How important are wild predators to our well-being?

Jan 2018
1,609
China (Hong Kong SAR)
#2
That's interesting.

"Our paper identifies studies that have shown these benefits across a broad spectrum. These include US mountain lions reducing deer-vehicle collisions, bats saving corn farmers billions of dollars each year by reducing crop pests, and vultures saving millions in livestock carcass removal."

The part concerning natural predators as a means to pest control is quite well known, so this is a part of the scientific method in its repetition by peers.

"We review these benefits, highlighting the most recent studies that have documented their positive effects across a range of environments."

https://www.nature.com/articles/s41559-017-0421-2
 

Corvidius

Ad Honorem
Jul 2017
2,550
Crows nest
#3
Remove the predators and the herbivore population will suffer. They could strip areas clear of vegetation, and even if they moved on, would leave behind a wasteland for other wildlife less mobile. Then they can find they have nowhere with enough food to move to as all the herbivores are stripping all the vegetation everywhere. The health of the population as a whole will suffer as the sick, the lame and the old will not be culled. Crows and ravens, not normally seen as predators, were decimated in the corn belt as it was thought they were decimating the corn crop. The reality was that they did far more good than harm by controlling the insect population that destroyed far more crops than the birds. Result, enjoy your meal of chemicals....
 
Mar 2017
862
Colorado
#4
Remove the predators and the herbivore population will suffer. They could strip areas clear of vegetation, and even if they moved on, would leave behind a wasteland for other wildlife less mobile. Then they can find they have nowhere with enough food to move to as all the herbivores are stripping all the vegetation everywhere. The health of the population as a whole will suffer as the sick, the lame and the old will not be culled. Crows and ravens, not normally seen as predators, were decimated in the corn belt as it was thought they were decimating the corn crop. The reality was that they did far more good than harm by controlling the insect population that destroyed far more crops than the birds. Result, enjoy your meal of chemicals....
This was observed in Yellowstone a couple of decades before the fires.

There was no hunting in Yellowstone, and all the predators had been eliminated. The elk population exploded, over grazed the vegetation, and got sick. Antlers were gnarled/deformed, many animals had mange, many animals were too underfed to make it through the Winter, and the elk had little resistance to the brucellosis endemic to the bison. I walked through a Winter kill area and counted over 20 carcasses in one little valley.

They made the correct wildlife management decision, and "thinned the herd". There was a public outcry over this from well meaning under informed wildlife groups, and local shopkeepers, who saw a drop in purchases of souvenirs like rubber elk. From that instance, the Nat'l Park Service's hands were tied in terms of "thinning" as a management tool ... and still are, as far as I know.

The result was that the elk herd bounced back fantastically. Less elk, more vegetation for each one, resulted in iconic trophy animals .. and the population began growing ... again.

Then they introduced wolves. Last I checked, I believe the elk numbers have stabilized.

There are multiple studies that have shown that predator and prey evolve together. Typically, a healthy predator can not prey on a healthy adult. Wolves carefully scan herds for the weakest individuals, so they limit their own risk. The wolves primarily take the old, sick, & young. The herds are MUCH healthier with active predators. As a side issue, all predators will scavenge (if it's not too rotten) and serve as a cleanup squad to avoid spread of viral/bacteria disease from rotting carcasses. The master cleaners, vultures, actually poop antibiotics onto their feet.

Even picking out the young, predators can't take them ALL. They take the ones with defects, and ones that aren't protected appropriately or whose mom's have a problem defending them.

Even lions do this. Without any kind of sentient reasoning, a predator knows that a broken bone means death. They don't take any risks they don't have to. I live in an area that supports three mountain lions. We can only live here because they don't know what people are and don't want to risk attacking something that might hurt them. I walk four miles a day with my dogs, but follow the lion-rules. Of course, once a lion attacks a human, they *HAVE* to hunt it down.

Here's a nice little website, showing that most predators have a failure rate of 60-70% ... largely because they give up when things go sideways:
http://www.discoverwildlife.com/animals/hunting-success-rates-how-predators-compare



An elk's been hanging around my backyard. Yeah, he's got an impressive rack, but he's got an enormous chest ... bigger than a whiskey barrel. MAYBE two men could join their arms around him. He's an amazing monumental thing. Some day he'll be lion food, but not any time soon. Those antlers aren't just for show.
 
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Jake10

Ad Honoris
Oct 2010
11,960
Canada
#6
I suppose this was in the back of my mind, but as a farmer, there is an association with a predator and a danger to my animals. Farm animals are easy prey, but somehow farmers will need to take the importance of wild predators into consideration.
 
Mar 2017
862
Colorado
#7
I suppose this was in the back of my mind, but as a farmer, there is an association with a predator and a danger to my animals. Farm animals are easy prey, but somehow farmers will need to take the importance of wild predators into consideration.
This is absolutely a legitimate concern. Montana farmers *HAVE* to kill grizzlies and wolves to protect their livestock when they get lazy from earning a living and wander in from the park. Any defense against predators has been bred out them. Similar stuff happens around the fringes of every nature preserve in the world.

This is why there has to be "wildlife management" in the first place. "Why can't we leave the animals alone to be regulated by nature?"

Because *WE* live here. If everybody (including Native Americans) moved out of North America & took all the fences down? The wildlife would be able to settle into natural cycles. I don't believe that's an option.


Of course the symbiotic relationships between some animals and crops are more complicated. Some birds seem to damage a percentage of crops, but it turns out the yield is actually greater than if they're allowed to prey on the bugs. If I could remember the exact species, I'd mention them. Sorry.
 
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Apr 2017
676
Lemuria
#9
The prey always mirrors its predator. Without a predator, the prey (as a population over time) undergoes a sort of biological deterioration. Similarly, the predator must constantly evolve to catch up with its prey. In other words, the predator weeds out of the sick (stops species specific diseases from spreading) and the weak and drives each other evolution. It keeps of herd healthy and in peak condition. Both become faster, stronger, stealthier, deadlier etc. One great example is shark vs tuna.
 
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