores. Paleontologist Lars Werdelin at the Swedish Museum of Natural History in Stockholm suggests the carnivore species decimation that began roughly two million years ago can be attributed to the intervention of early human ancestors that began eating meat at the time, consuming both prey and predator.

Over the past few thousands of years human intervention has led to the extinction of a number of species,  ranging from moas—giant, flightless birds that lived in New Zealand—to most lemurs in Madagascar. Plants and water creatures weren’t spared either.Where and when humans or their ancestors began to make dramatic changes to the ecosystem is a matter of debate that has remained largely unresolved.

The 200-kilogram 'bear otter' is one of several large carnivores that became extinct around 2 million years ago. ILLUSTRATION BY VICTOR LESHYK

The 200-kilogram ‘bear otter’ is one of several large carnivores that became extinct around 2 million years ago. ILLUSTRATION BY VICTOR LESHYK

Fossil records collected  from eastern and southern Africa, like Lothagam on the western shore of Lake Turkana in northern Kenya , reveal that some seven million years ago the plains of Africa were dominated by varied group of carnivores: sabertooth cats, strange long-legged hyenas, giant bear dogs (members of an extinct family of carnivores called Amphicyonidae), a leopard-size member of the mustelid family to which badgers belong, as well as small  carnivores related to today’s civets and mongooses also prowled there. Four million years ago, other carnivores began to surface: hyena species ancestral to the brown hyena found in southern Africa today,  modern-looking big cats, early spotted hyenas, several dog species, giant otters that have no modern counterpart, a giant civet and a variety of smaller carnivores.

After peaking around 3.5 million years ago, the number of large carnivore species declined gradually over the next million and a half years or so, mostly because the rate at which new species originated slowed down while the extinction rate held steady. Still, carnivores reigned supreme, and our flimsy ancestors,   such as Australopithecus afarensis, whose brain and body were only a bit bigger than a chimp’s,  where really no match to the great families of ancient carnivores.

A hungry hominin

Illustration of Homo Erectus.

Illustration of Homo Erectus.

Starting with  Homo erectus, the first hominin that actually resembles modern humans, things began to change. Homo erectus ate meat, congregated with peers and used tools, like sharp stones. Oddly or not, some 1.5 million years ago, corresponding to the presence of Homo erectus, carnivore species began to massively die out. Some scientists believe climate change was responsible, others like Werdelin believe early humans had the biggest part to play in this massacre. There are however somethings that don’t add up, despite the timing.

” If competition with H. erectus was to blame, then the steep decline in eastern Africa’s large carnivore species should have started well before 1.5 million years ago becauseH. erectus had emerged by nearly 1.9 million years ago. Species numbers are a blunt instrument at best for tracking the progress of an entire order of mammals over time because a reduction in numbers of one of its group can be masked by an increase in another. If two sabertooth species go extinct but are replaced by lions and leopards, the numbers will remain the same, but the community will have undergone a major change because lions and leopards can take a broader range of prey than sabertooths could,” says Werdelin.

Werdelin reasoned that a better way to measure carnivore diversity is not just to look at the number of species, but on how diverse their roles in the ecosystem are as well. The cats, for example, are highly adapted to eating meat and thus qualify as hypercarnivores. But other carnivores are omnivorous—dogs, for example, will eat a wide variety of food in addition to meat. Still others, such as raccoons, are hypocarnivores, eating very little meat and subsisting mainly on fruits and vegetables.

Carnivore species in Africa today – a mere fraction compared to ancient times

To visualize the  diversity of form  Werdelin and colleagues performed  a statistical analysis, thereby creating a two-dimensional plot that  he calls the morphospace. This morphospace represents the diversity of form (and inferred function) that exists within a group of related organisms, in this case the carnivores that lived in Africa over the past 3.5 million years. Plotting separate morphospaces for carnivores from distinct time intervals and comparing them offers a sense of how carnivore anatomy and eating habits shifted over time.

As reported in a paper published in the journal PLOS ONE, it appears the large carnivore families that occupy eastern Africa today represent only a fraction of the morphospace of the carnivores in the 3.5-million- to three-million-year interval, when species diversity was at its highest. According to Werdelin, these carnivores  lost nearly 99 percent of its so-called functional richness, which is to say today’s carnivores fill far fewer kinds of ecological roles than their predecessors did.  This dramatic decrease began  in the interval between two million and 1.5 million years ago, which means that the process must have started before that time—bringing the onset of this major decline in line with the origin of H. erectus.

Some researchers contest this idea, however, reasoning that H. erectus was neither numerous enough to cause these changes, nor hungry enough for meat (controversial findings).

“Like any nascent hypothesis, this one comes with a series of problems that need resolution. The most significant of these issues concerns the timing of the events described here, both in terms of when the carnivores began going downhill and when humans started to pose a competitive threat to them. We need a clearer picture of what happened and when to draw firm conclusions about cause and effect. In addition, scientists do not know whether hominins were sufficiently numerous and competitive to cause such massive change to the carnivore community,” says Werdelin.

Werdelin believes collecting more fossils from the   2.5-million- to two-million-year time interval or more refined techniques for analyzing the fossils  already found today might help better pinpoint when carnivores started to decline in eastern Africa.

“I hope that researchers skeptical of my hypothesis will come up with some ingenious ways of testing it. To that end, another aspect of this idea bears mention. Attempts to explain ecosystem change typically provide a bottom-up perspective, looking at how climate factors affect plants and how changes in those organisms affect the rest of the food chain up to the top predators. My hypothesis about eastern Africa’s large carnivores provides a top-down view, considering how change in the top predators could affect the primary producers at the bottom of the food chain, such as grasses and trees,” Werdelin says.