cA tri-fecta of articles and commentary I have brought to your attention over the past three days regarding our giant Mega-Fauna that ruled the Americas and then blinked out some 8-12,000 years ago...............Today, our good friend and consistent contributor to this Blog, Ecologist George Wuerthner, providing further insights regarding the "triple-play" of climate change/vegetation growth(patchiness of that growth) and the resulting food supply quandry that our Giant Grazing animals had to make do with............This new herbivory habitat condition then making it easier for archaic humans and other mega carnivores to successfully hunt these the Grazers and send them on a spiraling down and out path to extinction ............With those Grazers going "bye bye" rapidly,the predator suite that relied on those grazers also found themselves "going-going-gone" due to smaller and smaller prey animals remaining on the land............. These smaller Grazers were not sufficient enough in caloric content to supply sustenance to those Mega Carnivores.............There is a plus and a minus when you are LARGE BODIED------Big translates to being strong, fast and able to dispatch your prey efficiently and to be able to defend yourself successfully,,,,,,,,,,,The negative side of this equation(large bodied) is that you have to consume enough foodstuffs to maintain that mass.................Climate/foodstuffs/humans---perhaps disease from domestic canines and humans themselves,---The perfect storm of destruction--All adding up to bringing an end of a fantastic era of animal life around the world--THE MEGA=FAUNA

From: George Wuerthner ;gwuerthner@gmail.com;
Date: April 19, 2016 at 10:33:27 AM PDT
To: "Wolves, Wolf Facts, Cougars, Cougar Facts, Coyotes, Coyote Facts - Wolves, Cougars, Coyotes Forever" <rick.meril@gmail.com;
Subject: Re: Coyotes,Wolves,Cougars..forever!

Rick

I studied this question for a major senior thesis in college. I have not seen anyone who has taken exactly the same approach that I did in my paper. Basically what I hypothesized at the time was looking at how climate change at the end of the Ice Age shifted vegetation and created a more heterogeneous patchwork of plant communities. 

some of the Mega Fauna of the Americas

Larger mammals, in particular, like wooly mammoths, etc. need to consume huge amounts of food daily. Due to the changing shifts in vegetation, not only did the nutritional quality of the vegetation change (nutrition declines as climate warms), but the amount available shifted into smaller units. That meant large mammals like the mammoth had to wander further to get enough to eat. It also meant that they might be more vulnerable to predation (whether from humans or other animals) since their occurrence would be more predictable and localized.

Giant Beaver and Mammoths

 Finally due to the very slow reproductive rate of these larger mammals, their ability to compensate for losses is poor. Add in the stress caused by climate shifts, vegetation changes, and perhaps a new predator (humans) and you get a decline in these larger animals. Remember one of the main lines of defense of the larger Ice Age animals was their size, but size has a cost. 


Cave Bear and Giant Bison

We see this same shift in bison. The Ice Age bison was much larger than the plains bison that survived. But it required more food to maintain that large size. With plant community changes, it became more advantageous to be smaller and have a reduction in food requirements. 


The American Lion

We also saw this in wooly mammoths. There was a very small subspecies that was found on the Channel Islands (I believe) that was adapted to the limited food resources on an island. 

Best, 

George

Saber Tooth Tiger and Dire Wolves