In a previous post, Whites Are The Original Immigrants I mentioned Yellowstone National Park and the reintroduction of wolves. In response to the story, I received the following comment:
They are finding once again the wolves are overpopulated and causing problems. What have you found out lately about the wolves? Interested because I lived in Montana. What do you see with the Eagles and the Grizzly Bears population?
Yellowstone has fewer elk, which means more willow and aspen.
But the big question is, were the wolves responsible for the transformation of Yellowstone's ecosystem? Yes or No? Or maybe. A little bit?
"The hypothesis that wolves are ecosystem engineers that have suppressed elk herbivory and triggered large scale recoveries of aspen and willow in northern Yellowstone assumes that wolves were the principal cause of the elk decline." Aaron Bott
What is a trophic cascade?
Think of a waterfall. At the top of the waterfall is a predator. Reintroducing the wolves to Yellowstone had direct or indirect effects on the biodiversity throughout the park. However, it's not enough to consider only the wolves, when other predators like bears and beavers, weather, humans, disease, fire, etc. must also be factored into the landscape
It's not a simple equation of river + wolves = ecosystem.
What about the elk?
When Yellowstone opened in 1872, it was the world's first national park. I didn't know that, did you? It didn't have a park service, so the army managed it. Another fact you might not know; hunting was allowed for the first few decades! Then when hunting was banned, poachers moved in for the kill. Market hunters dominated the era, which earned the nickname the great slaughter of the 1800s.
In the park and across America, hunters decimated bison herds from 30 million to 325 in 1884. Today, Yellowstone has 5,000, and America in total has 500,000.
Killed for profit, the elk and other hooved populations fell so low the park service decided to exterminate all the wolves and cougars in 1926. Thanks to strict regulations and penalties, the elk population thrived.
By 1940, the elk had eaten so much of the park's plants and trees that biologist, Olaus Muire, recommended a two-thirds reduction in the herd.
Up until 1968, the park service killed or removed for use elsewhere 70,000 elk from northern Yellowstone. Park management differed significantly then. They didn't understand the ecology of predators on the land, so they got aggressive.
In 1969, scientists disagreed with the way the park had become a national amusement. So, with park management, they introduced a natural regulation process to stop the general public from feeding the animals junk food and trampling precious wild plants. They thought the lack of food would be enough to keep the elk population down. They didn't consider how predators would keep the population down naturally.
Well, that didn't happen. Instead, by the end of the 1990s, 12,000 elk had grown to 20,000 elk in the northern part of Yellowstone alone!
What were so many elk eating?
The elk grazed on cereal in the summer and boxwood shrubs in the winter. Eating grass encouraged growth, but feeding on the delicious green sprouting tips of aspens, cottonwoods and willows stunted their growth. By the late 1990s, stands of Aspens disappeared, older trees died. With no new saplings, the dead trees went unreplaced.
The knock-on effect of overgrazing and lost trees meant the stream banks eroded. The loss of trees made life difficult for beavers. So difficult they died out, and Yellowstone dried up.
The park set loose 31 wolves shipped from Canada in 1998. Since then, an average of 100 wolves has roamed the landscape every year.
Ten years later, the northern range elk population had dropped by 80%.
Can 100 wolves eat 16,000 elk that quickly?
In short, no. Wolves lack the size, claws, bear hug ability, and skull shape to hunt elk so well. They weigh 100 lbs. Elk weighs 500-700 lbs. Do you see a wolf bringing down an elk? In all those films you watched over the years featuring wolves, you know they go after the low-hanging fruit, young, old, and injured prey. As opportunistic hunters, wolves go hungry a lot of the time.
For most of the twentieth century, elk have been the most enduring of all the species in the park. Aaron Bott, the presenter of an hour-long video, says the elk management could be considered controversial.
It's more likely ambush predators; apex or super predators, big cats - mountain lions, tigers, grizzly bears that are doing the heavy lifting.
Speaking of which, bears were dying off, and with only 100 of them left they were listed as threatened on the endangered species list in 1975. By the 90s the population had bounced back thanks to successful management and conservation techniques. So as we saw with the elk population, with the right conditions they thrived, the grizzlies did too.
Unfortunately, (for the elk) the number of baby elk caught and eaten grew from 23% to 60% by the 2000s. The secret of the grizzly and black bears' success is their sense of smell. It's the strongest in the whole of North America! They can easily sniff out a calf in the springtime.
Can you guess what happened next?
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