Wolves Trigger Trophic Cascade

Some time ago I wrote a post called “When In Drought Find a Beaver” –


The story of Yellowstone Park reintroducing wolves takes the concept to a whole new level. Trophic cascade is the term given to trickle down effects on eco-systems when you crown a previously absent predator top dog – in this case literally when in 1995 Yellowstone Park released wolves, a species absent for 70 years.

Those years saw an explosion in deer population – decades of  growth went unchecked as the voracious nibblers cleared vegetation, ate saplings, grass, flowers, and berries. Valleys and river banks eroded, mud and debris washed away from barren hillsides, inundating streams and rivers – directly impacting fish, amphibians and reptiles.

Enter Mr. Wolf – not only did deer population drop, their behaviour took an abrupt turn. Deer avoided valleys where they could easily be trapped, they fled to the hills allowing vegetation’s return along river banks and low lying meadows. Barren slopes suddenly grew aspen, birch and willow trees. As saplings became young forests – birds returned, beavers moved back – with abundant wood, they built dams. Newly formed pools and slower moving water gave habitat to fish, muskrats and frogs. Wolves killed coyotes, mouse and rabbit numbers grew bringing back weasels, hawk, and eagles. Plentiful berries saw bear numbers rise.

In less than twenty years wolves redefined an eco system, more incredibly –  managed to complete transform geography. Anyone not gob smacked by one seemingly innocent “tweak” ought to think again. Anyone not pondering consequences of our slash and burn mentality – those unable to make the obvious connection between this tale and environmental issues such as the tar sands – might want to reconsider apathy as a fall back position.

Every one of our actions comes with a definable reaction in the natural world. It works both ways – for and against us, but never without consequence. Remember that the next time you roll your eyes, change channels, turn the page or click away from environmental issues. Take a few minutes to watch this video – I’d be hard pressed to come up with a better example of environmental domino effects – a cautionary tale illustrating tired old “balance of nature” to perfection. We all need to smarten up.


17 thoughts on “Wolves Trigger Trophic Cascade

  1. Fascinating! And in such a short spell of time. The city I’m living in is taking part in a wildflower experiment, with strips planted all over the city. It’s great to see bees everywhere again. But this makes me wonder what other changes will happen as a result.

    • We had a lovely old tree stump in our back yard. I made a flower bed around it – my daughter convinced for years it was home to the queen of the fairies. Without my knowledge, the gardener thought he was doing a favor when he yanked it out.We were heart broken. Within a few weeks, woodpeckers, blue jays and song birds who had graced the yard for ages disappeared. The decaying wood had been their supermarket for grubs and insects.
      Something we had taken for granted until they were gone.

      Off the top of my head – watch for more butterflies in areas where wildflowers thrive. With that comes caterpillars and increased bird populations.Natural cause and effect always follow introduction or elimination of any species or plant. 🙂

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