Beaver and Wolves

I heard a Ranger in Yellowstone last month claim that one of the benefits of wolves in the Yellowstone Ecosystem was a resurgence of beaver. He claimed 100 beaver...but was misinformed in at least two ways. I reported in an earlier post how giving wolf killing of Elk credit for increasing beaver food was simply a lie.

I found this today in a YNP WEB posting: "To help restore the population of beavers on Gallatin National Forest, 129 beavers were released into drainages north of the park from 1986 to 1999. Park-wide aerial surveys began in 1996 with a count of 49 colonies and increased to 127 by 2007; dropping to 118 in 2009 and 112 in 2011."

The Ranger neglected to note that the beaver increase was due to planting. Young beaver travel upstream to create new colonies. Yellowstone is upstream from the planting locations. His other mistake was his number should have been colonies. And at least in this data the numbers are decreasing since the planting.

The more likely cause->effect chain is that beaver swam upstream and built new dams.  In other words Yellowstone beaver were planted. The new dams from the planted beaver encouraged more willow growth. I witnessed that last month as my Elk hunting campsite. There were several new beaver dams and the willows were going crazy. Since the Elk never hung out in that area on the road I'm sure the wolves that killed the Elk on the surrounding mountains had no impact on that.

I suspect the relationship of Grizzly Bear to beaver is more profound. I have seen beaver houses dug up by Grizzly in the Bechler area. I don't think wolves do that. They are too busy killing Elk.

 

Here is a surprisingly realistic view on this topic by a pro-wolfer:  Wolf Blog  The article notes,

"Mech’s primary point–that correlative evidence is insufficient for establishing causation–is important, and I hope it does not get lost here."

 

Just to be clear: I don't argue that the wolves have not had an effect in Yellowstone or elsewhere. Clearly they have devastated the Elk herd in Yellowstone and other locations. Crashing the Elk population by 80% is certainly going to allow more growth of their winter browse. I have also recently seen more deer and antelope in Yellowstone than in the previous 40 years. This is only an anecdotal personal observation but it caused me to wonder what that might be about. I recently found a suggestion as to causality that might be worth investigating. The suggestion is that the wolves have killed off many of the Coyote, and the Coyote used to preferentially eat the antelope and deer fawns. It also suggested wolves don't bother with the small fawns of deer and antelope. That's something worth following up on.