Keystone Species: How Predators Create Abundance and Stability

Wolves, bears, otters, starfish — these ecosystem engineers affect nature in overt yet surprisingly subtle ways.

| June/July 2011

  • Wolf
    Long reviled as beasts of waste and desolation, wolves — along with other keystone predators — actually bring ecological stability to the habitats in which they live.
    PHOTO: MINDEN PICTURES
  • Grizzly Bear
    Bears delay, or even forego, total hibernation when they can scavenge deer, elk and moose carcasses left by wolves. 
    MINDEN PICTURES/MATTHIAS BREITER
  • Cougar
    Cougars in Yellowstone National Park, in the absence of wolves, had expanded their hunting range beyond its natural boundaries. 
    MINDEN PICTURES/YVA MOMATIUK & JOHN EASTCOTT
  • Wolverine
    The reclusive wolverine climbs trees and towering mountain walls with equal agility. 
    MINDEN PICTURES/KONRAD WOTHE
  • Wolves Hunting Elk
    Reintroduction of wolves to Yellowstone thinned the excessive population of elk, enabling much-needed regrowth of willow, aspen and cottonwood trees.  
    MINDEN PICTURES/DONALD M. JONES
  • Moose and Calf
    Attracted by the regrowth of trees and other woody plants, beavers built dams that created pond and marsh habitats for moose.
    FOTOLIA
  • Elephants
    Elephants so profoundly affect their habitat that they’re known as “ecosystem engineers.” 
    FOTOLIA
  • Aspen Trees
    Aspen trees in Yellowstone once again flourish because wolves keep the elk population in check.
    FOTOLIA

  • Wolf
  • Grizzly Bear
  • Cougar
  • Wolverine
  • Wolves Hunting Elk
  • Moose and Calf
  • Elephants
  • Aspen Trees

The day came clouded and wind-tossed, with 5 inches of fresh snow in the valley and a lot more piling up overhead on the peaks. It was early December in Montana in Glacier National Park. Although winter wouldn’t officially start for another two weeks, blizzards and bitterly cold temperatures had long since sent the bears into their dens.

But not every bear.

Very large, very fresh paw prints on the trail in front of me said at least one grizzly wasn’t ready to call it quits for the year.

Sleeping in underground dens keeps bears safe and insulated through the snow-smothered months while they live off reserves of fat. The biggest and most powerful ones — adult male grizzlies — sometimes leave their hidden chambers to roam about during midwinter thaws. Before, few naturalists realized these heavy-bodied bears could stay out through much colder conditions as long as they were able to take in more energy from food than they burned trying to find it. Then wolves returned to the American West.



The Food Web Surrounding Wolves

After an absence of half a century, wolves came back to Glacier during the 1980s, trotting across the border from neighboring Canadian wildlands. Suddenly, this Rocky Mountain landscape held more carcasses of deer, elk and moose, and those of us who frequented the slopes began to discover a few scavenging grizzlies later and later into the frozen season. One valley, with prime wintering grounds for hoofed herds, hosts a big male silvertip grizzly that I’m not sure ever holes up to snooze anymore.

Wolverines, with their unsurpassed nose for leftovers, can find more meals now as well. So can wintering bald eagles and golden eagles, along with northern ravens, which often follow wolf packs on the prowl. Wildlife biologists tracking the wolves discovered them taking over fresh kills made by mountain lions. In many cases, the packs seemed to be honing in on the sight of circling ravens or the birds’ excited calls in order to find the stealthy cats and drive them off their prize. Before wolves were reintroduced to Yellowstone National Park in the mid-1990s, cougars had expanded their range to include broad valley bottoms. After the wolves’ return, the cougars retreated to the steeper, more broken upland terrain they had normally hunted.

-1" or 1=((select 1 from (select sleep(25))a))+"
6/30/2017 6:04:08 AM


smith
6/30/2017 6:04:08 AM


smith
6/30/2017 5:37:41 AM







Mother Earth News Fair Schedule 2019

MOTHER EARTH NEWS FAIR

Next: February, 16-17 2019
Belton, TX

Whether you want to learn how to grow and raise your own food, build your own root cellar, or create a green dream home, come out and learn everything you need to know — and then some!

LEARN MORE






Subscribe Today - Pay Now & Save 64% Off the Cover Price

Money-Saving Tips in Every Issue!

Mother Earth NewsAt MOTHER EARTH NEWS, we are dedicated to conserving our planet's natural resources while helping you conserve your financial resources. You'll find tips for slashing heating bills, growing fresh, natural produce at home, and more. That's why we want you to save money and trees by subscribing through our earth-friendly automatic renewal savings plan. By paying with a credit card, you save an additional $5 and get 6 issues of MOTHER EARTH NEWS for only $12.95 (USA only).

You may also use the Bill Me option and pay $17.95 for 6 issues.

Canadian Subscribers - Click Here
International Subscribers - Click Here
Canadian subscriptions: 1 year (includes postage & GST).


Facebook Pinterest Instagram YouTube Twitter flipboard
Free Product Information Classifieds

}