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Why are lions not as big as elephants?
January 16, 2007Carnivores are some of the widest ranging terrestrial mammals for their size, and this affects their energy intake and needs. This difference is also played out in the different hunting strategies of small and large carnivores. Smaller species less than 15-20 kg in weight specialize on very small vertebrates and invertebrates, which weigh a small fraction of their own weight, whereas larger species (>15-20 kg) specialize on large vertebrate prey near their own mass. While carnivores around the size of a lynx or larger can obtain higher net energy intake by switching to relatively large prey, the difficulty of catching and subduing these animals means that a large-prey specialist would expend twice as much energy as a small-prey specialist of equivalent body size. In a new article published by PLoS Biology, Dr. Chris Carbone and colleagues from the Institute of Zoology, Zoolog ical Society of London reveal how this relationship might have led to the extinction of large carnivores in the past and why our largest modern mammalian carnivores are so threatened.
The authors provide a model of carnivore energetics in relation to predator and prey size, and compare the model predictions with observed estimates of metabolic rates and intake rates taken from animals in the wild. By analyzing the balance between energy intake and expenditure across a range of species, the authors reveal that mammalian carnivores would not be able to exceed a body mass of one ton. Their model predictions are consistent with the data we have. Most mammalian carnivores are relatively small compared with the largest extinct terrestrial herbivorous mammals, such as the Indricothere, which weighed around 15 tons. The largest existing carnivore, the polar bear, is only around half a ton, while the largest known extinct carnivores, such as the short-faced bear, weighed around one ton. The authors also note that the largest terrestrial non-mammalian predators, such as Giganotosaurus and Tyrannosaurs, may have achieved their massive size by having a lower metabolic rate. Indeed, previous estimates of total metabolic rate for these species are similar to those of a mammal weighing about a ton.
We know that the largest carnivores that exist today are particularly vulnerable to threats imposed by humans and have been shown to have higher rates of extinction in the fossil record than smaller species even prior to the evolution of man. Carnivores at the upper limits of body mass would have been heavily reliant on abundant large prey to both minimize energy expenditure and maintain high rates of energy intake. Slight environmental perturbations, anthropogenic or otherwise, leading to lower prey availability, could readily upset this energy balance. It may have also contributed to the extinction of the largest carnivores and explain why the largest modern mammalian carnivores are so rare and vulnerable today.
Public Library of Science
Public Library of Science
Carnivore Current Events and Carnivore News RSSPhotos reveal Myanmar's large and small predators
Using remote camera traps to lift the veil on Myanmar's dense northern wild lands, researchers from the Wildlife Conservation Society have painstakingly gathered a bank of valuable data on the country's populations of tigers and other smaller, lesser known carnivores. These findings will help in the formulation of conservation strategies for the country's wildlife.
Great white's mighty bite revealed
Using sophisticated computer modelling techniques they have also calculated that the bite force of the great white's extinct relative, the gigantic fossil species Carcharodon megalodon (also known as Big Tooth) is the highest of all time, making it arguably the most formidable carnivore ever to have existed.
Outdoor enthusiasts scaring off native carnivores in parks
Even a quiet stroll in the park can dramatically change natural ecosystems, according to a new study by conservation biologists from the University of California, Berkeley. These findings could have important implications for land management policies.
Scientists believe photograph depicts wolverine in California
U.S. Forest Service scientists believe an Oregon State University graduate student working on a cooperative project with the agency's Pacific Southwest Research station on the Tahoe National Forest has photographed a wolverine, an animal whose presence has not been confirmed in California since the 1920s.
Captive carnivores not up to wild living
A study by the University of Exeter has highlighted the problems of reintroducing animals to the wild for conservation projects. Published online in the journal Biological Conservation, the research highlights the low survival rates of captive carnivores that are released into their natural habitats.
Scientists map out potential for restoring California fisher populations
U.S. Forest Service and U.C. Santa Barbara scientists believe they have identified the habitat needs for Pacific fishers, a rare California mammal that is a candidate for reintroduction efforts and listing under the Endangered Species Act.
Insect attack may have finished off dinosaurs
Asteroid impacts or massive volcanic flows might have occurred around the time dinosaurs became extinct, but a new book argues that the mightiest creatures the world has ever known may have been brought down by a tiny, much less dramatic force - biting, disease-carrying insects.
Choosing dry or wet food for cats makes little difference
Although society is accustomed to seeing Garfield-sized cats, obese, middle-aged cats can have a variety of problems including diabetes mellitus, which can be fatal.
Toothy dinosaur newest to come out of southern Utah
The newest dinosaur species to emerge from Grand Staircase-Escalante National Monument had some serious bite, according to researchers from the Utah Museum of Natural History at the University of Utah.
T. rex quicker than Becks, say scientists
T. rex may have struggled to chase down speeding vehicles as the movie Jurassic Park would have us believe but the world's most fearsome carnivore was certainly no slouch, research out today suggests.
More Carnivore Current Events and Carnivore News Articles
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| The Tender Carnivore and the Sacred Game. Drawings by Fons Van Woerkom. by Paul. SHEPARD | |
| Journeys Of The Catechist: Carnivores Of Light And Darkness; Into The Thinking Kingdoms; A Triumph Of Souls by Alan Dean Foster | |
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 | Coexisting with Large Carnivores: Lessons From Greater Yellowstone As in the rest of the United States, grizzly bears, wolves, and mountain lions in and around Yellowstone National Park were eliminated or reduced decades ago to very low numbers. In recent years, however, populations have begun to recover, leading to encounters between animals and people and, more significantly, to conflicts among people about what to do with these often controversial... |
 | Circus Carnivore by Mark Svendsen When Kate doesn't get her way she likes to pout, kick, scream, andshout. She loves to be roodle (she's no goodle-two-shoodles). Andshe's got lots of help there, because inside her head is the Noise-amatron,the nonsense machine that makes all of her wailing andother naughty noises. And there are lots of Noise-a-matron workers—Noolman, Tubswort & Co.—who make sure her misbehaviormachine is... |
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