Yellowstone Reports

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Spring carcasses attract the carnivores

…and the viewers
by Dr. Nathan Varley

June 1, 2010

Mist rose from the surface of the forested lake on the rain-soaked morning of our arrival.  We searched the north shore and found no trace or clue to the outcome of the drama unfolding here the night before.  The previous evening a cow elk, injured by a wolf, was standing up to her withers in the lake.  The wolf waited on the far shore, perfectly patient in anticipation of its next encounter with the elk.


Around the next corner we glimpsed the south shore of the lake and there wading into the shallows of the mist-shrouded lake was the wolf.  It tugged and tore at the flesh swallowing large stringy chunks in a single gulp.  A hush hung over the gathering thrilled observers who hid in the nearby trees with only the sounds of fluttering camera shutters audible.  We had our outcome, and it was deemed merciful--the misery of the elk, so weakened by injury and noticeably shivering from hypothermia the night before, had at last ended.  The wolf, a large gray male marked as number 587 had worked and waited nearly a day for this meal.  He ate for awhile and then in a moment of purpose, grabbed what looked to be a lobe of the liver and trotted off, probably to a den of pups.


Across Yellowstone on a collection of grassland ponds, a grizzly bear had waded into deep mud and murky waters to pull the remains of a bison to the shore.  In a spring ritual as consistent as the birds returning to nest at these ponds, grizzly bears emerge from hibernation and plumb the shoreline depths of these ponds for unfortunate bison who have met their end the previous winter.   Ice and mud form the impenetrable obstacle to bison who wander this way, and attempts to cross can end in a state of inescapable mire.  They die there, frozen in place, and while winter carnivores like coyotes, ravens, eagles, and wolves skim the available surface of these carcasses, the majority is locked below the ice, stuck in the mud, until some greater carnivore can free them.  Enter the bears.  Multiple bears converge, including sows with cubs and mighty boars, as well as, the aforementioned carnivores resuming where they left off months before, but now contending with the bears for access to the spoils.


Park visitors delight at this spring convergence of carnivores.  Indeed, some of the best wildlife viewing often involves these rich sources of protein and fat, and the competition among many species to get it.  The group I was hosting for spring wildlife viewing, members of a mixture of outstanding conservations groups, Keystone Conservation and the California Wildlife Center, were treated to their best glimpses of a wolf at the forested lake, and better yet, an ending to the story started the evening before and beheld on their final morning in the park.  I can only hope for, or dare to anticipate, similar viewing as a result of carcasses in the spring weeks to come as I embark with new intrepid wildlife seekers on our upcoming Spring Wolf and Bear Adventures.


Later in the day, park rangers removed the remains of the carcass from the edge of the forested lake.  While unpopular with visitors this is necessary to prevent accidents involved with visitors

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View slide show

Wolf 587 stands near its kill at the edge of the lake

Wolf 587 feeds

Wolf 587 departs from the carcass

Grizzly bear consumes a leg from a bison carcass

Coyote pauses to look around while scavenging on the remains of a carcass.