by Wayne Lusvardi
Re: Chip Ward, “Building With Wolves,” (Sept.28).
Chip Ward, a self-described former anti-pollution organizer, activist and writer, claims in the Sept. 28 Los Angeles Times (“Building With Wolves”) that when wolves were exterminated in Yellowstone National Park in the early 1900’s the result was a dewatering of the land. Conversely, Ward says wolf reintroduction has created more natural water reservoirs from beaver dams in Yellowstone.
Ward’s contention that increasing water ponding in Yellowstone Park is related to wolf reintroduction apparently comes from a 2008 study in the journal Ecological Applications by Danielle Bilyeu, David Cooper and N.T. Hobbs - http://www.esajournals.org/doi/abs/10.1890/07-0212.1
Ward states that reintroducing wolves resulted in fewer elk able to forage on willow and aspen tree seedlings. Beavers thus have more food and building materials to impound water behind beaver dams. The number of beaver dams in Yellowstone went from one to twelve in Yellowstone after wolves were reintroduced according to Ward. But this is inconsistent with surveys conducted by Sue Consolo Murphy in 1988-89 that found 71 active beaver lodges in Yellowstone prior to the re-entry of wolves. http://www.montana.edu/ecology/current%20pages/YS16(3)beaver.pdf
The National Park Service reports that 21 wolves comprising 3 wolf packs were reintroduced into Yellowstone in 1995. But the wolf population has declined from 272 (31 packs) in 2002 to 96 (14 packs) in 2009 due to natural causes.
Ward’s assertions are not consistent with recent reputable wildlife studies easily found online. Matthew Kaufman of the USGS in a paper in Science Daily (9/1/2010) “Are Wolves Saving Yellowstone Aspen Trees from Elk?” found that elk are not responsible for the decline of Aspen trees in Yellowstone since 1890. Kaufman and his research team report that no Aspen groves are regenerating in Yellowstone since relocating wolves into the park. (http://www.sciencedaily.com/releases.2010/09/100901111636.htm.
Biologists have also noted a natural “boom and bust” cycle of beaver populations mostly dependent on the availability of Aspen trees as food. Aspen is a sun-loving species that grows after disturbances, such as the 1988 Yellowstone fire.
As long as wolves have a possible over-population of elk and deer in Yellowstone to feed on they will apparently be satisfied. However, when elk, moose, and deer get scarcer, wolves will feed on beaver. As Dietland Muller Schwarze of the Department of Environmental and Forest Biology of the State University of New York states in his definitive book The Beaver: Natural History of a Wetland Engineer: “In Southern Quebec beavers constituted 29% to 44% of the biomass in the diet of wolves from May to November…Experimental wolf reduction in the Province of Quebec suggested an important impact of wolves on beavers: beaver numbers increased when managers reduced wolf numbers, but decreased when the wolf population was allowed to grow again.”
Mr. Ward is the apparent selected mouthpiece by those whose livelihoods may depend on an expensive high profile ecological experiment in reintroducing wolves into national parks, and the imposition of wolf packs on private cattle ranches without just compensation for livestock losses, that now requires visible justification to the public for possible refunding and renewal of the endangered designation for wolves under the Endangered Species Act. More water ponds with cute, fuzzy beaver is the perfect rationale and photo op.
The resurgence in beaver dams may have resulted from a rebound of Aspen and Willow tree growth from the 1988 Yellowstone fire, the resistance of drought-tolerant willow trees, warmer and drier winters, natural boom and bust population cycles, or other unknown factors. Where is the control group from a study of a forest with absent wolves and absent water ponds and controlling for natural ebbs and flows of Aspen and Willow tree stands? Without that Ward’s claims are eco-quackery.
In conclusion, if we add into Mr. Ward's explanation of how the natural food chain works the missing fact that wolves eat beavers, we get the following circular reasoned syllogism:
If wolves feed on elk,
and elk and beavers feed on trees,
and beavers build dams out of trees,
but wolves eat beavers,
then wolves must be forever damned?.