Biology Reference
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San Diego Killer Whale
Hence, the declining elk populations around Yellowstone have put pressure on local
communities. The greater Yellowstone elk population has been reduced by 75% by wolves. A
friend of mine in Sweden has not been able to get a moose on his farmland because of a wolf
den but last year somebody killed one of the wolves and the den disappeared. The moose have
once again returned. Of note, it was uncommon for us to see elk in our visit to Yellowstone
earlier this year. In the early 1900s when elk were overpopulating Yellowstone, a railway
magnate supposedly paid $1 each for some 1500 that he put on his railway carts and shipped
down to his ranch at Vermejo, now owned by Ted Turner. This restorancy allowed the spread
of elk over New Mexico. On the other hand some 40,000 visitors can now see wild wolves in
Yellowstone. It has been argued that less elk have also allowed beavers to again thrive on
willows and aspen because elk are not destroying them, and build dams and create again
habitats for moose and birds; such are the enigmas. This theory has been criticized by wolf-elk
interaction researcher Middleton who has studied them in the Greater Yellowstone Park. Part
of the controversy revolves around the issue of so called “top down trophic cascade” species
decline. Some believe this trophic cascade will result in the 6 mass extinction that we may be
entering. Some 10 to 15 thousand years ago woolly mammoth and sabre tooth's (Smilodon
fatalis) went extinct perhaps because humans tipped the balance of the ecosystem by competing
with sabre tooth. The sabre tooth and mammoth were removed as top predator, allowing
changes in lower populations. It is likely that man and mammoths and sabre tooth's lived in
balance until some tool advance or hunting process advance tipped the balance in favor of
humans. In a similar way, humans have kept the elephant population in control for thousands of
years by killing them for food until European hunters showed up with rifles and then decimated
the population. For Northern Eurasian and American continents some 10,000 years ago, once
the competing grazers were eliminated, bison flourished. At that time lions, horses, mastodons,
giant ground sloth, different types of bison, camels, wolves, two types of sabre tooth's were
present. The same occurred in Africa. When there is loss of apex predators there is an increase
of smaller predators (mesopredators), like coyotes in the USA, that in turn kill animals like
foxes and allows overgrowth of animals like mice. Hence also the introduction of wolves
changed the balance back. Elk declined, aspen increased, beaver increased, and moose
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